In philosophy, intentionality is the power of minds and mental statesto be about, to represent, or to stand for, things, properties andstates of affairs. To say of an individual’s mental states thatthey have intentionality is to say that they are mentalrepresentations or that they have contents. Furthermore, to the extentthat a speaker utters words from some natural language or drawspictures or symbols from a formal language for the purpose ofconveying to others the contents of her mental states, these artifactsused by a speaker too have contents or intentionality.‘Intentionality’ is a philosopher’s word: ever sincethe idea, if not the word itself, was introduced into philosophy byFranz Brentano in the last quarter of the nineteenth century, it hasbeen used to refer to the puzzles of representation, all of which lieat the interface between the philosophy of mind and the philosophy oflanguage. A picture of a dog, a proper name (e.g.,‘Fido’), the common noun ‘dog’ or the conceptexpressed by the word can mean, represent, or stand for, one orseveral hairy barking creatures. A complete thought, a full sentenceor a picture can stand for or describe a state of affairs. How couldsome of the represented things (e.g., dinosaurs) be arbitrarily remotein space and time from the representation (e.g., a human thought orutterance about dinosaurs tokened in 2018), while others (e.g.,numbers) may not even be in space and time at all? How could somerepresentations (e.g., direct quotations such as‘dinosaur’) even stand for themselves? How does a complexrepresentation (e.g., a complete thought or a full sentence) inheritits meaning or content from the meanings or contents of itsconstituents? How should one construe the relationship between theiconic content of pictorial representations and the conceptual contentof proposition-like representations (thoughts and utterances)? Howshould one understand the relation between the content of anindividual’s mental state and the meanings of external symbolsused by the individual to express her internal mental states? Arerepresentations of the world part of the world they represent? Do allof an individual’s mental states have intentionality or onlysome of them? The entry falls into ten sections:

• 1. Why is intentionality so-called?
• 2. Intentional inexistence
• 3. The relational nature of singular thoughts
• 4. How can distinct beliefs be about one and the same object?
• 5. True negative existential beliefs
• 6. Direct reference
• 7. Are there intentional objects?
• 8. Is intensionality a criterion of intentionality?
• 9. Can intentionality be naturalized?
• 10. Is intentionality exhibited by all mental phenomena?
• Bibliography
• Academic Tools
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• Related Entries

1. Why is intentionality so-called?

Contemporary discussions of the nature of intentionality are anintegral part of discussions of the nature of minds: what are mindsand what is it to have a mind? They arise in the context ofontological and metaphysical questions about the fundamental nature ofmental states: states such as perceiving, remembering, believing,desiring, hoping, knowing, intending, feeling, experiencing, and soon. What is it to have such mental states? How does the mental relateto the physical, i.e., how are mental states related to anindividual’s body, to states of his or her brain, to his or herbehavior and to states of affairs in the world?

Why is intentionality so-called? For reasons soon to be explained, inits philosophical usage, the meaning of the word‘intentionality’ should not be confused with the ordinarymeaning of the word ‘intention.’ As indicated by themeaning of the Latin wordtendere, which is the etymology of‘intentionality,’ the relevant idea behind intentionalityis that of mental directedness towards (or attending to) objects, asif the mind were construed as a mental bow whose arrows could beproperly aimed at different targets. In medieval logic and philosophy,the Latin wordintentio was used for what contemporaryphilosophers and logicians nowadays call a ‘concept’ or an‘intension’: something that can be both true of non-mentalthings and properties—things and properties lying outside themind—and present to the mind. On the assumption that a conceptis itself something mental, anintentio may also be true ofmental things. For example, the concept of a dog, which is afirst-levelintentio, applies to individual dogs or to theproperty of being a dog. It also falls under various higher-levelconcepts that apply to it, such as being a concept, being mental, etc.If so, then while the first-level concept is true of non-mentalthings, the higher-level concepts may be true of something mental.Notice that on this way of thinking, concepts that are true of mentalthings are presumably logically more complex than concepts that aretrue of non-mental things.

Although the meaning of the word ‘intentionality’ incontemporary philosophy is related to the meanings of such words as‘intension’ (or ‘intensionality’ with ans) and ‘intention,’ nonetheless it ought not tobe confused with either of them. On the one hand, in contemporaryEnglish, ‘intensional’ and ‘intensionality’mean ‘non-extensional’ and‘non-extensionality,’ where both extensionality andintensionality are logical features of words and sentences. Forexample, ‘creature with a heart’ and ‘creature witha kidney’ have the same extension because they are true of thesame individuals: all the creatures with a kidney are creatures with aheart. But the two expressions have different intensions because theword ‘heart’ does not have the same extension, let alonethe same meaning, as the word ‘kidney.’ On the other hand,intention and intending are specific states of mind that, unlikebeliefs, judgments, hopes, desires or fears, play a distinctive rolein the etiology of actions. By contrast, intentionality is a pervasivefeature of many different mental states: beliefs, hopes, judgments,intentions, love and hatred all exhibit intentionality. In fact,Brentano held that intentionality is the hallmark of the mental: muchof twentieth century philosophy of mind has been shaped by what, inthis entry, will be referred to as “Brentano’s thirdthesis.”

Furthermore, it is worthwhile to distinguish between levels ofintentionality. Many of an individual’s psychological stateswith intentionality (e.g., beliefs) are about (or represent)non-mental things, properties and states of affairs. Many are alsoabout another’s psychological states (e.g., another’sbeliefs). Beliefs about others’ beliefs display what is known as‘higher-order intentionality.’ Since the seminal (1978)paper by primatologists David Premack and Guy Woodruff entitled“Does the chimpanzee have a theory of mind?”, under theheading ‘theory of mind,’ much empirical research of thepast thirty years has been devoted to the psychological questionswhether non-human primates can ascribe psychological states withintentionality to others and how human children develop their capacityto ascribe to others psychological states with intentionality (cf. thecomments by philosophers Jonathan Bennett, Daniel Dennett and GilbertHarman to Premack and Woodruff’s paper and the SEP entryfolk psychology: as a theory).

The concept of intentionality has played a central role both in thetradition of analytic philosophy and in the phenomenologicaltradition. As we shall see, some philosophers go so far as claimingthat intentionality is characteristic ofall mental states.Brentano’s characterization of intentionality is quite complex.At the heart of it is Brentano’s notion of the‘intentional inexistence of an object,’ which is analyzedin the next section.

2. Intentional inexistence

Contemporary discussions of the nature of intentionality were launchedand many of them were anticipated by Franz Brentano (1874,88–89) in his book,Psychology From an EmpiricalStandpoint, from which I quote two famous paragraphs:

Every mental phenomenon is characterized by what the Scholastics ofthe Middle Ages called the intentional (or mental) inexistence of anobject, and what we might call, though not wholly unambiguously,reference to a content, direction toward an object (which is not to beunderstood here as meaning a thing), or immanent objectivity. Everymental phenomenon includes something as object within itself, althoughthey do not do so in the same way. In presentation, something ispresented, in judgment something is affirmed or denied, in love loved,in hate hated, in desire desired and so on.

This intentional inexistence is characteristic exclusively of mentalphenomena. No physical phenomenon exhibits anything like it. We can,therefore, define mental phenomena by saying that they are thosephenomena which contain an object intentionally within themselves.

As one reads these lines, numerous questions arise: what does Brentanomean when he says that the object towards which the mind directsitself ‘is not to be understood as meaning a thing’? Whatcan it be for a phenomenon (mental or otherwise) to exhibit ‘theintentional inexistence of an object’? What is it for aphenomenon to ‘include something as object within itself’?Do ‘reference to a content’ and ‘direction toward anobject’ express two distinct ideas? Or are they two distinctways of expressing one and the same idea? If intentionality can relatea mind to something that either does not exist or exists wholly withinthe mind, what sort of relation can it be?

Replete as they are with complex, abstract and controversial ideas,these two short paragraphs have set the agenda for all subsequentphilosophical discussions of intentionality in the late nineteenth andthe twentieth century. There has been some discussion over the meaningof Brentano’s expression ‘intentional inexistence.’Did Brentano mean that the objects onto which the mind is directed areinternal to the mind itself (in-exist in the mind)?Or did he mean that the mind can be directed ontonon-existent objects? Or did he mean both? (See Crane, 1998for further discussion.)

Some of the leading ideas of the phenomenological tradition can betraced back to this issue. Following the lead of Edmund Husserl (1900,1913), who was both the founder of phenomenology and a student ofBrentano’s, the point of the phenomenological analysis has beento show that the essential property of intentionality of beingdirected onto something isnot contingent upon whether somereal physical target exists independently of the intentional actitself. To achieve this goal, two concepts have been central toHusserl’s internalist interpretation of intentionality: theconcept of anoema (pluralnoemata) and the conceptofepoche (i.e., bracketing) or phenomenological reduction.By the word ‘noema,’ Husserl refers to the internalstructure of mental acts. The phenomenological reduction is meant tohelp get at the essence of mental acts by suspending all naivepresuppositions about the difference between real and fictitiousentities (on these complex phenomenological concepts, see the papersby Føllesdal and others conveniently gathered in Dreyfus(1982). For further discussion, see Bell (1990) and Dummett(1993).

