Arabic logic is a philosophical tradition which has lasted from themid-eighth century down to today. For many years, western study ofArabic logic tended to concentrate on the early parts of its history,especially on the Greek antecedents of Arabic logic, and on thewritings of the foundational philosophers, Alfarabi (d. 950),Avicenna (d. 1037) and Averroes (d. 1198). Recently,however, there have been notable excursions beyond these areas oftraditional concentration, and I make a special effort in this entryto mention the contributions of post-twelfth-century logicians to thephilosophical resolution of disputed points.^[1]

Section 1 of this entry gives some historical context for a vastarray of logical works, and section 2 provides a number of texts assamples of the philosophical arguments they contain. The philosophicalassessment of the arguments is a task that is now underway in thesecondary literature, and I refer to some of these assessments in thenotes. My primary interest, however, is in presenting a set of textswhich illustrate the trajectory of arguments carried on through aformative period of the discipline.

My own preferred term for the material I cover is “Arabiclogic.” The term as I use it refers to a tradition of logicrooted in the texts translated from Greek into Arabic in a movementbeginning in the eighth century CE. The tradition gradually settled ona set of technical terms with which to translate and discuss theAristotelian corpus and its associated late antique commentaries; italso came to agree on what were the major problems in the corpus whichdemanded resolution. Focussed at first on these problems, a continuousline of discussions has evolved and carried forward in one form oranother down to today.

Arabic logic can be said to be Islamic in two senses, both—inmy opinion—of limited significance. First, it is as a result ofthe Muslim conquests from the seventh century on that Arabic came tobe the primary language of learning. Beyond determining the languageinto which the founding texts of the movement were translated,however, the religion of the conquerors played no significant role inthe development of the subject. Secondly, the tradition of Arabiclogic after the thirteenth century was to find a place in the madrasaeducation and, as a result, had to jostle with various Islamicdisciplines treating grammar, rhetoric and forensic argument; in theprocess, Arabic logic gave up its claims to deal with dialectical,rhetorical and poetical discourse. But by the time Arabic logic wasestablished in the curriculum of the institutions of learning, most ofthe formal aspects of what was forever after to be called“logic” (mantiq) had already crystallised.

Being conducted in Arabic is—on myunderstanding—neither necessary nor sufficient for a logic to beconsidered Arabic logic. The problematic of Arabic logic has beenadopted and its register of technical terms calqued or translated intoother languages such as Persian, Turkish, Hebrew and Urdu. To take oneof many possible examples, Nasîr al-Dînal-Tûsî'sAsâs al-Iqtibâs, thoughwritten in Persian, was apt for exact rendition in Arabic in thefifteenth century precisely because it was Arabic logic written inanother language. By the same token, other traditions of logic havebeen conducted in Arabic but are not, on my usage, Arabic logic. Themodern logic in the tradition inaugurated by Frege taught in mostmodern Arab universities, often in Arabic, is not Arabic logic. Sotoo, if it is true that eighteenth-century Maronites wrote logicaltreatises in Arabic based solely on the logic they had studied inRome, they were writing Latin logic in Arabic, not Arabic logic.

• 1. Historical Outline
  • 1.1 The Early Translations
  • 1.2 Farabian Aristotelianism
  • 1.3 Avicennan Aristotelianism
  • 1.4 Logic in the Twelfth Century
    • 1.4.1 Ghazâlî and Logic
    • 1.4.2 Averroes and the End of Textual Aristotelianism
    • 1.4.3 The Avicennan Tradition of the Twelfth Century
  • 1.5 The Avicennan Tradition in the Madrasa and Beyond
    • 1.5.1 Râzî and Khûnajî
    • 1.5.2 Tûsî and the Maragha School
    • 1.5.3 Logic and the Madrasa
  • 1.6 The Delineation of Logical Traditions
• 2. Logical Doctrines under Dispute
  • 2.1 The Subject Matter of Logic
    • 2.1.1 Expressions, Meanings and Intelligibles
    • 2.1.2 Secondary Intelligibles
    • 2.1.3 Conceptions and Assents
  • 2.2 The Contents of the Treatise on Logic
    • 2.2.1 Logic as a Formal Science
    • 2.2.2 Assent and the Context Theory
    • 2.2.3 An AlternativeOrganon?
  • 2.3 Modal Propositions and Modal Syllogisms
    • 2.3.1 Avicenna
    • 2.3.2 Post-Avicennan Logicians
• Bibliography
• Academic Tools
• Other Internet Resources
• Related Entries

1. Historical Outline

1.1 The Early Translations

The Syriac Christians adopted a teaching tradition which includeda truncated version of the AlexandrianOrganon(Porphyry'sEisagoge followed bytheCategories,On Interpretation, and the firstseven chapters of thePrior Analytics). This teachingtradition continued without disruption through the Arab conquests andunder the Umayyad Caliphate (661–750). During this period, however, itevoked little if any interest on the part of the Muslimconquerors.

It was the advent of the Abbasid Caliphate (750–1258) thatsignalled the beginnings of an interest in philosophy on the part ofthe ruling elite. This was to usher in a translation movement which inthe first place translated the Syriac decoctions of philosophy intoArabic, but which later turned to the Aristotelian texts themselvesand the commentaries written on them in lateantiquity.^[2] Anexample of an Arabic translation produced before the Aristotelian turnis the translation by Ibn al-Muqaffa‘ (ex. 756) of a logictreatise that probably came to him from the Syriac via the Pahlavi(probably from a late antique introduction to philosophy; see Gutas1993: 44 fn. 68). The treatise gestures towards theEisagoge,then turns to theCategories,On Interpretation, andthe introductory parts of thePrior Analytics on assertoricsyllogisms (Danishpazhuh 1978). As Pines pointed out long ago, thismaterial corresponds to the Old Logic (logica vetus) of theLatin West (Pines 1996). One must bearin mind, however, that there are important differences betweeneighth-century Arabic logic and the Old Logic of the Latin tradition.First, there were Syriac translations of other Aristotelian logicaltexts available throughout this period (e.g., thePosteriorAnalytics; Elamrani-Jamal and Hugonnard-Roche1989), sothere were scholars about who had a good idea of what later texts intheOrganon had to offer. Secondly, soon after Ibnal-Muqaffa‘ had produced his treatise, other scholars weretranslating complete Aristotelian works into Arabic. We know, forexample, that the Caliph al-Mahdî (reg. 775–785) hadcommissioned translations of theTopics andtheSophistical Fallacies (Gutas 1993: 43).

The translation movement continued to pick up momentum through theninth century, and by the 830s a circle of translators were looselycoordinated around Abû Yûsuf Ya‘qûb b.Ishâq al-Kindî (d. c. 870). Kindî produceda short overview of the whole of theOrganon (translated inRescher 1963a), and members of his circle produced: an epitome of andcommentary on theCategories; an epitome ofOnInterpretation; a version of theSophistical Fallacies;and probably an early translation of theRhetoric.^[3]

Somewhat later, perhaps from the 850s, the great Syriac Christiantranslators Hunayn ibn Ishâq (d. 873) and his sonIshâq ibn Hunayn (d. 910) began to produce integraltranslations of complete works from theOrganon, generally byway of Syriac translations, some of which dated back to before the Arabconquests. One or the other (it is uncertain from the sources)translated theCategories, Ishâq translatedOnInterpretation, Hunayn seems to have collaborated with theotherwise unknown Theodorus to translate thePrior Analytics,father and son both seem to have had a hand in producing a new Syriactranslation of thePosterior Analytics, and Ishâqprovided revised translations oftheTopics and theRhetoric. Perhaps it was someonein this circle who translated thePoetics into Syriac.^[4]

In spite of these achievements, Hunayn's circle is not unequivocallyAristotelian. Hunayn himself was interested above all in Galen, andwhat we know of Galen's greatest logical work we know from citations inHunayn's reverential listing (Boudon 2000: 458On Demonstration).

1.2 Farabian Aristotelianism

Soon after, however, Baghdad philosophy was dominated by self-styledPeripatetics who presented themselves as reestablishing Aristotle'strue teachings after a period of rupture. The leading lights of thismovement were the Syriac Christian Abû Bishr Mattâ ibnYûnus (d. 940) and his younger Muslim colleague, AbûNasr Alfarabi (d. 950). In the early 900s, Abû Bishr addedtranslations from the Syriac of thePoetics and thePosteriorAnalytics to the growing ArabicOrganon. He and hiscolleagues also contributed to a commentary tradition on each componentof theOrganon.

Abû Bishr lumbers into every piece that has been written on thehistory of Arabic logic as the clumsy advocate of the view thatspeakers of Arabic need to learn Greek logic. In a disputation on therelative merits of grammar and logic convened for the amusement of theVizier, he confronts a dashing young opponent,Sîrâfî, who confounds him with a series ofgrammatical subtleties. To these, Abû Bishr responds:

This is grammar, and I have not studied grammar. Thelogician has no need of grammar, whereas the grammarian does needlogic. For logic enquires into the meaning, whereas grammar enquiresinto the expression. If, therefore, the logician deals with theexpression, it is accidental, and it is likewise accidental if thegrammarian deals with the meaning. Now, the meaning is more exaltedthan the expression, and the expression humbler than the meaning.^[5]

Whatever the merits of Abû Bishr's view of the relation of logicto language, it weathered Sîrâfî's storm ofcriticism badly. Assessments differ as to what we should learn fromthis discussion,^[6]but it serves at least to show that some were sceptical of the utilityof Aristotelian logic. Other Muslim scholars went further thanSîrâfî and considered the study of logic impious,mainly because of its association with metaphysics. As one fideistscholar put it many years later, “the access to something bad isalso bad” (Ibn as-Salâh (d. 1245), quoted in Goldziher1981: 205–206).

It was Abû Bishr's younger colleague, Alfarabi, who was theoutstanding contributor to the Aristotelian project, though not as atranslator (see now Rudolph 2012). On the question of the relation oflogic to language, Alfarabi offers a view somewhat more nuanced thanAbû Bishr's (see 2.1.1 below). He alsoclaimed that logic was indispensable for analysing the argument-formsused in jurisprudence and theology, a claim that was to be taken up acentury later by Abû Hamid al-Ghazâlî(d. 1111), thereby preparing the way to introduce logic into themadrasa (see 1.4.1 below). To support his claim,Alfarabi wroteThe Short Treatise on Reasoning in the Way of theTheologians.

…in which he interpreted the arguments of thetheologians and the analogies (qiyâsât) of thejurists as logicalsyllogisms in accordance with the doctrines of the ancients.^[7]

But Alfarabi's main contribution to the Aristotelian project was aseries of commentaries on the books of theOrganon—manyof themsadly lost—which represent the finest achievement in the study ofAristotelian logic in Arabic. His work in this area aims at the LesserHarmony, the “project of forging a single, consistent doctrineout of the sometimes incongruent theories found in Aristotle's manytreatises;” and this marks him out as clingingto a major hermeneutical commitment of late antiquity (see Wisnovsky2003: 15, 266). The quality of Alfarabi's arguments is clear from hisremaining long commentaries on Aristotle.^[8] He is the first truly independent thinkerin Arabic logic, a fact commemorated by the honorific bestowed upon himby Avicenna: the Second Teacher (after Aristotle). When Avicenna laidout his own syllogistic, he noted each point on which he differed fromAlfarabi (Street 2001).

The tradition with which Alfarabi was associated, a tradition centredon exegetical problems in theOrganon, reached its crowningachievement—a superb and heavily glossed translation oftheOrganon^[9]—at the same time that Avicenna wassetting about his work in the East, work which was to maketheOrganon irrelevant for the vast majority of subsequentArabic logicians.

This is a watershed moment: the Farabian tradition continued its workon the Aristotelian texts, though ever more defensively and reactivelyto challenges posed by Avicenna. The Avicennan tradition by contrastsimply ignored the Aristotelian texts. The Farabian tradition shrankaway so quickly that even by the late twelfth century, to studyFarabian logic meant traveling to North Africa.^[10] Spain and NorthAfrica were its last strongholds, and the work of Averroes (see 1.4.2 below) is best understood as acommentary on Aristotle determined in its focus and direction by thecriticisms of Avicenna.

1.3 Avicennan Aristotelianism

At the same time that the Baghdad philosophers were finalizing thetranslation of theOrganon and furnishing it with extensiveglosses, Avicenna (d. 1037) was beginning his career far away inthe east, in Khurasan. His style of philosophy was to make theAristotelian texts irrelevant for the dominant tradition of Arabiclogic after him. Led by his Intuition,^[11] he presented himself as anautodidact able to assess and repair the Aristotelian tradition. In other words,Avicenna's doctrine of Intuition delivered him an Aristotelianismunfettered by the hermeneutic commitments of the Lesser Harmony.

In the modal logic, for example (a subject voluminously contested inthe Arabic tradition;see 2.3 below), he cut through the problems inthe Aristotelian account by taking them either as tests of thestudent's acuity, or mistakes by Aristotle in implementing principles.Here is what he says in theSyllogism of theCure,written about midway through his career:

You should realize that most of what Aristotle's writingshave to say about the modal mixes are tests, and are not genuineopinions—this will become clear to you in a number ofplaces… (AvicennaQiyâs [1964]204.10–12)

In his later writings, Avicenna is less solicitous in explaining awaywhat he regards as inconsistencies in Aristotle's syllogistic, andwrites of problems in thePrior Analytics as arising throughnegligence; an example of such a text isTwenty Questions,which I think is written on the eve of Avicenna's Eastern period(Street 2010: 100–103; see periodization in Gutas 1988: 144). Itconsists of answers to questions on syllogistic sent by the learned menof Shiraz (and thus shows how odd Avicenna's systemmust have seemed to his contemporaries). Why, they ask, has Avicennaproduced a syllogistic system that differs so radically fromAristotle's? At various points, we find Avicenna presenting Aristotle'sdecisions (about mixes with possibility propositions as minor premises)as failures to implement general principles (Avicennaal-Masâ‘il al-Gharîba: [1974] 94.14, 94.20, 94.22, 95.5,95.11).