In the two paragraphs quoted above, Brentano sketches an entireresearch programme based on three distinct theses. According to thefirst thesis, it is constitutive of the phenomenon of intentionality,as it is exhibited by mental states such as loving, hating, desiring,believing, judging, perceiving, hoping and many others, that thesemental states are directed towards things different from themselves.According to the second thesis, it is characteristic of the objectstowards which the mind is directed by virtue of intentionality thatthey have the property which Brentano calls intentional inexistence.According to the third thesis, intentionality is the mark of themental: all and only mental states exhibit intentionality.

Unlike Brentano’s third thesis, Brentano’s first twotheses can hardly be divorced from each other. The first thesis caneasily be recast so as to be unacceptable unless the second thesis isaccepted. Suppose that it is constitutive of the nature ofintentionality that one could not exemplify such mental states asloving, hating, desiring, believing, judging, perceiving, hoping, andso on, unless there wassomething to be loved, hated,desired, believed, judged, perceived, hoped, and so on. If so, then itfollows from the very nature of intentionality (as described by thefirst thesis) that nothing could exhibit intentionality unless therewereobjects—intentional objects—that satisfiedthe property Brentano called intentional inexistence.

Now, the full acceptance of Brentano’s first two theses raises afundamental ontological question in philosophical logic. The questionis: are there such intentional objects? Does due recognition ofintentionality force us to postulate the ontological category ofintentional objects? This question has given rise to a major divisionwithin analytic philosophy. The prevailing (or orthodox) response hasbeen a resounding ‘No.’ But an important minority ofphilosophers, whom I shall call ‘the intentional-object’theorists, have argued for a positive response to the question. Sinceintentional objects need not exist, according to intentional-objecttheorists, there are things that do not exist. According to theircritics, there are no such things.

We shall directly examine the intentional-object theorists approach insection 7. Before doing so, in section 3, we shall examine the waysingular thoughts about concrete particulars in space and time can beand have been construed as paradigms of genuine intentional relations.On this relational construal, an individual’s ordinary singularthought about a concrete physical particular involves a genuinerelation between the individual’s mind and the concrete physicalparticular. In sections 4–5, we shall examine two puzzles thatfurther arise on the orthodox paradigm. First, we shall deal with thepuzzle of how a rational person can believe of an object referred toby one singular term that it instantiates a property andsimultaneously disbelieve of the same object referred to by a distinctsingular term that it instantiates the same property. Section 4 isdevoted to Frege’s solution to this puzzle. In section 5, weshall scrutinize Russell’s solution to the puzzle of truenegative existential statements. In section 6, we shall see how thetheory of direct reference emerged within the orthodox paradigm out ofa critique of both Frege’s notion of sense and Russell’sassumption that most proper names in natural languages are disguiseddefinite descriptions.

3. The relational nature of singular thoughts

Many non-intentional relations hold of concrete particulars in spaceand time. If and when they do, their relata cannot fail to exist. IfCleopatra kisses Caesar, then both Cleopatra and Caesar must exist.Not so with intentional relations. If Cleopatra loves Caesar, thenpresumably there is some concrete particular in space and time whomCleopatra loves. But one may also love Anna Karenina (not a concreteparticular in space and time, but a fictitious character). Similarly,the relata of the admiration relation (another intentional relation)are not limited to concrete particulars in space and time. One mayadmire not only Albert Einstein but also Sherlock Holmes (a fictitiouscharacter). As the following passage from the Appendix to the 1911edition of his 1874 book testifies, this asymmetry betweennon-intentional and intentional relations puzzled Brentano:

What is characteristic of every mental activity is, as I believe Ihave shown, the reference to something as an object. In this respect,every mental activity seems to be something relational. […] Inother relations both terms—both the fundament and theterminus—are real, but here only the first term—thefundament is real. […] If I take something relative […]something larger or smaller for example, then, if the larger thingexists, the smaller one exists too. […] Something like what istrue of relations of similarity and difference holds true forrelations of cause and effect. For there to be such a relation, boththe thing that causes and the thing that is caused must exist.[…] It is entirely different with mental reference. If someonethinks of something, the one who is thinking must certainly exist, butthe object of his thinking need not exist at all. In fact, if he isdenying something, the existence of the object is precisely what isexcluded whenever his denial is correct. So the only thing which isrequired by mental reference is the person thinking. The terminus ofthe so-called relation does not need to exist in reality at all. Forthis reason, one could doubt whether we really are dealing withsomething relational here, and not, rather, with something somewhatsimilar to something relational in a certain respect, which might,therefore, better be called “quasi-relational.”

While the orthodox paradigm is clearly consistent with the possibilitythat general thoughts may involve abstract objects (e.g., numbers) andabstract properties and relations, none of which are in space andtime, special problems arise with respect to singular thoughtsconstrued as intentional relations to non-existent or fictitiousobjects. Two related assumptions lie at the core of the orthodoxparadigm. One is the assumption that the mystery of the intentionalrelation should be elucidated against the background ofnon-intentional relations. The other is the assumption thatintentional relations which seem to involve non-existent (e.g.,fictitious) entities should be clarified by reference to intentionalrelations involving particulars existing in space and time.

The paradigm of the intentional relation that satisfies the orthodoxpicture is the intentionality of what can be calledsingularthoughts, namely those true thoughts that are directed towardsconcrete individuals or particulars that exist in space and time. Asingular thought is such that it would not be available—it couldnot be entertained—unless the concrete individual that is thetarget of the thought existed. Unlike the propositional contents ofgeneral thoughts that involve only abstract universals suchas properties and/or relations, the propositional content of asingular thought may involve in addition a relation to a concreteindividual or particular. The contrast between ‘singular’and ‘general’ propositions has been much emphasized byKaplan (1978, 1989). In a slightly different perspective, Tyler Burge(1977) has characterized singular thoughts as incompletelyconceptualized orde re thoughts whose relation to theobjects they are about is supplied by the context. On some views, theobject of the singular thought is evenpart of it. On theorthodox view, part of the importance of true singular thoughts for aclarification of intentionality lies in the fact that some truesingular thoughts are about concrete perceptible objects. Singularthoughts about concrete perceptible objects may seem simpler and moreprimitive than either general ones or thoughts about abstractentities.

Consider, for example, what must be the case for belief-ascription (1)to be true:

1. Ava believes that Lionel Jospin is a Socialist.

Intuitively, the belief ascribed to Ava by (1) has intentionality inthe sense that it isof orabout Lionel Jospin andthe property of being a Socialist. Besides being a belief (i.e., aspecialattitude different from a wish, a desire, a fear oran intention), the identity of Ava’s belief depends on itspropositional content. What Ava believes is identified by the embedded‘that’-clause that can stand all by itself as in (2):

2. Lionel Jospin is a Socialist.

On the face of it, an utterance of (2) is true if and only if a givenconcrete individual does exemplify the property of being a Socialist.Arguably, it is essential to the proposition that Avabelieves—the proposition expressed by an utterance of(2)—that it is about Jospin and the property of being aSocialist. Just by virtue of having such a true belief, Ava musttherefore stand in relation—the belief relation—to Jospinand the property of being a Socialist. Notice that Ava can have abelief about Jospin and the property of being a Socialist even thoughshe has never seen Jospin in person.

From within the orthodox paradigm, one central piece of the mystery ofintentionality can be brought out by reflection on the conditions inwhich simple singular thoughts about concrete individuals are true.This is the problem of therelational nature of the contentsof true singular beliefs. In order to generate this problem, it is notnecessary to ascend to false or abstract beliefs about fictionalentities. It is enough to consider how a true thought about a concreteindividual that exists in space and time can arise. On the one hand,Ava’s belief seems to be a singular belief about a concreteindividual. It seems essential to Ava’s belief that it has thepropositional content that it has. And it seems essential to thepropositional content of Ava’s belief that Ava must stand inrelation to somebody else who can be very remote from her in eitherspace or time. On the other hand, Ava’s belief is a stateinternal to Ava. As John Perry (1994, 187) puts it, beliefs and otherso-called ‘propositional attitudes’ seem to be“local mental phenomena.” How can it be essential to aninternal state of Ava’s that Ava stands in relation to someoneelse? How can one reconcile the local and the relational characters ofpropositional attitudes?

4. How can distinct beliefs be about one and the same object?

The problem of the relational nature of the contents of true singularthoughts can be made more acute by the following puzzle that exercisedGottlob Frege (1892): how can one rationally holdtwodistinct singular beliefs that are both about one and the same object?As we shall see momentarily, this puzzle is related to a secondpuzzle: the puzzle of how a statement expressing a belief aboutidentity can both be true and informative. If the belief relation is agenuine relation, then it would seem that it is likekicking:if Jacques Chirac kicked Lionel Jospin and if Lionel Jospin was theFrench Prime minister in 2001, then Jacques Chirac kicked the FrenchPrime minister in 2001. Not so with belief, as we shall seemomentarily. Notice that in ordinary contexts, the word‘belief’ can be used to denote either a person’sstate or the content of that state.

Ever since Frege, it has been standard practice in analytic philosophyto investigate the intentional structure of much human thought byinquiring into the logical structure of the language used by speakersto express it or to ascribe it to others. (See, e.g., Dummett (1973)for a forceful justification.) Suppose that Ava correctly believesthat Hesperus is shining as a result of seeing that Hesperus shines.Suppose also that she fails to believe that Phosphorus is shiningbecause, although she correctly believes that Hesperus is called‘Hesperus,’ she incorrectly believes that‘Phosphorus’ is the name of a different planet (that sheis not currently seeing) and she fails to know that‘Phosphorus’ is in fact another name for Hesperus. Sowhereas the first belief report is true, the second belief report isfalse:

3. Ava believes that Hesperus is shining.
4. Ava believes that Phosphorus is shining.

Given that ‘Hesperus’ and ‘Phosphorus’ arejust names of the same object, how can Ava believe one thing anddisbelieve the other? Given that ‘Hesperus’ and‘Phosphorus’ apply to the same object, it would seem that‘Hesperus is shining’ is true if and only if‘Phosphorus is shining’ is true and that these twosentences express one and the same proposition. If what is essentialto the proposition that Ava believes is that it is about Hesperus andthe property of shining, how can she believe one thing and fail tobelieve the other since both are about Hesperus?

Another related puzzle is the puzzle of how identity statements canboth be true and informative. It seems clear that Ava could not doubtthat ‘Hesperus is Hesperus’ expresses a truth. But itseems clear that she can—in fact she does—doubt that‘Hesperus is Phosphorus’ expresses a truth. In fact, whenshe learns that ‘Hesperus is Phosphorus’ does express atruth, she is surprised. How can it be? (See Richard 1990 and Salmon1986.)

Frege (1892) offered a very influential solution to both puzzles. Thiscommon solution is based on his famous distinction between thereference (orBedeutung) and thesense (orSinn) of an English proper name. The sense, which is the modeof presentation of the reference, is presumably something abstractthat can both be instantiated by a concrete individual and present to,or grasped by, a mind. This distinction is in some ways reminiscent ofthe distinction between extension and intension and is inconsistentwith John Stuart Mill’s (1884) view that proper names have adenotation and no connotation.

The reason (3) and (4) can, on Frege’s view, have differenttruth-values is that the embedded sentences or‘that’-clauses in (3) and (4)—namely (5) and(6)—donot express one and the same proposition. Theyexpress different propositions (or thoughts). Frege uses the GermanGedanke for ‘thought.’

5. Hesperus is shining.
6. Phosphorus is shining.

How can (5) and (6) express different propositions? Unlikenon-ordinary contexts such as (3) and (4), in which they are part ofan embedded ‘that’-clause, in ordinary contexts such as(5) and (6), ‘Hesperus’ and ‘Phosphorus’ havethe sameBedeutung (or reference). But they have differentsenses (Sinn) or different modes of presentation of theircommon reference. On the Fregean view, what is essential to thethought or proposition expressed by an utterance of a sentencecontaining a singular term is itssense, not its reference.Propositions have senses, not individuals, as constituents. Ava lacksa piece of knowledge. But given that ignorance is not irrationality,Ava can rationally believe that Hesperus is shining and fail tobelieve that Phosphorus is shining. Similarly, a statement expressinga belief about identity can both be true and informative because thetwo singular terms that flank the identity sign in an identitystatement have both a sense and a reference. The identity statement istrue because they have the same reference. It is informative becausethey have different senses or they present their common reference viadifferent modes of presentation.

On the Fregean view, in (3) and (4), ‘Hesperus’ and‘Phosphorus’ do not have their ordinary reference (orBedeutung), namely the planet to which they both apply: theyhave an ‘oblique’ reference. In (3), the oblique referenceof ‘Hesperus’ is its ordinary sense. In (4), the obliquereference of ‘Phosphorus’ is its ordinary sense. And wealready agreed that ‘Hesperus’ and‘Phosphorus’ in (5) and (6) have different ordinarysenses. So in (3), ‘Hesperus’ has an ‘oblique’or ‘indirect’ sense, which is the mode of presentation ofthe ordinary sense ‘Hesperus’ has in (5). Similarly, in(4) ‘Phosphorus’ has an ‘oblique’ sense, whichis the mode of presentation of the ordinary sense‘Phosphorus’ has in (5). On the Fregean view, a thought orbelief can beabout a concrete individual (its reference),but what matters to the individuation (or the identity) of thethought’s content is not the reference of the singular term, butthe sense or mode of presentation of the reference, i.e., somethingabstract. For further discussion, see the entry onGottlob Frege.

5. True negative existential beliefs

When Brentano reflected on the “quasi-relational” natureof the intentionality of thoughts about things that neednotexist, he wrote that if one “is denying something, the existenceof the object is precisely what is excluded whenever [one’s]denial is correct”. He thus assumed that one can correctly andcoherently deny the existence of things that do not exist. To showthat one can do so, however, is no easy task. The version of thepuzzle that exercised both Alexius Meinong (a disciple ofBrentano’s) and Bertrand Russell at the turn of the twentiethcentury is the puzzle of true negative existential beliefs. How can aperson correctly believe that Pegasus does not exist? For a person tocorrectly believe that Pegasus does not exist, she must have a beliefwhose content is the same as the content expressed by a true utteranceof sentence (7).

7. Pegasus does not exist.

How can the proposition expressed by an utterance of (7) be both trueand about Pegasus? The puzzle arises from the observation that if theproposition is true, then presumably it is not about Pegasus since itsays that Pegasus does not exist. Conversely, if it is about Pegasus,then Pegasus must exist. But if so, then it cannot be true since itdenies the existence of Pegasus. Thus, the puzzle has the form of adilemma: either the proposition expressed by (7) is false or it is notabout Pegasus. At least, the puzzle is generated by the pair ofassumptions that ‘Pegasus’ is a proper name and thatproper namesmust have a reference. Is the first assumptionright?

In his 1905 paper, “On denoting,” Russell embraced theview that neither ‘Pegasus’ nor in fact most proper namesof natural languages are genuine ‘logical’ proper names.He held the epistemological view that unless one is directlyacquainted with something, one cannot use in thought orlanguage a genuine ‘logical’ proper name referring to it.Nor can one entertain a genuine singular thought about it. If one isnot directly acquainted with an object, then one must instead form ageneral thought that is not about any particular individual. In fact,Russell (1911, 1919) held a dual view of acquaintance: on the onehand, he thought that acquaintance is a relation that can only holdbetween someone’s mind and his or her own sense data. On theother hand, he held the view that one can be acquainted withuniversals (such as e.g., colors). If most—if notall—names of natural languages are not genuine‘logical’ names, then what are they and what is theirfunction in human thought and communication? On Russell’s view,they are “disguised” or abbreviated definite descriptions,i.e., they are short for some definite description. Their logicalfunction is that of a definite description.

On the face of it, the grammatical form of the quasi-English sentence‘the F is G’ indicates that it serves to express asubject-predicate (or singular) proposition true if and only if theobject that exemplifies the property expressed by predicate‘F’ also exemplifies the property expressed by predicate‘G’. But Russell (1905) designed a method—his famoustheory of definite descriptions—for eliminating the Englishdefinite article ‘the’ (as in ‘the F’) bymeans of a logical formula of first-order logic involving onlyquantifiers and variables. On his analysis, ‘the F is G’can be paraphrased into the general existentially quantifiedproposition (8):

8. ∃x[Fx &∀y(Fy →y=x) &Gx]

(8) is true if and only if there is one and only one individual thatisF andG. This proposition will be false just incase nothing or more than one thing is bothF andG.

Combined with the assumption that ‘Pegasus’ is not a namebut a disguised definite description—that it is short for e.g.,‘the winged horse’—Russell’s theory ofdefinite descriptions thus leads to a solution to the puzzle of truenegative existential beliefs. The solution is to accept the secondhorn of the dilemma: the proposition is not about Pegasus. On thisaccount, one can correctly believe that Pegasus does not exist, sincewhat one believes is what is expressed by an utterance of (7), namelythe true proposition that there does not exist a unique individualthat is a winged horse. Clearly, Russell’s solution to thepuzzle of true negative existential beliefs shows how, inBrentano’s own terms, “if someone thinks of something, theone who is thinking must certainly exist, but the object of histhinking need not exist at all” and furthermore the thought maybe true. For further discussion, see the entry onBertrand Russell.