Avicenna's Intuition not only set aside important parts of Aristotle'slogic, it also differed from Alfarabi's interpretation of that logic.Avicenna has, however, more consistently courteous ways of decliningto follow Alfarabi. He refers to Alfarabi as the “eminent laterscholar to whom we are most concerned to direct our remarks” ashe constructs his different system (see Street 2001).

For a general overview of Avicenna's logic, there is now an Englishtranslation of the logic of Avicenna'sSalvation (see Avicenna2011a). But of all his many works,^[12] it is Avicenna'sPointers and Reminders that had most impact on subsequent generations oflogicians. It became, as Ibn Taymiyya declared, the Koran of thephilosophers (Michot 2000: 599). From it we may note a few broad buttypical differences from thePrior Analytics in thesyllogistic. First, the “absolute” (mutlaqa,often translated “assertoric”) propositions havetruth-conditions stipulated such that they are temporally modalised (byan elided “at least once”, so that, for example, the contradictory ofan absolute is not an absolute, absolute e-propositions do not convert,second-figure syllogisms with absolutepremises are sterile;see also 2.3.1 below). Secondly, Avicenna beginsto explore the logical properties of propositions of the formeveryJ isB whileJ. Thirdly, Avicenna divides syllogistic into connective (iqtirânî)and repetitive (istithnâ‘î) forms, a divisionwhich replaces the old one into categorical and hypothetical (Avicennaal-Ishârât [1971] 309, 314, 374).

According to what wehave verified ourselves, the syllogism forms two divisions, connectiveand repetitive. Theconnective is that in which one of the two sides of the contradictionin which we find the conclusion does not appear [in the premises]explicitly, but only potentially… The repetitive is that inwhich [the conclusion or its contradictory] does explicitly appear.(Avicennaal-Ishârât [1971] 374)

Asa rough guide, we may call a logician “Avicennan” if headopts these doctrines.Pointers was not the only importantAvicennan text in later Arabic logic: post-Avicennan logicians minedtheCure's volume on thePrior Analyticsfor the syllogistic with conditional premises, a syllogistic which theymodified perhaps even more than they modified Avicenna's modal syllogistic(see Khûnajî 2010: section 10; see also El-Rouayheb'sIntroduction, xlv–xlviii).

1.4 Logic in the Twelfth Century

The twelfth century is one of the most complex periods oftransformation in Muslim intellectual history. The century before hadseen the advent of the madrasa as the prime institution of learning inthe Islamic world (Makdisi 1981: 27–32, especially 31), and AbûHâmid al-Ghazâlî (d. 1111) had been appointed tothe most prestigious of these new institutions. One of the most reveredMuslim thinkers of all time, he took up Alfarabi's arguments in supportof the utility of logic for theology and law, especially in his lastjuridical summa,Distillation of the Principles of Jurisprudence,a text which soon became a mainstay of the madrasa. The late twelfthcentury also saw Averroes produce what was effectively the last of thework in the Farabian tradition of logic, work which was to betranslated into Hebrew and Latin but which was, with minor exceptions,neglected by Arabic logicians. Finally, through the course of thetwelfth century, the modified Avicennan logic that would be adopted bythe logic texts of the madrasa began to emerge.

1.4.1 Ghazâlî and Logic

Before, and especially through, the tenth and eleventh centuries, adeal of effort was expended in defining which sciences constitute theproper focus of a scholar's education and how these sciences relate toeach other. A fourteenth-century polymath divided the sciences ofcivilization into those “natural to man and to which he is guidedby his own ability to think, and a traditional kind that he learns fromthose who invented it.” (Ibn-KhaldûnMuqaddima [1858]2:385). Earlier scholars had made a parallel distinction between theForeign Sciences and the Islamic Sciences. Philosophy wasthe preeminent science of the first kind, and theology andjurisprudence sciences of the second. Although logic was originallypart of philosophy, and due to this association despised by manytheologians and jurists (noted above in 1.2), a change in attitude cameabout in the twelfth century:

It should be known that the early Muslims and the earlyspeculative theologians greatly disapproved of the study of thisdiscipline. They vehemently attacked it and warned against it. Theyforbade the study and teaching of it. Later on, ever sinceGhazâlî (d. 1111) and Fakhraddînar-Râzî (d. 1210), scholars have been somewhat morelenient in this respect. Since that time, they have gone on studyinglogic, except for a few who have recourse to the opinion of theancients concerning it and shun it and vehemently disapprove of it(Ibn-KhaldûnMuqaddima [1858] 113.13-u; cf.Ibn-Khaldûn1967: 3:143–144).

Ghazâlî had most impact in this regard (see Rudolph2005). I deal with Râzî's contribution below (see 1.5.1).

Ghazâlî argued that, properly understood, logic wasentirely free of metaphysical presuppositions injurious to the faith.This meant that logic could be used in forensic reasoning:

We shall make known to you that speculation in juristicmatters (al-fiqhiyyât) is not distinct from speculationinphilosophical matters (al-‘aqliyyât) in terms ofits composition,conditions, or measures, but only in terms of where it takes itspremises from (GhazâlîMi‘yâr [1961]28.2–4).

Ghazâlî tended to an even stronger position towards the endof his life: more than being merely harmless, logic was necessary fortrue knowledge. Here is what Ghazâlî has to say at thebeginning of his famousDistillation of the Principles ofJurisprudence (referring back to two of his earlier works onlogic):

In this introduction we mention… the condition oftrue definition and true demonstration and their divisions in aprogram more concise than what we set out in ourTouchstone forSpeculation andYardstick of Knowledge [respectively,Ghazâlî 1966 and Ghazâlî 1961]. Thisintroduction is not part of the sum of the science of [juristic]principles, nor among the preliminaries particular to it; rather it isan introduction to all the sciences, and he who does not comprehend[logic] is not to be trusted at all in his sciences.(GhazâlîMustasfâ [1322 AH] 10.15–17)

For all his historical importance in the process of introducing logicinto the madrasa, the logic that Ghazâlî defended was toodilute to be recognizably Farabian or Avicennan.

1.4.2 Averroes and the End of Textual Aristotelianism

Averroes was one of the last representatives of a dyingAristotelianism that bent all its efforts to the task of the LesserHarmony, reconciling all of Aristotle's texts with each other. Astudent of the Baghdad philosophy that had beentransplanted to al-Andalus (Dunlop 1955), Averroes was trained in thelogic of Alfarabi, many specifics of which he later came to discard:

One of the worst things a later scholar can do is todeviate from Aristotle's teaching and follow a path other thanAristotle's—this is what happened to Alfarabi in his logicaltexts… (AverroesMaqâlât [1983]175.6–8)

For Averroes, Alfarabi's attempts to make sense of the difficulties inAristotle's texts were too weak to anticipate and answer Avicenna'scriticisms. In one such area, the modal logic, Averroes was to returnto the problems four times through his career (see Elamrani-Jamal1995), and near the end of his life, having assessedthe problems in his colleagues' interpretations, he wrote:

These are all the doubts in this matter. They keptoccurring to us even when we used to go along in this matter with ourcolleagues, in interpretations by virtue of which no solution to thesedoubts is clear. This has led me now (given my high opinion ofAristotle, and my belief that his theorization is better than that ofall other people) to scrutinize this question seriously and with greateffort. (AverroesMaqâlât [1983] 181.6–10)

Averroes' project in its full flowering is driven by the demands ofthis rigorously construed Lesser Harmony and—in spite ofeverything—by Avicenna's increasingly popular reformulation ofAristotelian doctrine. Both aspects of the Averroist project are infull evidence in hisPhilosophical Essays,a number of which are on logical matters. So, for example, Averroesdefends and refines Alfarabi's account of the conversion of modalpropositions against Avicenna's attack, and then uses that account asthe basis of a new interpretation of the modal syllogistic (see Thom2003: chapter 5, working with fourth system described inElamrani-Jamal 1995). A second example of the way Averroes works ishis reappraisal and vindication of Aristotle's doctrines of thehypothetical syllogistic against Avicenna's alternative division intoconnective and repetitive syllogisms (see AverroesMaqâlât [1983]essay 9, 187–207). Those Arabic logicians who make use of Averroes tendto come from North Africa, or from Persia at certain moments ofnostalgia for a time before the coming of the great logicians of thethirteenth century (see section 1.6 below). Further, Averroes' deepconcern with the Aristotelian texts made his work transportable to bothHebrew and Latin philosophical traditions.

1.4.3 The Avicennan Tradition of the Twelfth Century

But the work on logic which was both technically advanced (andtherefore unlike Ghazâlî's) and influential on later Arabiclogicians (and therefore unlike Averroes') was done by Avicennanlogicians who had begun to repair and reformulate Avicenna's work. Justas Avicenna had declared himself free to reworkAristotle as Intuition dictated, so too these logicians working onAvicenna's logic regarded themselves as free to repair the Avicennansystem as need arose, whether from internal inconsistencies, or fromintellectual requirements extrinsic to the system. A major earlyrepresentative of this trend is ‘Umar ibn Sahlânas-Sâwî (d. 1148) who began, in hisLogicalInsights for Nasîraddîn, to rework Avicenna's modalsyllogistic.^[13]It was to be his students and their students, however, who would go onto make the final changes to Avicennan logic that characterized thesubject that came to be taught in the madrasa.

1.5 The Avicennan Tradition in the Madrasa and Beyond

Ghazâlî had successfully introduced logic into the madrasa(though it was studied in other venues as well (Endress 2006)). Whathappened to it after this time was the result of the activities oflogicians much more gifted than Ghazâlî. This period hastentativelybeen called the Golden Age of Arabic philosophy (Gutas 2002). It isin this period, and especially in the thirteenth century, that themajor changes in the coverage and structure ofAvicennan logic were introduced; these changes were mainly introducedin free-standing treatises on logic. It has been observed that thethirteenth century was the time that “doing logic in Arabic wasthoroughlydisconnected from textual exegesis, perhaps more so than at any timebefore or since” (El-Rouayheb 2010b: 48–49). Many of the majortextbooks for teaching logic in later centuries come from thisperiod.

1.5.1 Râzî and Khûnajî

In the fourteenth century, Ibn Khaldûn (d. 1406) noted theways that Arabic logic had changed from the late twelfth century on (hementions a growing restriction of the subject to the syllogistic,and a concentration on the formal aspects of logic;see Text 14, 2.2.3 below), and names the scholars he thinks are responsible for the change.

Treatment of [the subject as newly conceived] has becomelengthy and wide-ranging—the first to do this wasFakhraddîn ar-Râzî (d. 1210) and, after him,Afdaladdîn al-Khûnajî (d. 1248), on whom Easternscholars rely even now… The books and ways of the ancients havebeen abandoned, as though they had never been (Ibn-KhaldûnMuqaddima [1858] 113; cf. Ibn-Khaldûn 1967: 3:143).

Let us consider the nature of the work of the first logician named,Fakhraddîn ar-Râzî. Recent scholarly efforts haveseen a number of Râzî's important works published, butthere has been relatively little analysis of his logic, with theexception of the commentary on hisCompendiumby A. Karamaleki & A. Asgharinizhad (see the second half ofRâzî 2002). His teacher in logic was Majdaddînal-Jîlî, who may have been Sâwî's student.^[14] In spite of thispedigree, the polite manner of correcting Avicenna's system that wefind in Sâwî's work is missing from Râzî's. InGistof Pointers, Râzî sets out his own remarkably compactaccount of the modals, and then says of Avicenna's exposition:

When you have understood what we have mentioned, you willcome to realise that [my book], in spite of its brevity, is moreexplanatory and better verified than what is found in [Pointers],inspite of its length. (RâzîLubâb [1355AH] 22.14–15)

For all his dismissive comments, Râzî's logic is above alla development of the logic ofPointers,presented in ways that derive from Avicenna's methods of exposition.One way to understand thirteenth-century Arabic logic, at least thelogic developed in Persia and surrounding territories, is asattempts to solve the dialectical aporia set up by Râzî; anexample of this dynamic will be given insection 2.3 below. And thisisAvicennan logic: Râzî, like Sâwî,never refers to an Aristotelian text, and refers to Alfarabi in such afashion as to suggest that he is simply paraphrasing Avicenna'sreferences.

It is the second logician Ibn Khaldûn mentions who, it wouldseem, made more, and more substantive, changes to Avicennan logic:Afdaladdîn al-Khûnajî (d. 1249). His major workon logic, theDisclosure of Secrets about the Obscurities ofThoughts,has recently been edited (KhûnajîKashf [2010], with a longintroduction including a biography of thisimportant logician, and an overview of some of his more importantinnovations). He was described, probably pretty loosely, as one ofRâzî's students; Bar Hebraeus writes ofa group who were famed as “authors of major works on logic andphilosophy… [among them] Khûnajî in Cairo”(translated in Pococke 1663: 485.7–13 (Arabic)). The sense in which hecould have been Râzî's student is presumably that hestudied under someone who had studied under Râzî. It willbe some time before we are able to assess Khûnajî'simportance accurately; he seems to have exercised extraordinaryinfluence, oftentaking a strong stand against both Râzî's position andAvicenna's. In their different ways, both the North African and theEastern traditions oflogic are strongly influenced by Khûnajî (see section 1.6 below).

1.5.2 Tûsî and the Maragha School

Khûnajî'sDisclosure inspired work by other greatEastern logicians not mentioned by Ibn Khaldûn, namely,Athîraddîn al-Abharî (d. 1265) andNajmaddîn al-Kâtibî (d. 1276). Bar Hebraeusclaims that Abharî was also one of Râzî's students,though as in the case with Khûnajî, opportunity for directcontact must have been virtually non-existent. Kâtibî wasAbharî's student. So too, perhaps, was the greatShî‘î scholar Nasiraddîn at-Tûsî(d. 1274); at any rate, he had read Râzî's commentaryon Avicenna'sPointers under Abharî (Endress 2006:411). These three men are among the greatest logicians workinganywhere in the thirteenth century. Two of them, Kâtibîand Abharî, produced the two texts which became mainstays of themadrasa teaching of logic, studied from the late thirteenth centurydown to the present day: theÎsâghûjîand theShamsiyya (see Calverley 1933 andKâtibî 1948).

All three were also involved in a major intellectual projectestablished by the îl-Khânid rulers in 1259: the MaraghaObservatory. Tûsî had been given the task by the Mongols ofsetting up an astronomicalobservatory, and he asked Kâtibî (among others) to helphim. At some stage in the early years of the observatory, Abharîjoined them. We know that Kâtibî was teaching bothRâzî'sCompendium and Khûnajî'sDisclosureto students during this period, and that Abharî andTûsî were debating how best to deal with the challengesraised by Khûnajî to Avicenna's logic. Kâtibî'smajor works on logic (a long treatise,Summa of Subtle Points,and the textbook, theShamsiyya)were written after these discussions, and used many of the argumentsraised in them. Kâtibî'sShamsiyyawas commented on by Qutbaddîn at-Tahtânî(d. 1365), among many others (for details about these othercommentaries, see Schmidtke 1991, 2013; Wisnovsky2004). Tahtânî's commentary records a great many of thetechnical debates going on among the scholars at the Maraghaobservatory. Kâtibî's textbookand Tahtânî's commentary together constitute theimpressivepreparation most Muslim scholars underwent in logic.

Tûsî is a particularly interesting logician in termsof his historical affiliations. He had come to Avicenna'sPointersby way of Râzî's students, but he developed a deeperrespect for Avicenna's formulations than any of his contemporaries.Râzî's hostility in characterizing the Avicennan expositioninPointers is confronted by Tûsî inSolutionto the Difficulties of Pointers. The nature of Tûsî'sresponse to Râzî is generally taken to be entirelynegative—he relayed a description of Râzî's work asbeing “a butchery, not a commentary”—but in factTûsî acknowledged the value of Râzî's work. Therhetorical engagement with Râzî is really part of a broadercampaign to defend not only Avicenna's logic but also his exposition ofthat logic. To take one example: Avicenna's account of different kindsof absolute proposition had long raised questions among post-Avicennanlogicians. Tûsî explains why Avicenna explores it the wayhe does:

What spurred him to this was that in the assertoricsyllogistic Aristotle and others sometimes used contradictories ofabsolute propositions on the assumption that they are absolute; andthat was why so many decided that absolutes did contradict absolutes.When Avicenna had shown this to be wrong, he wanted to give a way ofconstruing those examples from Aristotle. (TûsîSharh al-Ishârât [1971] 312.5–7)

It is in his other works that Tûsî took a more solidstand against substantive changes proposed for Avicennan logic,especially in hisSetting the Scale for an Evaluation of“Revealing Thoughts”, an extended assessment ofAbharî'sRevealing Thoughts (Tûsî 1974b),in which Abharî adopted a number of Khûnajî'spositions. Here wefind not merely a sympathetic exposition of Avicennan logic as Avicennawould have wanted it to be understood, but a reasoned attackon the thinking behind alternative proposals. Tûsî went onwith this project in a series of exchanges with Kâtibî(Tûsî 1974a).

Among his other works, Tûsî wrote theBook ofAbstraction as a non-polemical exposition of logic. His famous andinfluential student, al-‘Allâma al-Hillî(d. 1325), who had also studied under Kâtibî, wrote acommentary on it, theFacetted Jewel on the Book of Abstraction(Hillî 1363 SH). It is only relatively recently (the latenineteenth century) that the text and commentary were printed and cameto be used in Shî‘î seminaries to introduce logic(El-Rouayheb 2010b: 108 n77). On the face of it, the text is quiteconservatively Aristotelian, itsrubrics following the traditional course of topics covered in theOrganon,and in the same order; for all that, the substantive doctrine seems on thewhole to be pristine Avicennan, precisely the doctrine Tûsîdefended against Râzî, Khûnajî, Abharîand Kâtibî.

1.5.3 Logic and the Madrasa

The texts of Abharî and Kâtibî were used in themadrasa by Sunnis and Shî‘îs (though theShî‘îs turned to the texts of Tûsî andHillî in the nineteenth century). But the tradition was much moredynamic than the entrenchment of these texts in the syllabus wouldsuggest. First, whatever introductory texts were used in teaching thediscipline,it is clear that students who were attracted to logic studied wellbeyond these texts with teachers at the madrasa who were often engagedto teach other subjects. Secondly, other places such as hospitals andobservatories provided less formal venues for the advanced study oflogic (see Endress 2006).

But it was the madrasa that provided the backbone of the tradition,and a number of jurists came time and again to stress that the study oflogic was so important to religion as to be afard kifâya,that is, a religious duty such that it is incumbent on the community toensure at least some scholars are able to pursue its study.

As for the logic that is not mixed with philosophy, as in… the treatise of Athîraddîn al-Abharîcalledîsâghûjî and the works ofal-Kâtibî [i.e.,ash-Shamsiyya] andal-Khûnajî [Afdaladdîn (d. 1249),i.e.,al-Jumal] and Sa‘daddîn[at-Taftâzânî, i.e.,Tahdhîbal-Mantiq], there is no disagreement concerning thepermissibility of engaging in it, and it is rejected only by he whohas no inkling of the rational sciences. Indeed, it is afardkifâya because the ability to reply to heretical views inrational theology (kalâm), which is afardkifâya, depends on mastering this science, and that whichis necessary for a religious duty is itself a religiousduty.^[15]

Of course, afatwâ like this invites us to considerwhat logic mixed with philosophy might look like; one scholarmentioned in the study just quoted offersBaydâwî'sAscending Lights as such a logic(Baydâwî 2001). Baydâwî's logic itself seemsharmless—a generalized Avicennan logic—, but it is placeddirectly before an exposition of a speculative theology stronglyinfluenced by Avicennan philosophy. Different scholars would have helddifferent positions, but for thefatwâ quoted,perhaps the context surrounding a logic text is all that matters inmaking it acceptable or not.

1.6 The Delineation of Logical Traditions

After 1350 or so, logical traditions began to crystallise, often ona regional basis. Recent studies by El-Rouayheb (2010b) and Ahmed(2012) have provided preliminary sketches of the seven or so centuriesof logical activity. Especially El-Rouayheb (2010b) makes it clearthat we cannot assume that there is a point at which original workstops and the tradition begins simply to restate ancient results. Itis true that much of the later material is, unlike the bulk of thethirteenth-century material, presented as commentary. There is atemptation to conclude from this that there was a decline in logicalstudies in the realms under Muslim control that corresponds with thesixteenth-century decline of the subject in early modern Europe; sucha conclusion is seemingly supported by a tradition of scholarshipdevoted to a luxuriation of layered commentary on a five hundred yearold primary text. But genre by no means dictates content, and we oftenfind original work presented in this way.^[16]

Regionalism had been a significant factor especially in thetradition of logic studied in al-Andalus; more generally, thecrystallisation of traditions after Khûnajî also tended tobe regional. Although Khûnajî was read in North Africa, itwould seem that the Maragha logicians were not read there, at leastnot systematically. By contrast, Averroes was still read and taught inNorth Africa up to the end of the fourteenth century, and so IbnKhaldûn would have been taught Averroes as well as a decoctionof Khûnajî's logic; his teacher, Muhammad al-Sharîfal-Tilimsânî (d. 1370), had written a substantialcommentary on a short work by Khûnajî,theSentences (El-Rouayheb 2010b: 71–79).

At this stage of research, early modern logictraditions may best be divided along the fault-lines of the greatempires: Ottoman, Persian, and Indian. All of these traditions producedmassive amounts of work. With respect to the Persian tradition, I wouldnote merely that by the advent of the Safavids (1501), thephilosophical tradition was galvanized by a dispute between two leadingscholars that had ground on for the last quarter of the precedingcentury, and this marked a point at which it became philosophicallyrespectable to prefer the ancient scholars to the more recent, and Averroesenjoyed a revival of interest from time to time as a result (seeEl-Rouayheb 2010b: 92–104 for one aspect covered in the dispute, andPourjavady 2011: “Introduction” for the background). In theOttoman tradition, we find a flurry of impressive activity after 1600among logiciansdealing with relational syllogisms (presented in El-Rouayheb 2010b:chapters 5, 6 & 7). Finally, with respect to the India, recentresearch shows the complexities of the formation ofteaching traditions of logic there (sketched in Ahmed 2012).

The coming of the metropolitan powers signals a convenient point atwhich we may speculate that important new possibilities opened up inArabic logic. At least some members of the Christian communities inthe capitulated territories in Syria and Lebanon trained in Europe. Ifthe books on logic they wrote in Arabic were simply Western logic,then their works fall outside the purview of this entry; but I notethat Butrus al-Tûlâwî (d. 1745) in his1688Introduction gives a definition of the syllogism whichcomes from Khûnajî (see Khûnajî 2010:238.13–14), which is presumably the result of a syncretic process ofgreat interest for the history of Arabic logic (pace El-Rouayheb2010b: 114ff). Again, the relevant texts must be edited and studied.^[17]

2. Logical Doctrines under Dispute

Of many possible candidates for consideration, the discussions aroundthree logical doctrines seem to me to be particularly instructive. Thefirst has to do with the subject matter of logic, something whichneeds to be identified if there is any prospect of presenting logic asa science (something most parties to the debate at least claim towant). The doctrine associated with Avicenna as to the subject matterof logic came to have decisive impact in the Latin logical tradition,though it was not the only doctrine in play through the later Arabictexts. The second and related set of doctrines has to do with offeringan account of how the various logical disciplines—demonstration,dialectic, rhetoric and poetics—fit together. Inheritedexpectations of what disciplines a logical treatise should cover cameunder pressure from new disciplines derived from grammar and law;ultimately, the disciplines of dialectic, rhetoric and poetics were nolonger treated in the ways they had been in the Aristoteliantradition. Finally, modal syllogistic was perhaps the most keenlydisputed topic in logic through the twelfth and thirteenth centuries,and I offer an overview of one line of discussion which took place. Ilook in particular at arguments coming from eastern Iran in thethirteenth century—a tradition I call Maragha logic (see 1.5.2 above)—because this was a period of particularly intenselogical activity culminating in textbooks overwhelmingly important inthe subsequent teaching of the discipline.

Let me go on immediately to acknowledge that these may not be themost philosophically sophisticated or historically representativediscussions which took place in the Arabic tradition (see e.g., Hodges2011a (inOther Internet Resources) on the subject matter oflogic). They do however all have the advantage of having beendiscussed by a number of Arabic logicians through the centuries, andof having been the subject of at least some academic study. Othercandidate topics illustrate what I seek to avoid. Consider theimpressive work by Avicenna on proof theory which has been translatedand analysed by Hodges (2009,Other Internet Resources); to the extentthat I can follow this work, it exhibits a truly extraordinary levelof logical acumen. At the same time I have never—in myadmittedly narrow reading in the tradition—seen another logiciandevelop or even use Avicenna's results in this area. In short, thetopic illustrates Avicenna's logical genius rather than a common themerunning through Arabic logic.

Consider next the work in the Avicennan tradition on syllogismswith conditional and disjunctive premises (see 1.3 above). Thisimportant material is original to Avicenna, used among other things in theanalysis of the reductio argument. If we consultKhûnajî'sDisclosure, we find one quarter of thework's four hundred pages given over to syllogisms with conditional ordisjunctive premises, developing the subject far beyond Avicenna'soriginal insights in theCure (and often in a manner fairlydismissive of Avicenna's work). Khûnajî clearly looked onhis modifications to this part of Avicenna's logic as central to hisproject, and his modifications were adopted by later logicians likeKâtibî. If anything, this would be a better topic than themodals to illustrate the distinctive characteristics of thediscussions that went on in Arabic logic. In the present state of thefield, however, although there have been major studies of Avicenna'ssyllogistic with hypothetical premises (e.g., Rescher 1963c; Shehaby1973; Gätje 1985), there is none at all—to the best ofmy knowledge—on its reception and modification in the subsequenttradition. One or both of these reasons (that is, neglect by thesubsequent tradition and neglect in the secondary literature) rule outother major topics such as the theory of demonstration and what mightbe called meta-syllogistic (but see, on the first, Hasnawi 2008;Strobino 2010, 2012; and on the second, El-Rouayheb2009; Hodges 2011c (inOther Internet Resources)).

2.1 The Subject Matter of Logic

It is common doctrine among medieval Latin logicians that logic is alinguistic science. An associated doctrine is that logic makes up,with grammar and rhetoric, the trivium, or the three arts of language.There never was a trivium in the Arabic-speaking philosophical world,and when scholars spoke of the “three arts”(as-sinâ‘ât ath-thalâth), they werereferring to demonstration, dialectic and rhetoric. Clashes betweenscholars working on Greek texts and scholars working on the Arabiclanguage first served to pose the question of how logic related tolanguage, and specifically to the Arabic language. This in turn forcedthe discussion of what the subject matter of logic is, and how itssubject matter differed from that of grammar.

2.1.1 Expressions, Meanings and Intelligibles

The unpromising proposal made by Abû Bishr Mattâ inresponse to Sîrâfî's attack on logic (see 1.2 above)prompted Alfarabi to make a second attempt at explaining how logic,grammar and language relate to each other.

Text 1. This art [of logic] is similarto the art of grammar, in that the relation of the art of logic to theintellect and the intelligibles is like the relation of the art ofgrammar to language and expressions (al-alfâz). That is,to every rulefor expressions which the science of grammar provides us, there is ananalogous [rule] for intelligibles which the science of logic providesus.^[18]

This allows Alfarabi to go on to characterize the subject matter oflogic as follows:

Text 2. The subject matters (mawdû‘ât)of logic are the things for which [logic] provides the rules, namely,intelligibles in so far as they are signified by expressions, andexpressions in so far as they signify intelligibles.