6. Direct reference

Within the orthodox paradigm in the philosophy of mind and language ofthe 1960’s and 1970’s, there was an important swing of thependulum away from the implications of Frege’s and especiallyRussell’s doctrines for intentionality. The so-called“theory of direct reference” has contributed torehabilitate the view that concrete individuals matter more to theidentity of the singular thoughts that humans entertain than theFrege/Russell doctrines allow. According to Frege’s distinctionbetween sense and reference, what matters to the identity of a thoughtabout a concrete individual is not the individual thought about butthe abstract sense by means of which he is thought about. According toRussell, most thoughts that seem prima facie to be about concreteindividuals are in fact not singular thoughts but generally quantifiedpropositions. Much of the impetus for the theory of direct referencecame from the implications of the semantics of modal logic for theintentionality of singular thoughts and beliefs.

Saul Kripke (1972) noticed an important difference between thebehavior of a proper name and the behavior of a coreferential definitedescription expressing a contingent or non-essential property of itsreferent, in modal contexts. Consider two sentences (9) and (10), eachcontaining some modal operator like ‘might’ (thatexpresses a possibility) and such that the former contains a propername while the latter contains a coreferential definitedescription:

9. Jacques Chirac might have been a Socialist.
10. The president of France elected in 2002 might have a been aSocialist.

The definite description ‘the president of France elected in2002’ happens to be true of Jacques Chirac of whom it expressesa contingent property. There certainly exists a metaphysicallypossible world in which either Chirac was not a candidate in the 2002French presidential elections or he was a candidate but he lost theelection.

An utterance of (9) asserts that there exists a possible world inwhich Jacques Chirac is a member of the Socialist party, which he infact is not. Given the deep connection between the speech act ofassertion and speaker’s belief, an utterance of (9) expressesthe counterfactual belief about Chirac that he could have been aSocialist. Unlike an utterance of (9), an utterance of (10) isambiguous. On one reading, it has the same truth-conditions as does anutterance of (9) and it serves to express the same belief.Alternatively, an utterance of (10) says of someone who is in fact aSocialist, and who therefore is not Chirac, that he could have beenelected president in 2002.

Thus, the following contrast emerges. An utterance of (9) can onlyserve to express a counterfactual belief or thought about Chirac,i.e., the belief ascribing to Chirac the counterfactual property ofbeing a Socialist. An utterance of (10) can serve to express the samebelief about Chirac. But it can also serve to express an entirelydifferent counterfactual belief about a different individual, who as amatter of fact happens to be a Socialist. This differentcounterfactual belief would be true e.g., in a possible world in whichJospin (who is a Socialist) won the 2002 presidential elections.

On the basis of the fact that, unlike (9), (10) can serve to expresstwo distinct counterfactual beliefs, Kripke (1972) hypothesizes that aproper name is what he calls arigid designator.‘Jacques Chirac’ in (9) is rigid for in all possibleworlds it refers to one and the same concrete individual, i.e., theindividual to whom it in fact refers in the actual world. By contrast,the definite description ‘the president of France elected in2002’, which happens to express a contingent property of Chirac,is not a rigid designator because it does not pick one and the sameindividual in all possible worlds. When evaluated with respect todifferent worlds, it is true of different individuals. Of course, somedefinite descriptions (e.g., ‘the square root of 21’) doexpress essential properties of what they are true of (in this case, anumber). According to Kripke (1980), unlike proper names, whoserigidity isde jure, definite descriptions expressingessential properties of an object are rigidde facto. Forfurther discussion, see the entry onreference.

Arguably, the goal of the theory of direct reference is to emphasizethe depth of the gap between the intentionality of singular thoughtsand the intentionality of general thoughts. Concrete individuals arenot constituents of the contents of the latter. But they areconstituents of the contents of the former. Three arguments have beenbuttressed to dismantle the Russellian disdain for the peculiarintentionality of singular thoughts expressible by proper names: amodal argument, an epistemological argument and what can be called a“transcendental” argument.

According to the modal argument, if the proper name‘Cicero’ were just short for some definite description,e.g., ‘the Roman orator who denounced Catiline,’ then itwould follow that the sentence ‘Cicero is the Roman orator whodenounced Catiline’ would express anecessary truth,i.e., a proposition true in all possible worlds. But this seemsabsurd: there certainly is a possible world in which Cicero did notdenounce Catiline.

According to the epistemological argument, from the same assumption,it follows that the sentence ‘Cicero is the Roman orator whodenounced Catiline’ expresses a proposition knowableapriori, so that it makes no sense to imagine that historians maydiscover by empirical research that in fact somebody else denouncedCatiline or that nobody did. But this too seems absurd.

Finally, according to the transcendental argument, people use propernames in thought and in verbal communication to track, pick out andexchange valuable information about concrete particulars. Althoughthey may lack information expressible by some definitedescription—let alone by a single definite description—foruniquely identifying many concrete particulars, still people manage tosecure reference to them. Furthermore, as a person comes to learn moreand more information about an object or a person, she comes toassociate different definite descriptions to the referent of a propername. If follows that no one definite description seems suitable tocapture the content of a proper name.

According to the theory of direct reference, the function of suchlinguistic devices as proper names, indexicals and demonstratives isto introduce a concrete individual or particular into the propositionand/or belief expressed. To use David Kaplan’s (1979, 387)revealing word, a concrete individual is “trapped” withina singular proposition. The theory of direct reference seems like auseful antidote against the Frege/Russell tendency to minimize thecontribution of concrete particulars to the individuation of humansingular thoughts. Three trends of thoughts in recent philosophy ofmind and language have built on the theory of direct reference. First,many of the insights of the theory of direct reference have beenextended from thoughts about concrete individuals to thoughts aboutnatural kinds by Kripke (1972) and Putnam (1974). This extension playsa crucial role in the externalist view of intentional mental states(about which seesection 10). Secondly, neo-Fregeans have responded to the challenge of the theoryof direct reference by providing a suitable notion of“object-dependent” or “de re” sense(see Evans, 1982 and McDowell, 1984). (For a response to Frege’spuzzle about how two distinct beliefs can be about the same object onbehalf of the theory of direct reference, see Salmon, 1986). Thirdly,the metaphysical and epistemological underpinnings of singularthoughts (and singular propositions) have given rise to a richdiscussion of the contrast between two broad perspectives:descriptivism and singularism. According to descriptivism, we can onlythink about objects by thinking about the properties which theyinstantiate. But according to singularism, not all thoughts aboutobjects are mediated by thoughts about their properties. For furtherdiscussion, see the papers collected in Jeshion (ed.) (2010), inparticular Recanati (2010).

7. Are there intentional objects?

Sections 4, 5 and 6 described three moves made within the orthodoxparadigm in analytic philosophy in response to puzzles raised by theintentionality of singular thoughts about concrete particulars. Inparticular, the dispute between the theory of direct reference andeither the Fregean distinction between sense and reference or theRussellian assumption that ordinary proper names are disguiseddefinite descriptions can be seen as internal to the orthodox paradigmaccording to which there are only existing objects, i.e., concreteparticulars in space and time. Brentano, however, sketched thepossibility of an alternative paradigm based on the acceptance of theview that intentional objects may be non-existent objects or abstractobjects. (For a general survey of the role of Brentano in theemergence of the non-orthodox theory of intentional objects inAustrian philosophy, see Smith, 1994.)

To see how the theory of intentional objects flows fromBrentano’s characterization of intentionality, recall (fromsection 2) that it follows from the nature of intentionality (asdescribed by Brentano’s first thesis) that nothing could exhibitintentionality unless there were objects – intentional objects– that satisfied the property Brentano called “intentionalinexistence.” Consider the following inference schema licensedby the rule of existential generalization and instantiated by thenon-intentional relation expressed by the English verb“kiss” in (11):

11a. Cleopatra kissed Caesar.
11b. Cleopatra kissed something.

If (11a) is true, so is (11b). The question is: is this validinference schema also instantiated by the following pairs (12)-(15)involving intentional relations?

12a. Cleopatra loved Caesar.
12b. Cleopatra loved something.

13a. The Ancient Greeks worshiped Zeus.
13b. The Ancient Greeks worshiped something.

14a. Ponce de Leon searched for the fountain of youth.
14b. Ponce de Leon searched for something.

15a. Modern criminologists admire Sherlock Holmes.
15b. Modern criminologists admire something.

On the one hand, unlike (11), (12)-(15) involve intentional relations.On the other hand, unlike the intentional relation in (12), theintentional relations in (13)-(15) seem to involve particulars whichdon’t exist (or haven’t existed) in space and time.Intentional-object theorists hold that the above inferences involvingboth non-intentional and intentional relations constitute data thatcall for a consistent explanation. In other words, theintentional-object theorist accepts, whereas his critic rejects, thevalidity of the rule of existential generalization for bothintentional and non-intentional relations, whether the relata of theintentional relations are concrete particulars in space and time ornot. On the non-orthodox assumption that the inference schemainstantiated by (11) can be instantiated by (12)-(15) as well, then inlogical notation, the second coordinate of every pair (11)-(15) shouldbe symbolized thus:

11c. ∃x(Cleopatra kissedx)
12c. ∃x(Cleopatra lovedx)
13c. ∃x(Ancient Greeks worshipedx)
14c. ∃x(Ponce de Leon searched forx)
15c. ∃x(Modern criminologists admirex)

Thus, the issue between the intentional-object theorist and his criticis whether the variable bound by the standard existential quantifierof first-order logic should range not merely over concrete particularsexisting in space and time but also over all sorts of other entitiesas well. Note that the issue is orthogonal to the contrast between theobjectual and the substitutional interpretation of the existentialquantifier since the dispute over the admission of intentional objectsis wholly internal to the objectual interpretation of the quantifier.The question that arises for the intentional-object theorist is: whatis the best theory of the objects over which (13c)-(15c) seem toquantify?