…

[Logic] shares something with grammar in that it providesrulesfor expressions, yet it differs in that grammar only provides rulesspecific to the expressions of a given community, whereas the scienceof logic provides common rules that are general for the expressions ofevery community.^[19]

This is to say—and here I follow Black's characterization ofthe doctrine—logic is something of a universal grammar or, morestrictly, providing a universal grammar is one of the tasks of logic.Other philosophers of the Baghdad school like Yahyâ ibn‘Adî (d. 974) by and large adopt Alfarabi's doctrine(see Endress 1977, 1978; cf. Black 1991: 48ff). (I think Alfarabi wasbeing impelled towards holding that the subject matter of logic issecondary intelligibles, and perhaps ultimately came to hold such adoctrine (see Menn 2012: 68; AlfarabiKitâbal-Hurûf [1970] 64, 66–67), but the positiondescribed above represents the doctrine Avicenna was to reactagainst.)

2.1.2 Secondary Intelligibles

Aspects of this attempt to identify the subject matter of logicinvite clarification. First, is the intelligible corresponding to, say,“horse”, part of the subject matter of logic? Secondly, isreference to expressions essential in a definition of logic, as issuggested by the phrase “intelligibles in so far as they aresignified by expressions”?

A more careful statement of what was probably much the samedoctrine is provided by Avicenna. Concepts like “horse”,“animal”, “body”, correspond to entities in thereal world, entities which can have various properties. In the realm ofthe mental, concepts too can acquire various properties, propertiesthey acquire simply by virtue of existing and being manipulated by themind, properties like being a subject, or a predicate, or a genus.These are the subject matter of logic, and it seems it is only mentalmanipulation that gives rise to these properties.

Text 3. If we wish to investigate thingsand gain knowledge of them we must bring them into conception(fî t-tasawwur); thus they necessarily acquire certainstates (ahwâl) that come to be in conception: we musttherefore consider those states which belong to them in conception,especially as we seek by thought to arrive at things unknown fromthose that are known. Now things can be unknown or known only inrelation to a mind; and it is in conception that they acquire whatthey do acquire in order that we move from what is known to what isunknown regarding them, without however losing what belongs to them inthemselves; we ought, therefore, to have knowledge of these states andof their quantity and quality and of how they may be examined in thisnew circumstance.^[20]

These properties that concepts acquire are secondary intelligibles;here is an exposition of thispart of Avicennan doctrine by Râzî:

Text 4. The subject matter of logic isthe secondary intelligibles in so far as it is possible to pass bymeans of them from the known (al-ma‘lûmât)to the unknown (al-majhûlât). The explanation of“secondary intelligibles” is that man conceives therealities of things (haqâ’iq al-ashyâ’) inthe first place, then qualifies some with others either restrictivelyor predicatively (hukman taqyîdiyyan awkhabariyyan). The quiddity's being qualified in this way issomething that only attaches to the quiddity after it has become knownin the first place, so it is a second-order [consideration](fî d-darajati th-thâniya). If theseconsiderations are investigated, not absolutely, but rather withrespect to how it is possible to pass correctly by means of them fromthe known to the unknown, that is logic. So its subject matter iscertainly the secondary intelligibles under the considerationmentioned above (RâzîMulakhkhas [2002]10.1–10.8; see now El-Rouayheb 2012: esp. 72–77 as to whetherRâzî's clarification is ultimately compatible withAvicenna's).

Avicenna in hisMetaphysics makes special mention ofthese secondary intelligibles.

Text 5. The subject matter of logic, asyou know, is given by the secondary intelligible meanings, based onthe first intelligible meanings, with regard to how it is possible topass by means of them from the known to the unknown, not in so far asthey are intelligible and possess intellectual existence ([anexistence] which does not depend on matter at all, or depends on anincorporealmatter).^[21]

In identifying the secondary intelligibles, Avicenna is able to placelogic within the hierarchy of the sciences, because it has its owndistinct stretch of being which is its proper subject matter.

So much for the first problem in Alfarabi's formulation of what thesubject matter of logic is. Avicenna also has a view on the secondproblem, the question of whether or not expression is essential to adefinition of logic and its subject matter.

Text 6. There is no merit in what somesay, that the subject matter of logic is speculation concerning theexpressions insofar as they signify meanings… And since thesubject matter of logic is not in fact distinguished by these things,and there is no way in which they are its subject matter, [such people]are only babbling and showing themselves to be stupid.^[22]

One reason for this is that in Avicenna's psychology, language as aset of discrete expressions is not essential for the intellect in itsoperations. Note, however, that whatever Avicenna's official doctrineis, he recognizes and attempts to deal with the close nexus betweenlanguage and thought.

Text 7. Were it possible for logic to belearned through pure cogitation, so that meanings alone would beobserved in it, then this would suffice. And if it were possible forthe disputant to disclose what is in his soul through some otherdevice, then he would dispense entirely with its expression. But sinceit is necessary to employ expressions, and especially as it is notpossible for the reasoning faculty to arrange meanings withoutimagining the expressions corresponding to them (reasoning beingrather a dialogue with oneself by means of imagined expressions), itfollows that expressions have various modes (ahwâl) onaccount of which the modes of the meanings corresponding to them inthe soul vary so as to acquire qualifications (ahkâm)which would not have existed without the expressions. It is for thisreason that the art of logic must be concerned in part withinvestigating the modes of expressions… But there is no valuein the doctrine of those who say that the subject matter of logic isto investigate expressions in so far as they indicatemeanings…but rather the matter should be understood in the waywe described.^[23]

As Sabra says, Avicenna seems to hold that “the propertiesconstituting the subject matter of logic would be inconceivable withoutthe exercise of a particular function of language” (Sabra 1980:764).

2.1.3 Conceptions and Assents

Avicenna's doctrine on the subject matter of logic was not adoptedby the majority of logicians who followed him (pace Sabra 1980: 757).Quite the contrary, Khûnajî claimed in the second quarterof the thirteenth century that the subject matter of logic wasconceptions and assents, a claim which was energetically resisted byremaining Avicennan purists like Tûsî. A recent study hasclarified what is at issue in this debate (El-Rouayheb 2012).

To understand the background to Khûnajî's claim, it isnecessary to bear two points in mind. The first is Avicenna's doctrineconcerning the states of knowledge that logic aims at producing:conception and assent.^[24]The second is what is means for somethingto be a subject of an Aristotelian science.

Text 8. […] A thing is knowable intwo ways: one of them is for the thing to be merely conceived(yutasawwara) so that when the name of the thing is uttered,its meaning becomes present in the mind without there being truth orfalsity, as when someone says “man” or “dothis!” For when you understand the meaning of what has been saidto you, you will have conceived it. The second is for the conceptionto be [accompanied] with assent, so that if someone says to you, forexample, “every whiteness is an accident,” you do not onlyhave a conception of the meaning of this statement, but [also] assentto it being so. If, however, you doubt whether it is so or not, thenyou have conceived what is said, for you cannot doubt what you do notconceive or understand… but what you have gained throughconception in this [latter] case is that the form of this compositionand what it is composed of, such as “whiteness” and“accident,” have been produced in the mind. Assent,however, occurs when there takes place in the mind a relating of thisform to the things themselves as being in accordance with them; denialis the opposite of that.^[25]

Note that an assent is not merely the production of a proposition bytying a subject and predicate together; “Assent, however, occurswhen there takes place in the mind a relating of this form to thethings themselves as being in accordance with them.” Allknowledge, according to Avicenna, is either conception orassent. Conception is produced by definition, assent by proof. AllAvicennan treatises on logic are structured in accordance with thisdoctrine: a first section deals with definition, which conduces toconception, a second with proof, which conduces to assent.

The subject of an Aristotelian science is investigated with a viewto identifying its per se attributes, that is, its necessary butnon-constitutive properties. The subject of geometry is spatialmagnitude and its species (such as triangle); finding, for example,that “internal angles summing to two right angles” belongs to“triangle” is the proper task of the science of geometry. If thesubject matter of logic is secondary intelligibles, then the propertask of logic will be identifying the per se attributes of secondaryintelligibles. According to Khûnajî, however, some of theproperties investigated by the logician are attributes of primaryintelligibles; in consequence, the subject matter of logic must besomething more general than secondary intelligibles. This promptedKhûnajî to declare that conceptions and assents are thesubject matter of logic. Kâtibî accepted this line ofreasoning:

Text 9. The logician may investigatematters that do not accrue to second intentions at all… but rather tosingle notions (ma’ânî)that occur in the mind. For he investigates the concept of “essential”,“accidental”, “species”, “genus”, “differentia”, “subject” and“predicate” and other things that accrue to single notions that weintellect.^[26]

Another logician who followed Khûnajî in thiswas Abharî; here is his statementof the doctrine:

Text 10. The subject matter of logic, Imean, the thing which the logician investigates in respect of itsconcomitants in so far as it is what it is, are precisely conceptionsand assents. [This is] because [the logician] investigates whatconduces to conception and what the means [to conception] depends upon(for something to be universal and particular, essential andaccidental, and such like); and he investigates what conduces toassent and what the means to assent depends upon, whether proximately(like something being a proposition or the converse of a propositionor the contradictory of a proposition and such like) or remotely (likesomething being a predicate or a subject). These are states whichinhere in conceptions and assents in so far as they are what they are.So certainly its subject matter is conceptions and assents.(TûsîTa‘dîl [1974b] 144.14–20)

And here is part of Tûsî's response:

Text 11. If what he means by conceptions and assentsis everything on which these two nouns fall, it is the sciences intheir entirety, because knowledge is divided into these two; whereuponwhat is understood from [his claim] is that the subject matter oflogic is all the sciences. Yet there is no doubt that they are not thesubject matter of logic…

[…]

The truth is that the subject matter for logic is the secondaryintelligibles in so far as reflection on them leads from the known to[understanding] the unknown (or to something similar, as do reductioarguments or persuasive arguments [146] or image-evoking arguments andthe like). And if they are characterised by the rider mentioned by themasters of this craft, conceptions and assents are among the set ofsecondary intelligibles in just the same way as definition andsyllogism and their parts, like universal and particular and subjectand predicate and proposition and premise and conclusion(TûsîTa‘dîl [1974b] 144.21–u,145.pu–146.3).

But as we have seen, for Tûsî's colleagues atMaragha, Avicenna'sidentification of secondary intelligibles as the subject matter oflogic excludes things which are properlyinvestigated in logic. (I note but do not attempt to cover thecounter-argumentsoffered in the later tradition against Khûnajî's position;see El-Rouayheb 2012: 82 et seq.)

2.2 The Contents of the Treatise on Logic

When the fullOrganon was finally assembled in Arabic, itincluded the whole range of texts in the order given them by theAlexandrian philosophers. There was an inherited expectation that thiswas the full and proper stretch of logical inquiry, an expectationwhich was to come under pressure in the Muslim world. It had alreadycome underrevision in Avicenna'sPointers and Reminders, but moresubstantial change was to follow.

One factor at work in determining the structure of Avicennan logictreatises was the doctrine of secondary intelligibles, a doctrine whichled to the exclusion of parts of theOrganon from the realmof the strictly logical, specifically, theCategories. Thearguments that excluded theCategories must also haveproblematized the inclusion of some other parts of theOrganon,such as theTopics.

Another factor at work was the doctrine of conceptions and assents.If,as was commonly accepted, argument is designed to bring about anassent, then one might ask what kinds of assent there are, and whatvariables in an argument lead to different kinds of assent. Thisdoctrine was to replace the Alexandrian doctrine of the context theory,in which logic is taken to cover different material implementations ofsyllogistic reasoning, whether in demonstration, dialectic, rhetoric,poetics or sophistry. According to the Alexandrian version of thetheory, a stretch of discourse was to be analysed according to thecontext in which it was found: in poetry, one expected to find falseand impossible statements, in demonstration, necessary and truestatements. The Arabic logicians were to reject this version, thoughthey ultimately lost interest in the range of disciplines coordinatedby the theory.

A final factor, or range of factors, at work on the shape of thelogic treatise that emerged in the thirteenth century arose out ofdiscussions in law, especially the tradition of legal dialectic; thistradition was ultimately to crystallise as a new discipline thatreplaced the discussion of theTopics andSophisticalFallacies. Similarly disciplines grew out of grammar and theologywhich replaced the logical study of rhetoric and poetics. I examineeach of these factors in turn.

2.2.1 Logic as a Formal Science

Avicenna's doctrine of secondary intelligibles assigns logic a subjectmatter whose essential properties the logician studies; this makeslogic a science in the Aristotelian sense of the term.But—according to the strictures applying to an Aristotelianscience—no science can probe the existence of its subjectmatter, but rather must take it as given from a higher science (inthis case, metaphysics). Yet theCategories shuttles betweensecondary intelligibles and the primary intelligibles which are thepre-condition for the existence of the secondary intelligibles.

Avicenna himself adverted to the problem of whether or notCategorieswas a properly logical book, and decided that it was not, though hetreated it in theCure out of deference to Peripateticcustom. His arguments for deeming it not to be properly logical havebeen gathered together in the past (see esp. Gutas 1988: 265–267), butthe line of argument had already been stated neatly by later logicians.Here is Hillî dealing with why Tûsî moves from thefive predicables (or “five categories”) to the tencategories:

Text 12. When Tûsî finishedinvestigating the five categories which inhere in the ten categories,he began the investigation of [the ten], even though [suchinvestigation] is not part of logic. [This is] because the subjectmatter of logic is the secondary intelligibles which inhere in theprimary intelligibles. How can the primary intelligibles beinvestigated even though [such investigation] is a [presupposed] partof the science [of logic]? This would be circular. But rather, [theten categories] are investigated in logic to aid in properly realizingthe genera and specific differences. [Such investigation], then, willbe a help in discovering (istinbât) what is defined andinferred, even though it is not part of logic (HillîJawhar [1410A.H.] 23.4–8).

A study of the categories will, in short, be helpful in givingconcrete examples of the logical doctrines presented. The samearguments in removing theCategories from logic should applyto texts which investigate the commonplace reasoning oftheTopics, though I have not seen such an argument made byan Arabic logician. It is not clear to me that the argument to excludetheCategories from logic which, in Hillî's version,depends on taking secondary intelligibles to be the subject matter oflogic, still works for those who do not accept logic's subject matterto be secondary intelligibles; none the less, theCategorieswere excluded from their works too.

2.2.2 Assent and the Context Theory

Arguments aim to bring about assent; more precisely (see Text 8 above), when conceptions have been gained that produce in the mind boththe meaning of the terms in a given proposition, and the form ofcomposition of these terms, assent “occurs when there takes placein the mind a relating of this form to the things themselves asbeing in accordance with them…” In fact, different kindsof discourse can bring about one or other kind of assent, or somethingenough like assent to be included in a general theory of discourse. Igive Tûsî's statement of the Avicennan version of thecontext theory; it is the neatest statement I know ofthe criteria that divide kinds of discourse and the assents for whicheach aims.

A few preliminary words by way of introduction to this densepassage.Arabic logicians, like most Aristotelian logicians, speak of form andmatter in propositions and proofs, and they have quite specificdistinctions in mind when they do so. The matter in a proposition iswhat underwrites as true or false the modality the proposition has.When the dummy variables in a proposition are filled in with concreteterms, the resulting claim may be semantically determinate (as in“every man is an animal” and “no man is astone”), and this will make the proposition's matter eithernecessary or remote and, if necessary, make the proposition true as anecessity proposition. Alternatively, the resulting claim may besemantically indeterminate (as in “every man is writing”),and this will make the proposition's matter contingent, and theproposition true as a contingency proposition. The matter in anargument, by contrast, is the epistemic status or persuasive force eachof the premises has which, given a formally appropriate proof, willconfer asimilar or lesser epistemic status or persuasive force on theconclusion. (Note thatjâzim is rendered by Black as“apophantic” (Black 1990: 53), which I give here as“truth-apt”. For the terms of art used to deal withsyllogistic matter, see now Gutas (2012).)

Text 13. Since Avicenna had finishedexplaining the formal and quasi-formal aspects of syllogistic, heturned to its material aspects. With respect to these, syllogisticdivides into five kinds, because it either conveys an assent, or aninfluence of another kind (I mean an evoked image or wonder).What leads to assent leads either to an assent which is truth-apt or toone which is not. And what is truth-apt is either taken[in the argument] as true (haqq), or is not so taken. And whatis takenas true either is or isn't true.

That which leads to true truth-apt assent is [1] demonstration;untrue truth-apt assent is [2] sophistry. That which leads totruth-apt assent not taken as true or false but rather as [a matterof] common consent (‘umûm al-i‘tirâf)is—if it's like this—[3] dialectic (jadal),otherwise it's eristic (shaghab) which is, along withsophistry (safsata), under one kind of fallacy production(mughâlata). [And what leads] to overwhelming thoughnot truth-apt assent is [4] rhetoric; and to evocation of imagesrather than assent, [5] poetry (TûsîSharhal-Ishârât [1971] 460.1–461.12).

Tûsî immediately goes on to lay out grounds for assent topropositions, for example, because they are primary, or because theyare agreed for the purposes of discussion. Propositions to be used aspremises for demonstration make the most irresistible demands for ourassent; premises for lower kinds of discourse make weaker demands.

The vast majority of the later Arabic logicians no more than nodtowards thecontext theory in a paragraph towards the end of their treatises. Alogician should only be interested—in so far as he is interestedin material implementation of formal reasoning at all—indemonstration because it leads him to what is true and certain, and insophistry, because it may confuse him in the search for demonstrativetruth.

Philosophically, the context theory is an attempt to account forthe cognitive and communicative impact of every kind of discourse. Itexamines in extraordinary detail the Aristotelian claim that thesyllogism lies at the heart of all human reasoning and, in an attemptto make good the claim, presents an account of syllogistic formsattenuated in accordance with the epistemic matter of their premises.It also recognizes that communication depends on more than merelyobjective truth and formal validity, and offers an account of whatmotivates the assent of the human knower to any given stretch ofdiscourse. As a theory, its global reach may be more impressive thanits analytical grasp, but it is a marked advance on a theory onlypartly developed in the Alexandrian school.^[27]

2.2.3 An AlternativeOrganon?

The doctrine of secondary intelligibles cut down the number ofsubjects treated within the logic treatises, or at least, treated asstrictly logical subjects, and the doctrine of dividing knowledge intoconception and assent determined the structure of what was left inAvicennan logic treatises. Formal interests of post-Avicennan logiciansfurther limited interest in demonstration; syllogistic, for example,became a central focus of research from the thirteenth century on.Further changes were introduced for clarity of exposition.

Text 14. The later scholars came andchanged the technical terms of logic; and they appended to theinvestigation of the five universals its fruit, which is to say thediscussion of definitions and descriptions which they moved fromthePosterior Analytics; and they droppedtheCategories because a logician is only accidentally andnot essentially interested in that book; and they appended toOnInterpretation the treatment of conversion (even if it had beenin theTopics in the texts of the ancients, it is none theless in some respects among the things which follow on from thetreatment of propositions). Moreover, they treated the syllogisticwith respect to its productivity generally, not with respect to itsmatter. They dropped the investigation of [the syllogistic] withrespect to matter, which is to say, these five books:PosteriorAnalytics,Topics,Rhetoric,Poetics, andSophisticalFallacies (though sometimes some of them give a brief outline ofthem). They have ignored [these five books] as though they had neverbeen, even though they are important and relied upon in the discipline(Ibn-KhaldûnMuqaddima [1858] 112–113; cf.Ibn-Khaldûn 1958: 3, 142–143).

It is clear that whether the structure of theOrganon wasappropriate for Arabic logic treatises was contested at least untilthe end of the thirteenth century. At the same time Hillî wassetting out his logic according to the Avicennan outline oftheOrganon (see section 1.5.2 above), Shamsaddînas-Samarqandî (d. c. 1310) was writing a book laid outafter the fashion described by Ibn Khaldûn in the text above,with one major difference. Samarqandî concludedhisQistâs al-Afkâr with a long section coveringwhat he called “the etiquette of debate” and fallacies. Heconsciously adopted the etiquette of debate from treatises on forensicargument, and he told his readers that he intended it to replace studyof theTopics and theSophistical Fallacies.

Text 15. It has been the custom of ourpredecessors to place a chapter on dialectics (jadal) intheir logical works. But since the science of juristic dialectic(khilâf) of our times does not need it, I have broughtin its stead a canon for the art of disputation and its order, theproper formulation of speech [in disputation] and itsrectification. This [art] is, with respect to establishing a thesisand explaining it, just like logic with respect to deliberation andthought; for, through it we are kept on the desired path and are savedfrom the recalcitrance of speech. I have set it out in two sections,the first, on the ordering and etiquette of debate, the second, onerror and its causes.^[28]

In one sense, Samarqandî was unsuccessful: few if any laterauthors followed him in making the etiquette of debate a section oftheir logic treatises. But in another, much more significant sense,Samarqandî was entirely successful; his work by and largesupplanted theTopics andSophistical Fallacies, and gained a place in the madrasasystem along side Kâtibî'sShamsiyya; treatises on the etiquette of debate are often foundin codices along with the logic treatises.

Other language sciences also went into thecodices with the logic manuals. Of the cluster of disciplines that makeup the grammatical sciences, especially‘ilm al-wad‘(roughly, semantics) and‘ilm al-balâgha(roughly, rhetoric) compete to cover material covered by parts ofAristotelian logic. Like the logic textbooks, the textbooks for both‘ilmal-wad‘ and‘ilm al-balâgha that wereincorporated into a typical madrasa education were achieved fairly late.

‘Ilm al-wad‘ was named and consecrated as aseparate discipline by the work of the great Ash‘aritetheologian, ‘Adudaddin al-Îjî (d. 1355). InhisEpistle on Imposition Îjî drew together theviews of his predecessors on the way language came about. All agreedthat language was the result of a consciousassignation—imposition—of units of vocal sound (orexpressions,alfâz) to units of thought (ormeanings,ma‘ânî). It made no differencewhat position one adopted on the origin of language, because eitherGod or the community could function as the one imposing language. Notethat the units of thought are at least logically prior to language, solanguage is not considered a pre-condition of thought. Language is thetotality of expressions together with the totality of theirmeanings. Once expressions have been assigned their meanings by theimpositor, this is irrevocable. Having stated these common assumptionsabout language, Îjî turned to set out a typology ofimposition. Îjî noted that—in what he took to beunproblematic cases—the meaning in the mind of the one imposingthe expression is identical to the meaning it has in actual speechsituations. But what about the pronoun, “he”, which willhave a different meaning in different speech situations? This is theproblem on which Îjî dwelt in his epistle. Its solutionturned out to be, as Tashköprüzade was later to say, only adrop in the ocean of problems in‘ilm al-wad‘;once one took the notion of imposition seriously, implementing it as ageneral explanation for the relation between expression and meaningturned out to be an immense project which carried on into thetwentieth century (Weiss 1987: especially 341–345).

‘Ilm al-balâgha was standardly presented in atextbook by Khatîb Dimashq al-Qazwînî (d. 1325),The Abridgement of the Key.‘Ilmal-balâgha was a science that includes a deal of materialderiving from the work of the great eleventh-century grammarian andAsh‘arite theologian, ‘Abdalqâhiral-Jurjânî (d. 1078). Spurred by debate about how tojudge the inimitability of the Koran, Jurjânî had tried todevelop a method for evaluating rhetorical excellence.

The basictenet he wishes to emphasize from the outset is that stylisticsuperiority resides in the meanings or ideas(ma‘ânî) of words and how they areassociated with each other in a given composition (nazm), andnot in the utterances or words (alfâz) themselves.(Larkin 1982: 77)

2.3 Modal Propositions and Modal Syllogisms

There were a number of modal systems developed and debated amongthe Arabic logicians. The material devoted to the topic is toovoluminous for anything more than a sketchy account of one line ofdevelopment and debate. I follow a few aspects of Avicenna'ssyllogistic through its treatment in the thirteenth century, and itstransformation into a compact body of doctrine taught in themadrasa. With regret, in this redaction of the entry I omit mention ofAlfarabi and Averroes, not because they are not important, butbecause, first, Alfarabi's most important treatment of the syllogisticis lost and, secondly, Averroes stands outside the Avicennan traditionof logic.

It will become clear that Avicenna's syllogistic puzzled those whocame after him, and still puzzles those today who try to work out whatAvicenna was doing. There is some ground to think that Avicenna'ssyllogistic is, from a systematic point of view, something of afailure; that was a fairly common assessment among thirteenth-centurylogicians. This in turn gives rise to the thought that perhapsAvicenna wasn't trying to produce a systematic syllogistic, that hehad other goals in mind as he dealt with material descended ultimatelyfrom Aristotle'sPrior Analytics (some of it, from thecommentators, seemingly in conflict with what Aristotle is doing). IfI understand correctly, this is broadly speaking how Hodges approachesAvicenna (see Hodges 2011b, 2012a, and 2012b inOther Internet Resources).On the other hand, it may be that Avicenna has a complex system thatrepays close analysis; Thom's studies of Avicenna's syllogisticproceed on that assumption. I tend to think the Thom approach is themore promising. In any event, thirteenth-century logicians tookAvicenna to have tried and failed to present a coherent system.

In this brief overview, I describe one aspect of Avicenna'struth-conditions for modal propositions which became common doctrineamong later Arabic logicians. I go on to examine some of what Avicennasaid about the subject term of a proposition, and some of theinferences he defended. Avicenna's doctrines on both subject term andmodal inferences became much-debated issues in thirteenth-centurylogic; I follow one line of the debate.

2.3.1 Avicenna

In a famous and much-quoted passage, Avicenna lays out six conditionsunder which a proposition may be said to have a given modalization(all his examples are of necessity propositions, but the sameconditions apply to propositions under all modalizations); the firsttwo conditions are the most important:

Text 16. Necessity may be absolute(‘alâ l-itlâq), as inGod exists;[265] or it may be connected (mu‘allaqa) to a condition(shart). The condition is either [1] perpetual [relative] tothe existence of the substance [of the subject] (dhât),as inman is necessarily a rational body; by which we do notmean to say that man is and always will be a rational body, becausethis is false taken for each human individual. Rather we mean thatwhile he exists as a substance (mâ dâma mawjûdadh-dhât) as a human, he is a rational body. Likewise forevery negative which resembles this affirmative statement.

Or [the condition may be] [2] the duration (dawâm)of the subject's being described with what is set down with it, as inallmobile things are changing; this is not to be taken to mean [thisis so] absolutely, nor while the subject exists as a substance, butrather while the substance of the moving thing is moving. [266]

Distinguish between this condition and the first condition,because the first condition has set down [as the condition] theprinciple of the substance, man, whereas here the substance is setdown with a description which attaches to the substance, moving thing;the moving thing has a substance and an essence (jawhar) towhich movement and non-movement attach; but man and black are not likethat (AvicennaIshârât [1971] 264–266).

Avicenna takes a proposition under condition [1]—latertermed, for obvious reasons, thedhâtî—tobe the right proposition to use while laying out the system Aristotleshould have laid out in thePrior Analytics, and for layingout the central claims of his own metaphysics. Avicenna focussed mostof his attention on thedhâtî, and when he lookedfor the strongest converse of adhâtîproposition, he ignoredwasfî converses. Laterlogicians approached the issue ofwasfî/dhâtîconditions differently, and often foundwasfîconversesfordhâtî propositions; they had integrated thetwo readings in a way Avicenna had not.