Meinong (1904) supposed that objects like Zeus, the fountain of youth,Sherlock Holmes, etc., are non-existent objects which exemplify theproperties attributed to them. On his view, the fountain of youth isan object that instantiates both the property of being a fountain andthat of having waters which confer everlasting life. But it fails toinstantiate the property of existence. Meinong seemed to suppose thatfor any group of properties, there is an object which instantiatesthose properties. Some of the resulting objects exist and others donot. Russell (1905) found this view of intentional objectsontologically unacceptable since it involves the acceptance ofentities such as golden mountains (which are inconsistent withphysical and chemical laws) and round squares (which are inconsistentwith the laws of geometry). His theory of definite descriptions wasprecisely designed to avoid these ontological consequences (seesection 5). However, by clarifying distinctions proposed by bothMeinong and his student Ernst Mally, Parsons (1980) has recentlyoffered a theory of non-existent objects, which is based on theassumption that existence is a special kind of property. This theoryuses a quantifier “∃”, which does not implyexistence. To assert existence, he uses the predicate“E!”. Thus, the assertion that there arenon-existent objects can be represented in Parsons’ theorywithout contradiction by the logical formula“∃x(~E!x).” Furthermore, Parsonsdistinguishes between “nuclear” and“extranuclear” properties. Only the former, which areordinary, non-intentional kinds of properties, contribute toindividuating objects. The set of extranuclear properties involveintentional properties, modal properties and existence. Armed withthis distinction among properties, Parsons (1980) has been able toavoid Russell’s objections to Meinong’s naive theory ofintentional objects. (For further details, see Parsons, 1980.) Anoriginal account of the possibility of entertaining true thoughtsabout non-existent objects, based on the contrast between pleonastic(or representation-dependent) and non-pleonastic (natural orsubstantial) properties, has been developed by Crane (2013).

The theory of intentional objects has also been developed in aslightly different way. Meinong’s student Ernst Mally (1912)proposed that fictional and mythical objects, as well as objects likeround squares, do not instantiate the properties attributed to thembut “have” those properties in a different way. For Mally,the fountain of youth is “determined” by the properties ofbeing a fountain and having waters which confer everlasting life, butthis object doesn’t instantiate those properties in thetraditional sense. Given Mally’s distinction, the fact thatthere is an object which is determined by the properties of beinggolden and of being a mountain does not contradict the contingent factthat nothing instantiates these two properties, nor does Mally have tothink of intentional objects as non-existent. Rather, he treats themas existing abstract objects. Thus, whereas Parsons uses two kinds ofproperties to develop a theory of non-existent objects, a neo-Mallyansuch as Zalta (1988) uses two kinds of predication –exemplification (which corresponds to instantiation) and encoding(which corresponds to Mally’s notion of determination) –to develop a theory of abstract objects. These abstract objects arepart of the explanations of both the truths expressed by (13a)-(15a)and the validity of the inferences in (13a,b)-(15a,b). As such,abstract objects may well exist. Nonetheless, some abstract objects(e.g., Sherlock Holmes and Zeus) may be said “not toexist” in the sense that nothing exemplifies the propertieswhich they encode.

Though Quine’s (1948) well-known paper “On what thereis,” raises serious ontological questions for intentional-objecttheories, both Parsons and Zalta have provided answers toQuine’s queries, in their respective work. Nonetheless, to thisday, many contemporary philosophers have been reluctant to embraceintentional-object theories for two related reasons. First of all,they have been eager to avoid what they see as the heavy ontologicalcommitments incurred by intentional-object theories. Secondly, theontology of non-existent and abstract objects has seemed difficult tosquare with the ontology of the contemporary natural sciencesaccording to which the world contains only concrete objects that existin space and time. (See Section 9 for further discussion.)

The theory of intentional objects, however, may derive support fromthe following, arguably counterintuitive, consequences ofFrege’s and Russell’s views, respectively. Frege’stheory faces two problems. First (13a)-(15a) would appear to expresstruths. But on Frege’s view, they lack a truth-value, since theyinvolve singular terms devoid of reference and, according to Frege, ifpart of a sentence lacks a reference, then the sentence itself failsto have a truth-value (see section 4). Secondly, the inferences in(13)-(15) appear to be valid. But on Frege’s view, one cannotvalidly infer (13b) from (13a) if (13a) has no truth-value. Similarlyfor the other pair of sentences (14) and (15). Russell’s viewfaces two analogous problems. First, as noted above, (13a)-(15a)appear to be true. But on Russell’s analysis, proper names suchas “Zeus” in (13a) and “Sherlock Holmes” in(15a) are abbreviated definite descriptions and, given his analysis ofdefinite descriptions, both (13a) and (15a) turn out to express falseexistentially quantified propositions (see section 5). Secondly, if(13a)-(15a) are indeed false, as Russell’s view would have it,then one cannot validly infer (13b)-(15b), respectively, from theircorresponding premisses. For a recent novel account of the distinctionbetween true and false thoughts about non-existent objects, cf. Crane(2013) and for further discussion of the general topic of existence,see the SEP entry on existence.

8. Is intensionality a criterion of intentionality?

Within the orthodox paradigm, an entirely different reaction to thepuzzles of intentional inexistence has been to try to clarify theontological difficulties by ascending to a higher semantic level thatcan, as Willard Van Orman Quine (1960, 272) says, “carry thediscussion into a domain where both parties are better agreed on theobjects (viz., words).” Semantic ascent allows one to rise fromtalk about things to talk about talk about things, i.e., words. Incontemporary analytic philosophy, Roderick Chisholm (1957, 298) wasthe first to contemplate the formulation of “a working criterionby means of which we can distinguish sentences that are intentional,or are used intentionally, in a certain language from sentences thatare not.” The idea is to examine sentences that reportintentionality rather than intentionality itself.

Intensionality (with ans) is non-extensionality. Twofeatures are characteristic of extensionality. First, if a linguisticcontext is extensional, two coreferential terms can be substituted onefor the othersalva veritate as illustrated by (16) and(17):

16. Hesperus shines.
17. Phosphorus shines.

If (16) is true, so is (17). Secondly, the law of existentialgeneralization applies to either (16) or (17) to yield‘∃x(x shines).’ Not so withintensionality. As illustrated by examples (3) and (4) repeated here,the truth of (3) does not always entail the truth of (4):

3. Ava believes that Hesperus is shining.
4. Ava believes that Phosphorus is shining.

Nor can existential generalization always be validly applied tosentences reporting beliefs, since from the fact that John believesthat angels have wings, it does not follow that there are things suchthat John believes of them that they have wings.

Chisholm’s criterion of intensionality is threefold. First, asentence reports an intentional phenomenon if it contains a singularterm that purports to refer to some object and it is such that neitherit nor its negation implies that the purported reference of thesingular term does or does not exist. The first criterion amounts tothe recognition that if a sentence containing a singular term reportsan intentional phenomenon, then it fails to satisfy the law ofexistential generalization (from ‘Fa’ infer‘∃xFx’). Secondly, a true sentence reportsan intentional phenomenon if it contains a singular term‘a’ and if replacement of‘a’ by coreferential term‘b’ results in transforming the true sentenceinto a false sentence that differs only from the former in that‘b’ replaces ‘a’. The secondcriterion amounts to recognition that if a sentence containing asingular term reports an intentional phenomenon, then it fails thetest of the substitutivity of coreferential termssalvaveritate. Finally, if a complex sentence containing an embedded‘that’-clause reports an intentional phenomenon, thenneither it nor its negation entail the truth of the propositionexpressed by the embedded ‘that’-clause.

Chisholm (1957) argued that reports or descriptions of intentional orpsychological phenomena cannot be reduced to (or eliminated in favorof) descriptions of behavior. The intensionality or non-extensionalityof reports of intentionality was taken to show that descriptions andexplanations of psychological phenomena cannot be described norexplained in terms of a vocabulary describing non-intentionalphenomena. As Quine (1960, 220) put it, “there is no breakingout of the intentional vocabulary by explaining its members in otherterms”. Chisholm (1957) took this conclusion to show thecorrectness of Brentano’s third thesis that intentionalityis the mark of the mental.