Avicenna stipulated for the subject term of all hispropositions, whether explicitly modalized or not:

Text 17. Know that when we sayeveryJ is B, we do not mean the totality (kulliyya)ofJ is the totality ofB. Rather, we mean thatevery single thing described asJ, be it in mentalsupposition or extramental existence, be it described asJalways, or sometimes, or whatever; that thing is describedasB without further adding that it is so described at suchand such a time (waqt), or in such and such circumstances(hâl), or perpetually. All of these [modalizationswould make for a proposition] stronger than one being described asabsolute (mutlaq). So this is what is understoodfromeveryJ is B, with no addition of modal operatorsattached. On this understanding it is called a generalabsolute… (AvicennaIshârât [1971] 280 &282).

The phrase “be it in mental supposition” might be takento mean that the subject term is ampliated to the possible, so that“everyJ isB” is to be taken as“every possibleJ isB.” This is howFakhraddiin al-Râzî understood Avicenna (and two recentmodels for Avicenna's syllogistic ampliate the subject term; Thom2003, 2008b).

Avicenna gave a number of accounts of modal propositions andsyllogisms. Here, I follow a few points made in the one giveninPointers and Reminders, the cynosure of thirteenth-centurylogicians (though I also refer toSalvation which,likePointers, is available in Englishtranslation). Avicenna's syllogistic includes propositions withoutexplicit modalization (an absolute proposition, taken by Avicenna tocontain an elided temporal modality “at least once”, so thea-proposition is understood as “everyJ is at least onceB”, thee-proposition as “noJ is alwaysB”) both one- and two-sided,possibility propositions both one-sided (“everyJ is possiblyB”) andtwo-sided, and necessity propositions (“everyJ is necessarilyB”,  e-proposition “noJ is possiblyB”).

Early in his presentation, Avicenna considered whether the absolutee-proposition, “noJ isB”, converts to“noB isJ” (a conversion accepted by hispredecessors and contemporaries). Avicenna rejected absolutee-conversion and offered a counter-example found in Aristotle,“no horse is sleeping” (AvicennaNajât [1985] 39), andone of his own, “no man is laughing” (AvicennaIshârât [1971] 322). He accepted that absolute a- andi-propositions convert:

(1) “EveryJ isB” and “someJ isB” convert to “someB isJ.”

He offered an ecthetic proof for the conversion (AvicennaIshârât [1971] 330; AvicennaNajât [1985] 44). And he proved the conversion of thenecessity e-proposition:

(2) “NoJ is possiblyB” convertsto “noB is possiblyJ.”

Text 18. The universal negativenecessity proposition converts as itself, that is, as a universalnegative necessity. If necessarily noB isA, thennecessarily noA isB; were that not the case, thenpossibly a givenA isB—let that beJ, suchthat at a given moment what has become A will have becomeB, sothat it will beB andA, so that thatB is anA; this is impossible. (AvicennaNajât [1985]44–45)

Avicenna shifted on whether the necessity a- and i-propositionsconvert to absolute i-propositions (AvicennaNajât [1985] 45), or to possibility i-propositions; hislater position is that they convert as possibility i-propositions(AvicennaIshârât [1971]335–336).

(3) “EveryJ is necessarilyB”and “someJ is necessarilyB” convert to“someB is possiblyJ.”

Avicenna rejected the conversion of the possibility e-proposition(“noJ is necessarilyB”) with the samecounter-example used to reject absolute e-conversion (“no man isnecessarily laughing”). And he argued for the conversion of thepossibility a- and i-propositions as i-propositions:

(4) “EveryJ is possiblyB”and “someJ is possiblyB” convert to“someB is possiblyJ.”

Text 19. If “everyJ ispossiblyB” or “someJ is possiblyB”, then “someB is possiblyJ”(as a one-sided possibility proposition); were that not the case, thennoB is possibly J, which as you know amounts to“necessarily noB isJ”, which converts to“necessarily noJ isB”; this isabsurd. (AvicennaIshârât [1971]339ff.)

Notice that the proof for necessity e-conversion depends onpossibility i-conversion, and the proof for possibility i-conversionon necessity e-conversion. Alternative proofs could be proposed; fore-conversion, for example, one could argue that “noJ ispossiblyB” converts to “noB is possiblyJ”, if not, then “someB is possiblyJ”, but this with the first proposition produces by Ferio“someJ is not possiblyJ”, which isabsurd. This proof is open to Avicenna, given that he tookfirst-figure syllogisms with a possibility proposition as its minorpremise to be perfect, or nearly so; this syllogistic mix was rejectedby most later logicians, along with the other proofs.

2.3.2 Post-Avicennan Logicians

By and large, logicians who came after Avicenna adopted many of hisassumptions and distinctions: his understanding of the absoluteproposition (at least with respect to the modalization of itspredicate), thewasfî/dhâtîdistinction, the division of the syllogistic into repetitive andconnective. They worried, however, about a number of his claimsconcerning modal propositions and the productive syllogisms that canbe built from them. By the middle of the thirteenth century, a primaryconcern was about finding truth-conditions for propositions that couldbe useful for the sciences (see Text 24 below),though everyone started from Avicenna's formulations. A centraldistinction in these later discussions was between externalist andessentialist readings of the propositions. This is what the terms“externalist” and “essentialist” mean:

Text 20. “EveryJisB” is considered at times according to the essence(whereupon it's called “essentialist”, as though [thesubject] is an essence in a proposition used in the sciences), and atother times according to external reality (whereupon it's called“externalist”, and what is meant by “external”is what is external to the senses). (Tahtânî1948:Tahrîr 94.6–8)

Fakhraddîn al-Râzî was the first to introduce thedistinction between externalist and essentialist readings (see notesto Râzî 2002: at 400). When we say “everyJisB”,

Text 21. …we don't mean by itwhat is described asJ externally, but rather something moregeneral, which is: were it to exist externally it would be true of itthat it is J, whether it exists externally or not. For we can say“every triangle is a figure” even if there are notriangles existent externally. The meaning is rather that everythingwhich would be a triangle were it to exist would be—in so far asit existed—a figure. (RâzîMulakhkhas[2002] 141.6–10)

[…]

By the second reading, we mean by “everyJ”every single thing which exists externally among theindividualJs… On this hypothesis, were there noseptagons existent externally, it wouldn't be correct to say“every septagon is a figure”; if the only figures existentexternally were triangles, it would be correct to say “everyfigure is a triangle.” On the first reading, both of these wouldbe false. (RâzîMulakhkhas [2002]142.13–143.1)

Râzî went on to investigate inferences in bothreadings,and found the inferences from propositions with essentialist readingslined up closely with Avicenna's. The readings gave Râzîall the conversions mentioned insection 2.3.1 above except 1 (he tookthe absoluteaffirmative to convert as a possibility proposition). He also acceptedsyllogisms with possibility propositions as minor premises to beproductive. Interpretive considerations may have been at play in hisclear preference for the essentialist reading, but what explicitlymotivated the distinction is the need to have propositions refer tothings which do not exist “externally”; the examples are always ofnon-instantiated geometric figures.

Râzî was clear that he did not intend the essentialistreading to amount to an ampliation of the subject term to the possiblesuch as he attributed to Alfarabi (“Alfarabi claimed that withrespect to ‘everyJ’ one shouldn't [only] takeaccount of actually occurringJs, but everything whosedescription asJ is possible”; RâzîMulakhkhas [2002] 142.4–5). But with the phrase“were it to exist externally it would be true of it that it isJ”, Râzî posited a domain of discourseincluding non-instantiatedJs, and he seemed to take hispropositions thereby to refer to possible-Js.

That at least is how Khûnajî understoodRâzî's solution; he took it to amount to no more than anampliation of the subject term to the possible. UnlikeRâzî, Khûnajî understood the phrase“were it to exist as aJ” to include reference toimpossibleJs, and modified or rejected the conversions 1, 2, 3and 4. Before turning to how Khûnajî used theessentialist reading, consider his assessment of Râzî'sreading at the end of the chapter on conversion inDisclosure.

Text 22. Knowthat these valuations relating to conversion which we have mentioneddon't differ much from the claims of the ancients, even though theymay differ from what some recent logicians have said. Were we to besatisfied, as Alfarabi was, that for something to be a subject thepossibility [of its coming under the subject term would be enough],and not consider [the subject term's] affirmation of it in actuality,it would follow that the [universal] negative necessity propositionwould convert as a necessity proposition, affirmative possibilitypropositions would convert as a possibility proposition, theconversion of absolute propositions wouldn't result in more thanpossibility, and the syllogism in the first figure with a minorpossibility proposition would be productive, as will be clear to youafter coming to know what has gone before, and having given dueconsideration to the propositions under this technical usage. Sincethe later scholars have changed the technical usage without changingthe valuations they arrive at—such that the valuation differsaccordingly to the difference in technical usage—, they havebeen mired in nonsense. Perhaps Avicenna hesitated over the conversionof absolute propositions as either possibility or absolutepropositions just because of his hesitation over technical usage. Whenhe says that they convert as possibility propositions, he doesn'tconsider affirmation in actuality with respect to the subject; when hesays they convert as absolute propositions, he does (because the factthe absolute follows on this technical usage is just about patentlyevident, such that it wouldn't be appropriate for Avicenna to denyit). (KhûnajîKashf [2010]145.3-u)

Having rejected Râzî's understanding of theessentialist reading, Khûnajî deployed his own modifiedessentialist reading to come to different inferences. Take absolutee-conversion, which Avicenna and Râzî agreed fails(according to Râzî, it fails on either externalist oressentialist reading). Khûnajî agreed that it fails on theexternalist reading (which he took in the same way Râzîdid). Taken in Khûnajî's essentialist reading, however,“noJ is alwaysB” converts as a perpetuityo-proposition, “someB is neverJ.” To showthis is so, Khûnajî had to offer a proof for theconversion, then resist counter-examples to it. I skip the proof, andgo straight to how Khûnajî dealt with thecounter-examples.

Text 23. They argueconversion fails for these propositions because it is true, “nomoon is eclipsed”…and “no animal isbreathing”… yet [130] their converses are not true,namely, “some eclipsed is not a moon”, and “somebreathing is not animal”…

The answer to this is that we reject that “some eclipsed isnot a moon” and similar statements are false if the subject istaken according to the essentialist reading. This is because, in thiscase, its meaning is some of what would be eclipsed, were it to cometo exist, would not be a moon, insofar as it had come to exist. [Theclaim this is false] is to be rejected; the most that can be said inthis matter is that every eclipsed that has come to exist is a moon,but from this is does not follow that it is true that everything thatis eclipsed, were it to come to exist, would be a moon insofar as itcomes to exist. This is because [the proposition with an essentialistsubject] deals with actual, possible and impossible items [that comeunder the subject term]. Were we to stipulate the possibility [ofthese items] along with [the other stipulations], their status wouldbe that of externally existent things. So theeclipsed-which-is-not-a-moon, even though it is impossible, is amongthose individuals which would be eclipsed, were they to come to exist,even though it is not necessary that any would be a moon if they cameto exist.

Overall, if these propositionsare takenin the essentialist reading, the proof we have given for theirconversion works, the counter-arguments are not compelling, and theproper view must be that the conversion is correct.(KhûnajîKashf [2010] 129.14–130.12)

What this means for the counter-example considered before, “no manis always laughing”, is that it converts on this account to “somelaughing is not ever a man.” This is because we may, underKhûnajî's essentialist reading, posit the impossible“laughing-which-is-not-a-man.” With this modified essentialistreading, Khûnajî ended up with the followingconversions:

(1*)

“EveryJ is at least onceB” converts as “someB is necessarilyJ” (KhûnajîKashf [2010] 143);

(2*)

“NoJ is possiblyB”converts as “noB is everJ”(KhûnajîKashf [2010] 135);

(3*)

“EveryJ is necessarilyB”converts as “someB is necessarilyJ”(KhûnajîKashf [2010] 143);

(4*)

“EveryJ is possiblyB” hasno provable converse (KhûnajîKashf [2010]144).

The Maragha logicians—whose work included the compositionson logicmost frequently taught in the Islamic world—reflected critically onAvicenna, Râzî and Khûnajî. Everyone acceptedthat there were problems with Avicenna's inferences, but also thatKhûnajî's critique of Râzî's essentialistreading (which had saved most of Avicenna's inferences) was correct.Khûnajî's alternative development of the essentialistreading led to its own problems, however; first Abarî proved thatan e-proposition couldn't be true on Khûnajî's version ofthis reading, then Tûsî proved, nor could an a-proposition.By the time Kâtibî came to deal with the problem, he tookKhûnajî's comment inText 23 above seriously:

…the proposition with anessentialist subject] deals with actual,possible and impossible items [that come under the subject term]. Werewe to stipulate the possibility [of these items] along with [theother stipulations], their status would be that of externally existentthings.

Kâtibî further modified Khûnajî'sreading tolimit propositions with essentialist subjects to those withself-consistent subjects. In theShamsiyya,in consequence, the externalist and essentialist readings are taken tobe of the same status, which is to say, all and only the inferencesprovable in one reading are provable in the other. On the conversionsin question, Kâtibî held:

(1)	“EveryJ is at least onceB”converts as “someB is at least onceJ”;
(2*)	“NoJ is possiblyB” convertsas “noB is everJ”;
(3**)	“EveryJ is necessarilyB” converts as“someB is at least onceJwhileB”;
(4*)	“EveryJ is possiblyB” hasno provable converse.

Tahtânî, writing in the early fourteenth century,looked back over the efforts of his thirteenth-century predecessorsand summed up the nature of their inquiries. If his account iscorrect, the thirteenth-century logicians limited their investigationsto scientifically useful propositions, acknowledging at the same timethat there are many other propositions with different truth-conditionsthey could be investigating.