The question can be decomposed into two questions. On the one hand,acceptance of intensionality as the criterion of intentionality seemsto reflect the endorsement of a general linguistic view ofintentionality in the following sense: what matters to the mental(i.e. non-linguistic) state reported are the properties of thelinguistic report. There are at least two reasons for scepticism aboutthe linguistic view of intentionality. On the other hand, there aresome specific reasons for questioning two of Chisholm’scriteria. I start with the latter. It seems hard to deny that statesofknowledge are states with intentionality. At least,reports of knowledge states satisfy Chisholm’s secondnon-substitutivity criterion. From the fact that knowledge ascription(18) is true, it does not follow that (19) is, even though‘Cicero’ and ‘Tully’ are coreferential:

18. Tom knows that Cicero denounced Catiline.
19. Tom knows that Tully denounced Catiline.
20. Cicero denounced Catiline.

However, unlike belief reports, reports of knowledge arefactive: (18) could not be true unless (20) was true andCicero did in fact denounce Catiline. Thus, unlike belief reports,reports of knowledge fail Chisholm’s third criterion. Given that(20) is extensional, it obeys the law of existential generalization.If the truth of (20) follows from the truth of (18) and if (20)satisfies the law of existential generalization, then so does (18). Ifso, then knowledge reports also fail to satisfy Chisholm’s firstcriterion.

One way to deal with this objection might be to argue that knowledgereports fail the test of existential generalization precisely because,unlike belief states, states of knowledge fail to exhibitBrentano’s intentional inexistence: only beliefs, not states ofknowledge, can be directed towards states of affairs that fail toobtain and towards non-existent entities. Alternatively, one mightmake a distinction between states with a stronger and states with aweaker intentionality. Reports of the former (like beliefs) satisfyChisholm’s three criteria. Reports of the latter (like states ofknowledge) only fail the substitutivity test.

The problem with this strategy is that there are sentences that seemto describe intentional relations and that, unlike knowledge reports,arenot intensional at all, for they pass the substitutivitytest. This is the case of sentences about what Fred Dretske (1969)callsnonepistemic perception. If, when he was alive, someonesaw the French writer Romain Gary, then sheipso facto sawAjar, for Ajar was no other than Romain Gary. However, if she failedto know that ‘Ajar’ was another name for Romain Gary,while seeing Romain Gary, she may have failed to seethat theman in front of her was Ajar. A fortiori, in this nonepistemic sense,one cannot see an individual unless there is an individual to be seen.One possible response might be to bite the bullet and deny thatnonepistemic perception is an intentional state at all. If so, then,as Zalta (1988, 13) notes, linguistic reports of intentional phenomenado satisfy at least one of Chisholm’s criteria ofintensionality.

If seeing is intentional, then not all reports of intentionality areintensional. That not all reports of intentionality are intensional isa problem for the linguistic view according to which intensionality isthe criterion of intentionality. A second problem is thatintensionality is also a feature of sentences that are about phenomenaother than intentionality. Sentences that involve or are aboutmodalities such as necessity, about natural laws, about causation allexhibit intensionality. So, for example, the truth of (21) does notentail the truth of (22) even though everything that happens toexemplify propertyQ happens to exemplify propertyR:

21. It is a natural law that allPs areQ.
22. It is a natural law that allPs areR.

But necessity, natural laws or causation do not, on the face of it,exhibit what Brentano took to be the defining characteristics ofintentionality. So it seems as if the intensionality of the report ofa phenomenon is neither necessary nor sufficient for theintentionality of the reported phenomenon. Arguably, ‘P’,‘Q’ and ‘R’ in (21)-(22) are not singularterms at all. If they are treated as such, then, even though they maybe true of the same set of individuals, they do not refer or expressone and the same property. Still, the point illustrated by nomicity isthat the intensionality of a linguistic report is not sufficient forthe intentionality of the reported phenomenon.

9. Can intentionality be naturalized?

As we saw in section 8, Quine (1960, 220), a leading critic ofintentional objects (in the sense of section 7), agrees with Chisholm(1957) that the intentional vocabulary cannot be reduced to somenon-intentional vocabulary. Chisholm (1957) took this conclusion toshow the correctness of Brentano’s third thesis thatintentionalityis the mark of the mental. From the sameconclusion, Quine (1960, 221) presented an influential dilemma withboth epistemological and ontological implications. The first horn ofthe dilemma is to accept the “indispensability of intentionalidioms and the importance of an autonomous science of intention”and to reject a physicalist ontology. The second horn of the samedilemma is to accept physicalism and renounce the“baselessness” of the intentional idioms and the“emptiness” of a science of intention. This dilemma hasbeen influential in contemporary philosophy of mind.

The common legacy of Chisholm (1957) and Quine (1960) is thelinguistic view of intentionality (accepted by e.g., Dennett 1969).Whether intensionality is indeed the defining criterion ofintentionality, one can certainly question Brentano’s thesisthatonly mental phenomena exhibit intentionality by noticingthat some non-mental things exhibit something very much likeBrentano’s intentional inexistence, namely sentences of naturallanguages. Sentences of natural languages have meaning and by virtueof having meaning, they can be, just like states of mind, directedtowards things other than themselves, some of which need not exist inspace and time. Sentences of natural languages, however, arenon-mental things.

One influential response to this objection to this part ofBrentano’s third thesis has been to grant a second-rate, i.e., adegraded and dependent, intentional status to sentences (see Haugeland1981, Searle 1980, 1983, 1992, Fodor 1987). On this view, sentences ofnatural languages have no intrinsic meaning of and by themselves. Nordo utterances of sentences have an intrinsic content. Sentences ofnatural languages would fail to have any meaning unless it wasconferred to them by people who use them to express their thoughts andcommunicate them to others. Utterances borrow whatever‘derived’ intentionality they have from the‘original’ (or ‘primitive’) intentionality ofhuman beings with minds that use them for their purposes (see Dennett1987 for dissent). If, as Jerry Fodor (1975, 1987, 1994, 1998, 2008)has argued, there exists a “language of thought”consisting of mental symbols with syntactic and semantic properties,then possibly the semantic properties of mental symbols are theprimary bearers of ‘original’ intentionality. (See theentry on thelanguage of thought hypothesis.)

So the question is: does any non-mental thing exhibit‘original’ intentionality? The question is made morepressing by Quine’s dilemma, according to which one must choosebetween Brentano’s third thesis and a physicalist ontology.So-called ‘eliminative materialists’ (see Churchland 1989)resolutely opt for the second horn of Quine’s dilemma and denypurely and simply the reality of human beliefs and desires. As aconsequence of their denial of the reality of beliefs and desires, theeliminative materialists must face the challenge raised by theexistence of physical objects whose existence depends on theintentions, beliefs and desires of their designers, i.e., humanartifacts. Others, like Daniel Dennett (1971, 1978, 1987, 2017), whorejects any sharp distinction between original and derivedintentionality on the grounds that original intentionality itself isthe output of natural selection, take a so-called‘instrumentalist’ position. On Dennett’s view, theintentional idiom fails to describe or explain any real phenomenon.However, in the absence of detailed knowledge of the physical lawsthat govern the behavior of a physical system, the intentional idiom(the ‘intentional stance’ as Dennett calls it) is a usefulstance for predicting a system’s behavior. Among philosophersattracted to a physicalist ontology, few have accepted the outrighteliminativist materialist denial of the reality of beliefs anddesires. Nor have many of them found it easy to answer the puzzlingquestion raised by the instrumentalist position: how can theintentional idiom make useful predictions if it fails to describe andexplain anything real?

A significant number of physicalist philosophers subscribe to the taskof reconciling the existence of intentionality with a physicalistontology (for a forceful exposition see Field 1978, 78–79). Onthe assumption that intentionality is central to the mental, the taskis to show, in Dennett’s (1969, 21) terms, that there isnot an “unbridgeable gulf between the mental and thephysical” or that one can subscribe to both physicalism andintentional realism. Because intentional states areof orabout things other than themselves, for a state to haveintentionality is for it to have semantic properties. As Jerry Fodor(1984) put it, the naturalistic worry of intentional realists who arephysicalists is that “the semantic proves permanentlyrecalcitrant to integration to the natural order”. Given that ona physicalist ontology, intentionality or semantic properties cannotbe “fundamental features of the world,” the task is toshow “how an entirely physical system could nevertheless exhibitintentional states” (Fodor, 1987). As Dretske (1981) puts it,the task is to show how to “bake a mental cake using onlyphysical yeast and flour”. Notice that Brentano’s own viewthat ‘no physical phenomenon manifests’ intentionality issimply unacceptable to a physicalist. If physicalism is true, thensome physical things are also mental things. The question for aphysicalist is: does any non-mental thing manifest intentionality?