Text 24. It isnot to be leveled as a criticism that, because the craft should havegeneral rules, there are propositions that cannot be taken undereither of these two considerations (namely, those whose subjects areimpossible, as in “the co-creator is impossible”, and“every impossible is non-existent”). Because we say: Noone claims to limit all propositions to the essentialist and theexternalist. They do however claim that propositions used in thesciences are used for the most part under one of these twoconsiderations, so they therefore set these readings down and extracttheir qualifications so they may thereby benefit in the sciences. Thequalifications of the propositions that cannot be taken under eitherof these two considerations are not yet known; the generalization ofrules is only to the extent of human capacity. (Tahtânî1948:Tahrîr 95.pu–96.11)

Bibliography

• Abed, S., 1991,Aristotelian logic and the Arabic languagein Alfârâbî, Albany: State University of New York Press.
• Ahmed, A. Q., 2010, “Interpreting Avicenna: Urmawî/Tahtânîand the later logical tradition on propositions”,Documenti e studi sulla tradizione filosofica medievale, xxi:313–342.
• –––, 2011b, “Systematic growth insustained error: a case study in the dynamism of post-classicalIslamic scholarship”, inThe Islamic ScholarlyTradition, A. Q. Ahmed, B. Sadeghi, and M. Bonner (eds), Leiden:Brill, 343–378.
• –––, 2012, “Logic in the KhayrâbâdîSchool in India: a preliminary exploration”, inLaw andTradition in Classical Islamic Thought: Studies in Honor of ProfessorHossein Modarressi, M. Cook, N. Haider, I. Rabb, and A. Sayeed(eds), New York: Palgrave Macmillan, pp. 227–244.
• Alfarabi [al-Farabi], 1931,Ihsâ’ al-‘ulûm (Enumeration of the Sciences), Cairo: Maktabat al-Khânjî.
• –––, 1970.Kitâb al-Hurûf (Book of Letters), Muhsin Mahdi (ed.), Beirut: Dar al-Machriq.
• –––, 1986,Kitâb al-Qiyâs as-saghîr (Short Treatise on Reasoning), Beirut: Dâr al-Mashriq. Inal-Mantiq ‘inda l-Fârâbî, edited by R. al-‘Ajam, in three volumes; vol 2, pages 65–93.
• Aouad, M., 1989, “La Rhétorique. Tradition syriaque et arabe”, in Goulet (ed.) 1989–, volume 1, pp. 455–472.
• –––, 2003, “La Rhétorique: Tradition syriaque et arabe (compléments)”, in Goulet (ed.) 1989–, Supplement, pp. 219–223.
• Aristotle, 1989,Aristotle: Prior Analytics, R. Smith (ed.), Indianapolis: Hackett.
• Arnaldez, R., 1991, “Mantik”, (“logic”), inEncyclopedia of Islam, 2nd edition, Leiden: Brill, vol. 6, 442–452.
• Averroes [Ibn Rushd], 1983,Maqâlât fî al-mantiq wa-al-‘ilm at-tabî‘î, Series:Rasâ‘il falsafiyya, Casablanca: Dâr al-Nashr al-Maghribiyya. Edited by Jamâl al-Dîn ‘Alawi.
• Avicenna [Ibn Sînâ], 1952,Kitâbas-Shifâ‘: al-Madkhal, M. el-Khodeiri, G. Anawati,F. el-Ahwani (eds), Cairo: Organisation Générale desImprimeries Gouvernementales.
• –––, 1964,Kitâbas-Shifâ‘: al-Qiyâs (The Cure: Syllogism),S. Zayed and I. Madkour (eds.), Cairo: OrganisationGénérale des Imprimeries Gouvernementales.
• –––, 2005,The Metaphysics of “TheHealing” (al-Shifâ‘), Provo: BrighamYoung University. Translated M. Marmura.
• –––, 1971,al-Ishârâtwa-t-tanbîhât (Pointers and Reminders), Cairo: Daral-Marif. Edited by Sulyman Dunya, in four volumes, withTûsî's commentary at the bottom of page.
• –––, 1974, “al-Masâ‘ilal-gharîba al-‘ishrîniyya”, in Mohaghegh andIzutsu 1974: 81–103.
• –––, 1985,Kitâb al-Najât(The Salvation), Tehran: Dânishgâh-i Tihrân. Editedby Danishpazhuh.
• –––, 2011a,Avicenna's Deliverance: Logic (fromal-Najât), translated and edited by Asad Q. Ahmed, Karachi: Oxford University Press.
• Badawi, A. R., 1948/52,Mantiq Aristû, Cairo:Dâr al-Kutub al-Misriyya. 3 volumes.
• Baydâwî, 2001,The Ascending Lights (Tawali‘ al-Anwar min Matali‘ al-Anzar), translated inNature, Man and God in Medieval Islam, ed. and trans. by E. E. Calverley and J. W. Pollock, Leiden: Brill. Two volumes.
• Bertolacci, A., 2006,The Reception of Aristotle's “Metaphysics” in Avicenna's “Kitâb al-Sifâ‘”: A Milestone of Western Metaphysical Thought, Leiden: Brill.
• Black, D. L., 1990,Logic and Aristotle's “Rhetoric” and “Poetics” in medieval Arabic philosophy, Leiden: Brill.
• –––, 1991, “Aristotle's ‘Peri hermeneias’ in medieval Latin and Arabic philosophy: logic and the linguistic arts”,Canadian Journal of Philosophy, Supplementary volume 21: 25–83.
• –––, 1998, “Logic in Islamic philosophy”, inRoutledge Encyclopedia of Philosophy, London: Routledge, vol. 5, 706–713.
• Boudon, V., 2000, “Galien”, in Goulet (ed.) 1989–, volume 3, 440–466.
• Burnett, C. (ed.), 1993,Glosses and Commentaries on Aristotelian Logical Texts: The Syriac, Arabic and Medieval Latin Traditions, London: Warburg Institute.
• Calverley, E. E., 1933, “Al-Abharî‘s ‘îsâghûjî fî ‘l-mantiq’”, inThe Macdonald presentation volume: A Tribute to Duncan Black Macdonald, Princeton: Princeton University Press, 75–85.
• Danishpazhuh, M. T., 1978,al-Mantiq libni l-Muqaffa‘. Hudud al-mantiq libn Bihrîz, Tehran: Anjumân-i Shâhanshâhi Falsafah-i Iran.
• –––, 1989,al-Mantiqiyyât lil-Fârâbî, Qum: Maktabat al-Mar'ashî al-Najafî. 3 volumes.
• Dunlop, D. M., 1955, “Philosophical predecessors and contemporaries of ibn Bajjah”,Islamic Quarterly, 2: 110–116.
• Eichner, H., 2009,The Post-Avicennan Philosophical Tradition and Islamic Orthodoxy. Philosophical and Theological Summae in Context. Habilitationschrift, Martin-Luther-universität Halle-Wittenberg.
• El-Rouayheb, K., 2004, “Sunni Muslim scholars on the status of logic, 1500–1800”,Islamic Law and Society, 11(2): 213–232.
• –––, 2005, “Was there a revival of logical studies in eighteenth-century Egypt?”,Die Welt des Islams, 45(1): 1–19.
• –––, 2009, “Impossible antecedents and their consequences: some thirteenth-century Arabic discussions”,History and Philosophy of Logic, 30(3): 209–225.
• –––, 2010a. “Introduction”, in Khunaji 2010.
• –––, 2010b.Relational Syllogisms and the History of Arabic Logic, 900–1900, Leiden: Brill.
• –––, 2012, “Post-Avicennan logicians on the subject-matter of logic: some thirteenth- and fourteenth-century discussions”,Arabic Sciences and Philosophy, 22(1): 69–90.
• Elamrani-Jamal, A., 1983,Logique aristotélicienne et grammaire arabe (étude et documents), Paris: Librairie Philosophique J. Vrin.
• –––, 1989, “Alinus”, in Goulet (ed.) 1989–, volume 1, 151–152.
• –––, 1995, “Ibn Rusd et lesPremiers Analytiques d'Aristote: aperçu sur un problème de syllogistique modale”,Arabic Sciences and Philosophy, 5(1): 51–74.
• Elamrani-Jamal, A. and H. Hugonnard-Roche, 1989, “‘Les Seconds Analytiques’, tradition arabe”, in Goulet (ed.) 1989–, volume 1, pp. 521–524.
• Endress, G., 1977,The works of Yahyâ ibn ‘Adi: An analytical inventory, Wiesbaden: L. Reichert.
• –––, 1978, “Yahyâ b. ‘adi fi tabyîn al-fasl bayn al-mantiq al-falsafi wan-nahw al-‘arabî”,Journal for the History of Arabic Science, 2: 39–50.
• –––, 1986, “Grammatik und Logik. Arabische Philologie und griechische Philosophie im Widerstreit”, inSprachphilosophie in Antike und Mittelalter, B. Mojsisch (ed.), Amsterdam: Verlag B. R. Grüner, 163–299.
• –––, 2006, “Reading Avicenna in the Madrasa”, in Montgomery 2006: 371–422.
• Frank, R. M., 1990, “Review of Burkhard Mojsisch, ‘Sprachphilosophie in Antike und Mittelalter’ (Amsterdam, 1986)”,Journal of the American Oriental Society, 110(2): 356–360.
• Gätje, H., 1985, “Zur Lehre von den Voraussetzungsschlüssen bei Avicenna”,Zeitschrift für Geschichte der Arabisch-Islamischen Wissenschaften, 2: 140–240.
• Ghazâlî, 1322 AH,al-Mustasfâ min ‘ilm al-usûl (Distillation of the Principles of Jurisprudence), Bûlâq: al-Matba'a al-Amîriyya.
• –––, 1961,Mi‘yâr al-‘ilm (Yardstick of knowledge), Cairo: Dar al-ma‘arif. Edited by S. Dunya asMantiq tahâfut al-falâsifa.
• –––, 1966,Mihakk an-nazar (Touchstone for Speculation), Beirut: Dâr al-Nahda al-Hadîtha. Edited by M. Na‘sani.
• Goldziher, I., 1981, “The attitude of orthodox Islam toward the ‘ancient sciences’”, inStudies on Islam, translated and edited by M. L. Swartz, Oxford: Oxford University Press, 185–215.
• Goulet, R. (ed.), 1989–,Dictionnaire des Philosophes Antiques, Paris: Editions du Centre national de la recherche scientifique. 5 volumes so far plus a Supplement.
• Gutas, D., 2000, “Tardjama,” (“translation”, sections 2 & 3), inEncyclopedia of Islam, second edition, Leiden: Brill, vol. 10.
• –––, 1988,Avicenna and the Aristotelian tradition, Leiden: Brill.(New edition expected December 2013.)
• –––, 1993, “Aspects of literary form and genre in Arabic logical works”, in Burnett 1993: 29–76.
• –––, 1998,Greek thought, Arabic culture: The Graeco-Arabic Translation Movement in Baghdad and Early ’Abbasaid Society (2nd–4th/5th–10th c.), London and New York: Routledge.
• –––, 2002, “The Heritage of Avicenna: The Golden Age of Arabic Philosophy, 1000 – ca. 1350”, inAvicenna and His Heritage, J. Janssens and D. De Smet (eds.), Leuven: Leuven University Press, 81–97.
• –––, 2012, “The empiricism of Avicenna”,Oriens, 40(2): 391–436.
• Hasnawi, A., 2008, “Avicenna on the quantification of the predicate”, in Rahman et al. 2008: 295–328.
• –––, 2009, “Topique et syllogistique: la tradition arabe (al-Fârâbî et Averroès)”, in J. Biard and F. M. Zini (eds.),Les lieux de l'argumentation: Histoire du syllogisme topique d'Aristote à Leibniz, Turnhout, Belgium: Brepols, 191–226.
• –––, 2013, “L'âge de la démonstration. Logique, science et histoire: al-Fârâbî, Avicenne, Avempace, Averroès”, in G. Federici-Vescovini and A. Hasnawi (eds),Circolazione dei saperi nel Mediterraneo : filosofia e scienze, secoli IX–XVII, (Proceedings of the seventh colloquium of SIHSPAI held 16–18 February 2006, Florence), Florence: Edizioni Cadmo, p. 257–282.
• Hillî, 1363 SH,al-Jawhar an-nadîd fî sharh mantiq at-tajrîd (Facetted jewel on the book of abstraction), Tehran: Intishârât-Baydâr. Edited Baydârfâr.
• Hugonnard-Roche, H., 2003, “La Poétique: Tradition syriaque et arabe”, in Goulet (ed.) 1989–, Supplement, 208–218.
• –––, 1989a, “Le de interpretatione”, in Goulet (ed.) 1989–, volume 1, 513–516.
• –––, 1989b, “Les premiers analytiques”, in Goulet (ed.) 1989–2003, volume 1 516–520.
• –––, 1989c, “Les réfutations sophistiques”, in Goulet (ed.) 1989–, volume 1, 526–528.
• –––, 1989d, “L'organon: Tradition syriaque et arabe”, in Goulet (ed.) 1989–, volume 1, 502–507.
• –––, 1993, “Remarques sur la tradition arabe de l'Organon d'après le manuscrit paris, Bibliothèque nationale, ar. 2346”, in Burnett 1993, 19–28.
• Hugonnard-Roche, H. and A. Elamrani-Jamal, 1989a, “Les catègories”, in Goulet (ed.) 1989–, volume 1, 507–513.
• –––, 1989b, “Les topiques”, in Goulet (ed.) 1989–, volume 1, 524–526.
• Ibn-Khaldûn, 1858,Prolégomènes d'Ebn-Khaldoun: texte arabe (three volumes), Paris: Benjamin Duprat. Edited by M. Quatremère.
• –––, 1967,The Muqaddimah of Ibn Khaldûn, London: Routledge and Kegan Paul. 2nd edition. 3 volumes, translated by F. Rosenthal.
• Inati, S. C., 1984,Remarks and Admonitions, Part One: Logic. Toronto: Pontifical Institute of Mediaeval Studies.
• Jabre, F., 1999,al-Nass al-kâmil li-mantiq Aristû, Beirut: Dâr al-Fikr al-Lubnânî. 2 volumes.
• Kâtibî, 1948,ar-Risâla ash-Shamsiyya, Cairo: Halabî and Sons. With Tahtânî's commentary.
• Khûnajî, 2010,Kashf al-Asrâr ‘an Ghawâmid al-Afkâr (Disclosure of Secrets about the Obscurities of Thoughts). Edited K. El-Rouayheb. Tehran: Iranian Institute of Philosophy and Institute of Islamic Studies, Free University of Berlin. ISBN 978-964-8036-59-6.
• Lameer, J., 1994,Al-Fârâbî and Aristotelian syllogistics: Greek theory and Islamic practice, Leiden: Brill.
• –––, 1996, “The Organon of Aristotle in the medieval oriental and occidental traditions”,Journal of the American Oriental Society, 116(1): 90–98.
• –––, 2006,Conception and Belief in Sadr al-Din Shirazi, Tehran: Iranian Institute of Philosophy.
• Larkin, M., 1982, “Al-Jurjani's Theory of Discourse”,Alif: Journal of Comparative Poetics, 2: 76–86.
• Madelung, W., 2000. “To See all things in things in the sight of God: Nasîr al-Dîn al-Tûsî's attitude to sufism”, in N. Pourjavady and Z. Vesel 2000: 1–11.
• Mahdi, M., 1970, “Language and logic in classical Islam”, in von Grunebaum 1970: 51–83.
• Makdisi, G., 1981,The Rise of Colleges. Institutions of learning in Islam and the West, Edinburgh: Edinburgh University Press.
• Margoliouth, D. S., 1905, “The discussion between Abû Bishr Mattâ and Abû Sa‘id al-Sîrâfî on the merits of logic and grammar”,Journal of the Royal Asiatic Society, 37(1): 79–129.
• Menn, S., 2012. “Fârâbî in the reception of Avicenna's metaphysics: Averroes against Avicenna on being and unity”, in D. N. Hasse and A. Bertolacci (eds.)The Arabic, Hebrew and Latin reception of Avicenna's Metaphysics, Berlin: De Gruyter, 51–96.
• Michot, Y., 2000, “Vanités intellectuelles. l'impasse des rationalismes selon le Rejet de la Contradiction d'ibn Taymiyyah”,Oriente Moderno, 19 (n.s.): 597–617.
• Miller, L., 1984,Islamic Disputation Theory, Ph.D. thesis, Princeton.
• Mohaghegh, M. and T. Izutsu (eds.), 1974,Collected texts and papers on logic and language, Tehran: Anjomane Asar va Mafakher-e Farhangi.
• Montgomery, J. (ed.), 2006,Arabic Theology, Arabic Philosophy: From the Many to the One: Essays in Celebration of Richard M. Frank, Leuven: Peeters.
• Perler, D. and U. Rudolph (eds.), 2005,Logik und Theologie. Das “Organon” im arabischen und im lateinischen Mittelalter, Leiden: Brill.
• Peters, F. E., 1968,Aristoteles Arabus: The Oriental Translations and Commentaries of the Aristotelian Corpus, Leiden: Brill.
• Pines, S., 1996, “A parallel in the East to thelogica vetus”, in S. Stroumsa (ed.),The Collected Works of Shlomo Pines: Studies in the History of Arabic Philosophy, Jerusalem: The Hebrew University Magnes Press, vol. 3, 262–266. Originally published inPhilosophie im Mittelalter: Entwicklungslinien und Paradigmen, J. P. Beckmann (ed.), p. 125–129, Hamburg: Geburstag, 1987.
• Pococke, E. (tr.), 1663,Historia Compendiosa Dynastiarumauthore Gregorio Abul-Pharajio, Oxford.
• Pourjavady, N. and Z. Vesel, 2000,Nasîr al-Dîn Tûsî: philosophe et savant du XIII^e siècle, Bibliothèque Iranienne, 54, Leuven, Belgium: Peeters Publishers. Actes du colloque tenu à l'Université de Téhéran (6–9 Mars 1997), Tehran.
• Pourjavady, R., 2011,Philosophy in early Safavid Iran: Najm al-Dîn Mahmûd al-Nayrîzî and his writings, Leiden: Brill.
• Pourjavady, R. and S. Schmidtke, 2006,A Jewish philosopher of Baghdad: ‘Izz al-Dawla Ibn Kammûna (d. 683/1284) and his writings, Leiden: Brill.
• Rahman, S., T. Street, and H. Tahiri, 2008,The Unity of Science in the Arabic Tradition: Science, Logic, Epistemology and their Interactions, Berlin: Springer.
• Râzî, 1355 AH,Lubâb al-Ishârât (Gist of pointers), Cairo: Maktabat al-Khânjî. Edited by A. ‘Atiyya.
• –––, 1996,al-Âyât al-Bayyinât, Beirut: Dâr Sâdir. With commentary by ibn Abî l-Hadîd al-Madâ‘inî.
• –––, 2002,Mantiq al-Mulakhkhas, Tehran: Intishârât Dānišgāh-i Imām Ṣādiq. Ed. A. Karamaleki & A. Asgharinizhad.
• Rescher, N., 1963a, “al-Kindî's sketch of Aristotle's Organon”,The New Scholasticism, 37(1): 44–58. Also in Rescher 1963b: 28–38.
• –––, 1963b,Studies in the History of Arabic Logic, Pittsburgh: University of Pittsburg Press.
• –––, 1963c, “Avicenna on the logic of conditional propositions ”, in Rescher 1963b: 76–86.
• –––, 1964,The Development of Arabic Logic, Pittsburgh: University of Pittsburgh Press.
• Rudolph, U., 2005, “Die Neuberwertung der Logik durch al-Gazali”, in Perler and Rudolph 2005: 73–97.
• –––, 2012, “Al-Fârâbî: Logik,” in Rudolph & Würsch, 413–422.
• Rudolph, U., with R. Würsch, 2012,Philosophie in derislamischen Welt. vol. 1. Basel: Schwabe.
• Sabra, A. I., 1965, “Review of Nicholas Rescher'sAl-Fârâbî's Short Commentary on Aristotle's Prior Analytics (Pittsburgh 1963)”,Journal of the American Oriental Society, 85(2): 241–243.
• –––, 1980, “Avicenna on the subject matter of logic”,Journal of Philosophy, 77(11): 746–764.
• Sâwî, 1898,al-Basâ‘ir an-nasîriyya fî ‘ilm al-mantiq (Logical Insights for Nasîraddîn), Cairo: al-Matba'a al-Kubrâ. Edited by M. ‘Abduh.
• Schmidtke, S., 1991,The Theology of al-‘Allâma al-Hillî (d. 726/1325). Berlin: Klaus Schwarz.
• –––, 2013, “Two commentaries on Najm al-Dîn al-Kâtibî'sal-Shamsiyya, copied in the hand of David b. Joshua Maimonides (fl. ca. 1335–1410)”, inLaw and Tradition in Classical Islamic Thought: Studies in Honor of Professor Hossein Modarressi, M. Cook, N. Haider, I. Rabb, and A. Sayeed (eds), New York: Palgrave Macmillan, 173–191.
• Shehaby, N., 1973,Avicenna's Propositional Logic, Dordrecht and Boston: D. Reidel.
• Smyth, W., 1993, “The making of a textbook”,Studia Islamica, 78: 99–115.
• Stern, S. M., 1962, “A collection of treatises by ‘Abd al-Latif al-Baghdâdî”,Islamic Studies, 1(1): 53–70.
• Street, T., 2001, “‘The eminent later scholar’ in Avicenna'sBook of the Syllogism,”Arabic Sciences and Philosophy, 11(2): 205–218.
• –––, 2005, “Fahraddîn ar-Râzî's critique of Avicennan logic”, in Perler and Rudolph 2005: 99–116.
• –––, 2010, “Avicenna'sTwenty Questions on Logic: Preliminary Notes for Further Work”,Documenti e studi sulla tradizione filosofica medievale, 21: 97–112.
• Strobino, R., 2010, “Avicenna on the indemonstrability of definition,”Documenti e studi sulla tradizione filosofica medievale, 21: 113–163.
• –––, 2012, “Avicenna's use of the Arabic translations of thePosterior Analytics and the ancient commentary tradition”,Oriens, 40: 355–389.
• Tâhtânî, 1948,Tahrîr al-Qawâ'idal-Mantiqiyya fi sharh ar-Risâla ash-Shamsiyya, Cairo:Halabî and Sons. As lower text in Kâtibî 1948.
• Thom, P., 2003,Medieval Modal Systems: Problems and Concepts, Aldershot: Ashgate Publishing.
• –––, 2008a, “Al-Fârâbî on indefinite and privative names”,Arabic Sciences and Philosophy, 18(2): 193–209.
• –––, 2008b, “Logic and metaphysics in Avicenna's modal syllogistic”, inThe Unity of Science in the Arabic Tradition: Science, Logic, Epistemology and their Interactions, S. Rahman, T. Street, and H. Tahiri (eds), Dordrecht: Springer.
• –––, 2010, “Abharî on the logic of conjunctive terms”,Arabic Sciences and Philosophy, 20(1): 105–117.
• –––, 2012, “Syllogisms about possibility and necessity in Avicenna and Tûsî”, in C. Dutilh Novaes and O. Hjortland (eds),Insolubles and consequences: essays in honour of Stephen Read. Milton Keynes: College Publications, 239–248.
• al-Toulawy, B., 1688 [2001],Isagoge or Introduction to Logic, Beirut: NDU Press.
• Tûsî, 1971,Sharh al-Ishârât (Solution to the difficulties of pointers), Cairo: Dâr al-Ma'ârif. Published with Avicenna'sal-Ishârât.
• –––, 1974a, “Mutârahât mantiqiyya bayna l-Kâtibî wat-Tûsî”, in Mohaghegh and Izutsu 1974: 279–286.
• –––, 1974b, “Ta‘dîl al-mi‘yâr fî naqd al-asrâr” (Setting the scale for an evaluation of “Revealing Thoughts”), in Mohaghegh and Izutsu 1974: 137–248.
• von Grunebaum, G. E. (ed.), 1970,Logic in classical Islamic culture, Wiesbaden: Otto Harrassowitz.
• Walbridge, J., 2000, “Logic in the Islamic intellectual tradition: The recent centuries”,Islamic Studies, 39(1): 55–75.
• –––, 2003, “A nineteenth-century Indo-Islamic logic textbook”,Islamic Studies, 42(4): 687–693.
• Weiss, B., 1974, “Medieval Muslim discussions of the origin of language”,Zeitschrift der Deutschen Morgenlandischen Gesellschaft, 124(1): 33–41.
• –––, 1987, “‘Ilm al-wad‘: an introductory account of a later Muslim philological science”,Arabica, 34(1): 339–356.
• Wisnovsky, R., 2003,Avicenna's Metaphysics in Context, London: Duckworth Academic.
• –––, 2004, “The nature and scope of Arabic philosophical commentary in post-classical (ca. 1100–1900 AD) Islamic intellectual history: Some preliminary observations”, inPhilosophy, science and exegesis in Greek, Arabic and Latin commentaries, vol. 2, Supplement to theBulletin of the Institute of Classical Studies 83/1–2, ed. H. Baltussen et al. London, 149–191.
• Zimmermann, F. W., 1981,Al-Fârâbî's Commentary and Short Treatise on Aristotle's De Interpretatione, Oxford: Oxford University Press.