Clearly, one way to relieve the tension between physicalism andintentional realism is to argue that intentionality can be, and infact is, exhibited by non-mental things. There have been severalproposals in analytic philosophy in the past twenty years to suggestways of accomplishing this program, which has been called ‘thenaturalization of intentionality.’ The common strategy is toshow that Brentano was wrong in claiming that only mental things canexhibit intentionality. This strategy is related to the assumptionthat intentional relations whose relata are concrete particularsshould have primacy over intentional relations whose relata are not(seesection 7). I shall illustrate two distinct proposals for implementing thiscommon goal.

One influential strategy for showing that non-mental things canexhibit intentionality has been Fred Dretske’s (1980, 1981,1994)information-theoretic proposal that a device thatcarries information does exhibit some degree of intentionality. Theview is an extension of Paul Grice’s (1957) notion ofnatural meaning: unlike the English word ‘fire,’which non-naturally means fire, smoke naturally means fire. The word‘fire’ can be tokened in the absence of any fire eitherfor the purpose of expressing a thought about what to do if there wasone or perhaps to mislead somebody else into falsely thinking thatthere is one. But there cannot be any smoke unless there is a fire. Aswe shall see momentarily, it is a feature of both the originalintentionality of beliefs and the derived intentionality of utterancesthat they can be misrepresentations.

In essence, the information-theoretic proposal is that deviceS carries information about instantiations of propertyG if and only ifS’s beingF isnomically correlated with instantiations ofG. IfSwould not beF unless propertyG were instantiated,thenS’s beingF carries information about, oras Dretske likes to say, indicatesG-ness. A fingerprintcarries information about the identity of the human being whose fingerwas imprinted. Spots on a human face carry information about adisease. The height of the column of mercury in a thermometer carriesinformation about the temperature. A gas-gauge on the dashboard of acar carries information about the amount of fuel in the car tank. Theposition of a needle in a galvanometer carries information about theflow of electric current. A compass carries information about thelocation of the North pole. In all such cases, a property of aphysical device nomically covaries with some physical propertyinstantiated in its environment (for critical discussion of theinformational program, see Kistler 2000, Loewer 1987, 1998 and Putnam1986).

Now, insofar as it is not alaw that polar bears live at theNorth pole, even though they happen to live there, a compass will failto carry information about where polar bears happen to live in spiteof the fact that it does carry information about the North pole. Ifso, then reports of what a compass indicates exhibit one ofChisholm’s features of intensionality, namely coextensive termsare not freely substitutablesalva veritate in such reports.By contrast, if it is law that variations of temperature covary withvariations in atmospheric pressure, then by virtue of indicating thetemperature, the height of the column of mercury in a thermometer willalso indicate atmospheric pressure. If there is a law relating currentflow to voltage differences, then by indicating the former, agalvanometer will indicate the latter. One can, however, believe andeven know that there is a current flow between two points withoutbelieving, let alone knowing, that there is a voltage differencebetween the two points, if one fails to know that it is a law that ifthere is flow of electric current between two points, then there is avoltage difference between these two points (see Jacob 1997 fordiscussion).

So although reports of the information carried by such physicaldevices exhibit some of the intensionality exhibited by reports ofintentional mental states, the intensionality exhibited by the latteris clearly stronger than the intensionality exhibited by the former.On the one hand, it is difficult to generate the strong intentionalityof mental states from the information-theoretic account of the weakintentionality of non-mental things. On the other hand, given that theinformation relation is the converse of a nomic correlation, it isdifficult for informational semantics to account for misrepresentationas well as for the normativity of the contents of mental states. Seethe entry oncausal theories of mental content..

A second influential proposal for dealing with the difficulties leftpending by the information-theoretic approach and for showing thatsome non-mental things can exhibit intentionality has been RuthMillikan’s (1984, 1993, 2000, 2004)teleosemanticapproach. Millikan’s teleosemantic approach rests on two basicassumptions, the first of which is that (unlike a natural sign) anintentional representation is a relatum in a three-place relationinvolving two mechanisms: a producer of the representation and aconsumer, both of which are cooperative devices whose activities arebeneficial to both. Millikan’s second assumption is thatBrentano’s relation of intentional inexistence is exhibited bybiological functions. Given any sort of biological purpose or design,it might fail to be fulfilled. For example, if it is the function orpurpose of a mammal’s heart to pump blood, then a mammal’sheart ought to pump blood even though it might fail to do so. Notice,however, that whereas biological organs have functions that may failto be fulfilled, they do notipso facto exhibitintentionality in Brentano’s full sense: neither a heart nor astomach areof orabout anything. Millikan’sclaim, however, is not that having a function is sufficient foraboutness, but that it is necessary. Arguably, a device cannot beabout or represent anything unless it can misrepresent what it isabout. Presumably, for a device to misrepresent what it is about isfor it to misfunction. But unless the device had some function, itcould simply not misfunction. If this is correct, then nothing couldbe a representational system—nothing could have content orintentionality—unless it had what Millikan (1984) calls a‘proper’ function.

The relevant notion of a function here is the biological teleological,not the dispositional one: the function of an organ is not what theorgan is disposed to do, but what it was selected to do (see Millikan1984 and Neander 1995). Arguably, nothing can have a function unlessit results from some historical process of selection or other.Selection processes are design processes. Most advocates ofteleosemantics accept the etiological account of functions accordingto which the function of a device is a selected effect, i.e. an effectproduced by the device that explains the continued proliferation oftokens of this type of device. Thus, according to“teleosemantic” theories, design is the main source offunction, which in turn is the source of content or intentionality.Such theories are called “teleosemantic” theories invirtue of the connection between design or teleology and content. Onecontentious issue is whether the teleological approach championed byMillikan can be combined with informational semantics so thatS can be said to represent instances of propertyFif and only if it isS’s function to carry informationaboutF. On the one hand, against this proposal, Millikan(2004) has argued that the information carried by a sign depends onits causes, not its effects: according to teleosemantics and theetiological approach to functions, the function of a device is one ofits effects: it does not depend on its causes. On the other hand,Millikan (2017) proposes to redefine the border between concepts andpercepts by deepening her semiotic approach to perception based on therelated twin notions ofunicepts andunitrackers.Neander (2017) and Shea (2018) have further explored the possibilityof combining informational semantics and a teleological approach. Forfurther discussion of teleosemantics, see the SEP entry onteleological theories of mental content and the papers collected inRyder, Kinsbury and Williford (eds.)(2011).

Now, selection processes can be intentional or non-intentional.Artifacts (including words and other symbols of natural languages)derive their functions from some intentional process. Whilepsychological mechanisms (e.g., belief-forming mechanisms) derivetheir proper functions from anon-intentional selectionprocess, particular belief states have derived proper functions. Theparadigmatic non-intentional process is the process of naturalselection by which Charles Darwin explained the phylogenetic evolutionof biological species: natural selection sorts organisms that survive.But no intentional agent is responsible for the sorting. Millikan(1984, 2004, 2005) has also extended her teleosemantic approach to thecontents of intentional conventional signs (i.e. linguistic symbols).If this sort of teleosemantic proposal could be fully worked out, thenit would kill two birds with one stone. On the one hand, it wouldpoint a way in which the intentionality of minds derives from theintentionality of biological things (see Rowlands 1999 fordiscussion). On the other hand, it would show that some of thenormativity of mental states is already exhibited by biologicalfunctions (see Neander, 1995). Both questions are currently topics ofmuch discussion in the philosophy of mind. Many philosophers such asDavidson (1980), Kripke (1982), McDowell (1994) and Putnam (1988,1994), for example, have either expressed serious reservations aboutthe program or provided reasons for scepticism. For furtherdiscussion, see the essays in MacDonald and Papineau (eds.) 2006, andalso the entries onteleological theories of mental content andteleological notions in biology. Subsequently Burge (2010) criticized attempts to naturalizeintentionality by appeal to the notion of biological function on thegrounds that it is, according to him, a deep mistake to identifyrepresentational success (truth or accuracy) with fulfillment ofbiological function and representational failure (falsity orinaccuracy) with failure of biological function. Unlikerepresentational (or semantic) success or failure, fulfillment orfailure of a biological function is, according to Burge, practicalsuccess or failure.

10. Is intentionality exhibited by all mental phenomena?

Perceptions, beliefs, desires and intentions and many other“propositional attitudes” are mental states withintentionality. They are about or represent objects and states ofaffairs under a particular psychological mode or format. Perceptions,beliefs, desires and intentions illustrate a basic duality of theintentionality of the mental: the duality between mind-to-world andworld-to-mind directions of fit. In order to clarify this duality,Elizabeth Anscombe (1957, 56) considers a mere “shoppinglist”. The list may either be used as a set of instructions (ora blueprint) for action by a customer in a store or it can be used asan inventory by a detective whose purpose is to draw a record of whatthe customer is buying. In the former case, the list is not to berevised in the light of what lies in the customer’s grocery bag.But in the latter case, it is. If a mismatch should occur between thecontent of the grocery bag and the list used by the customer, then theblame should be put on the customer, not on the list. In the case of amismatch between the content of the bag and the list drawn by thedetective, the detective should correct his list.