Academic Tools

	How to cite this entry.
	Preview the PDF version of this entry at theFriends of the SEP Society.
	Look up topics and thinkers related to this entry at the Internet Philosophy Ontology Project (InPhO).
	Enhanced bibliography for this entryatPhilPapers, with links to its database.

Other Internet Resources

• IslamicPhilosophy Online.
• MedievalLogic and Philosophy,maintained by Paul Vincent Spade (Indiana University)
• Max van Berchem Foundation.
• Wilfrid Hodges' papers and talk slides on Avicenna:
  • 2009, “Ibn Sînâ on analysis: 1. Proof search. Or: Abstract state machines as a tool for the history of logic”.
  • 2011a, “A note: Ibn Sînâ on the subject of logic”.
  • 2011b, “Ibn Sînâ: analysis with modal syllogisms”.
  • 2011c, “Ibn Sînâ's explanation of reductio ad absurdum”.
  • 2012a, “What would count as Ibn Sînâ having a first order logic?”.
  • 2012b, “Ibn Sînâ's modal logic”.
  SeeHodges' home page for translations of Avicenna and other papers on Arabic Logic.

Related Entries

al-Farabi |al-Ghazali |al-Kindi | al-razi | arabic-islamic-kalam |Arabic and Islamic Philosophy, disciplines in: natural philosophy and natural science |Arabic and Islamic Philosophy, historical and methodological topics in: influence of Arabic and Islamic Philosophy on Judaic thought |Arabic and Islamic Philosophy, historical and methodological topics in: influence of Arabic and Islamic Philosophy on the Latin West |Aristotle, General Topics: categories |Aristotle, General Topics: logic | categories: ancient |categories: medieval theories of |demonstration: medieval theories of |essential vs. accidental properties |Hegel, Georg Wilhelm Friedrich: dialectics | ibn-matta |Ibn Bâjja [Avempace] |Ibn Gabirol, Solomon [Avicebron] | Ibn Khaldun |Ibn Rushd [Averroes] |Ibn Sina [Avicenna] |Ibn Taymiyya |logic: modal |syllogism: medieval theories of