Building on Anscombe’s insight, Searle (1983) argues that thereare two opposite “directions of fit” that either speechacts or mental states can exemplify: just as the speech act ofassertion has a word-to-world direction of fit, beliefs andperceptions have a mind-to-world direction of fit. It is the functionof an assertion to state a fact or an actual state of affairs.Similarly, it is the function of a belief and a perception to match afact. Unlike assertions, orders have a world-to-word direction of fit.Unlike beliefs and perceptions, desires and intentions have aworld-to-mind direction of fit. It is the function of an order torepresent a non-actual possible or impossible state of affairs.Similarly, it is the function of a desire and an intention torepresent a non-actual possible or impossible state of affairs.

Now the following questions arise: are Brentano and thephenomenological tradition right? Do all mental states exhibitintentionality? Is intentionality a feature of every aspect of humanexperience? Are all forms of consciousness consciousnessofsomething? Does every mental state possess one or the other directionof fit? Do sensations (e.g., pains), feelings, emotions (e.g.,depression) all exhibit intentionality? These questions are verycontroversial in contemporary philosophy of mind. Before examiningvarious contradictory answers to these questions, a preliminaryquestion is relevant. Whether Brentano was right or not, why should wewant a mark or a criterion of the mental at all?

The question of why we should seek a criterion of the mental at allhas been made pressing by some recent remarks of the linguist NoamChomsky (2000, 75, 106), according to whom methodological naturalismmandates that we use terms like ‘mind’ and‘mental’ on a par with terms like ‘chemical’,‘optical’ or ‘electrical.’ Since we do notseek to determine the true criterion of the electrical or the mark ofthe chemical, by naturalistic parity of reasoning, Chomsky argues, weshould no more seek a criterion of the mental. Whether we needcriteria respectively for the chemical and for the optical, it is agenuine issue whether the English word ‘mental’ canjustifiably apply to things as diverse as e.g., a pain and the beliefthat 5 is a prime number. As Richard Rorty (1979, 22) has put it,“the attempt to hitch pains and beliefs together seems adhoc—they don’t seem to have anything in common except ourrefusal to call them ‘physical’”. His conclusion isthat the word ‘mental’ expresses no single property, letalone a ‘natural kind.’ On Rorty’s irrealist view,the word ‘mental’ is just part of an academiclanguage-game with no scientific explanatory import.

Thus, Rorty’s radical irrealist picture of the mind relies onthe observation that pains and arithmetical beliefs seem to havenothing in common. Not many contemporary philosophers of mind wouldaccept Rorty’s irrealist picture of the mind. But most dorecognize that if minds are real, thentwo problems arise:the problem of intentionality and the problem of consciousness orconscious phenomenal experience. Most would claim that a solution tothe problem of intentionality is notipso facto a solution tothe problem of consciousness. Why is that so?

Human beings can experience the world in various ways by means ofseveral distinct sensory modalities (vision, audition, touch,olfaction). They are also aware of parts of their bodies as when theysuffer pains. The problem of consciousness is often called “theproblem ofqualia” because states with a strongphenomenal character—like pains, visual or olfactorysensations—are states that introspectively seem endowed with astrong intrinsic subjective quality. The general problem ofconsciousness is to explain, in Thomas Nagel’s (1974) famousphrase, “what it is like” to be a certain creature with aphenomenal experience. What is the phenomenal character—thephenomenology—of the various forms of human experience? Few ifany philosophers—physicalist or otherwise—are inclined toassume that, unlike intentionality, phenomenal consciousness can beexemplified by non-mental things. Not many would deny that, althoughpains, visual sensations, olfactory sensations, auditive sensationsare very different experiences, nonetheless they all exhibit a commonproperty called “phenomenal consciousness”. From both ascientific and a physicalist perspective, the questions arise whetherphenomenal consciousness is physical and whether it can be explainedin physical terms, i.e., as a result of processes happening in thebrain.

As many philosophers are willing to recognize, the concept expressedby the word ‘consciousness’ is much in need ofclarification. Three such clarifications are worth mentioning. Two ofthem consist in a pair of distinctions drawn by David Rosenthal(1986). One distinction is between creature consciousness and stateconsciousness. The other distinction is between transitive andintransitive consciousness. A creature can be said to be‘intransitively’ conscious if she is alive and normallyresponsive to ongoing stimuli. She stops being intransitivelyconscious while in a dreamless sleep, if she is knocked out, druggedor comatose. A creature can be said to be ‘transitively’conscious if she is consciousof things, properties andrelations in her environment. Whereas a creature can be bothintransitively conscious and transitively conscious of something, amental state can only be intransitively conscious. One importantaspect of the problem of consciousness is the problem of how to drawthe line between conscious and unconscious mental states. A thirdclarification has been Ned Block’s (1995) distinction betweenaccess consciousness (or A-consciousness) and phenomenal consciousness(or P-consciousness). Whereas a state is said to be A-conscious if itis poised for free use in reasoning and for direct rational control ofaction and speech (i.e. available or accessible to several cognitivemechanisms), the P-consciousness of a state is what it is like to bein that state (whether or not it has A-consciousness). In recent work,Block (2007) has argued that much evidence from the cognitivescientific investigation of the visual system corroborates hisdistinction between P- and A-consciousness. For example, on hisinterpretation, experiments on change blindness and also theneuropsychological investigation of brain-lesioned human patients withneglect show that attention and working memory are necessary parts ofA-consciousness, but not of P-consciousness. What makes a stateA-conscious is that its content is made available to various cognitivesystems (e.g., attention and memory). Furthermore, not unless a visualstimulus is attended and stored in working memory can an individualreport having seen it. But Block (2007) takes the evidence to showthat an individual can be P-conscious of the content of anunreportable stimulus, i.e. a stimulus whose content has not beeneither attended or stored in working memory. For supporting arguments,see Dretske (2004, 2007). Block’s interpretation of thecognitive scientific data has been criticized by scientific advocatesof the so-called “global neuronal workspace model” ofconsciousness: see e.g., Dehaene et al. (2006) and Naccache andDehaene (2007), which is a commentary to Block (2007). The globalneuronal workspace model of consciousness nicely fits withDennett’s (1991, 2005) position on intentionality andconsciousness (which he has himself dubbed the “fame (in thebrain) theory of consciousness.” (For further discussion ofthese issues, see the SEP entry onattention.)

On the one hand, the notion of transitive creature consciousness seemslike a close cousin to the notion of intentionality. On the otherhand, what makes a person’s mental state A-conscious is that theperson may have access to it. Presumably, a person may have consciousaccess to one of her A-conscious mental states in virtue of havingsome other mental state (e.g., a thought or belief) directed to it. Sohaving states with intentionality seems like a condition for anymental state to be A-conscious. It follows that if the problem ofconsciousness is to be clearly distinguished from the problem ofintentionality, the key question is that of explaining how a mentalstate can be P-conscious.

Many philosophers do not accept Brentano’s third thesis thatintentionality is the mark of all mental states. They do not rejectBrentano’s second thesis on the grounds that intentionality canbe exhibited by some non-mental things. They reject it because, likeBlock (1996) and Peacocke (1983), they subscribe to a view that can becalled ‘anti-intentionalism,’ according to which aperson’s conscious mental state has a phenomenal character thatcannot be accounted either by its own intentionality (if it has any)or by the intentionality of some other of his or her mental states.Nor do they embrace Rorty’s irrealist attitude towards themental. Some of the philosophers, who fall under the label‘anti-intentionalism,’ may accept the thesis thatintentionality and the mental happen to coincide. But since they claimthat intentionality in turn derives from phenomenal consciousness,they are not quite faithful to the spirit of Brentano’s thesisthat intentionality is the constitutive feature of the mental.

The anti-intentionalists, who reject both Rorty’s irrealism andBrentano’s thesis that intentionality is the true mark of themental, can be divided into two groups. Some, like Ned Block (1995,1996), would accept adual view according to which mentalstates fall into a division between intentional states and phenomenalstates. As we shall see momentarily, this division is denied by theintentionalists. In between the intentionalists and the phenomenalrealists, who accept the dual view, lies the intermediate view ofphilosophers such as Colin McGinn (1989), Sydney Shoemaker (1996) andCharles Siewert (1998), who see an intimate connection betweenintentional and phenomenal states.

Other anti-intentionalists, like John Searle (1990, 1992) and GalenStrawson (1994), go one step further and reject both Brentano’sthesis and the dual view of the mind. They hold consciousness to bethe true criterion of the mental. Arguably, as noted above, they mightaccept the thesis that intentionality coincides with the mental, butthey hold the view that intentionality derives from consciousness. Onthe one hand, Strawson (1994) clearly holds phenomenal consciousnessto be the true criterion of the mental. On the other hand, Searle(1992) embraces what he calls “the Connection principle,”according to which unless a mental state is available toconsciousness, it does not qualify as genuinely mental. As a result,Searle (1992) seems to endorse the view that availability toconsciousness is the criterion of the mental. Now, the view thatavailability to consciousness is the true criterion of the mentalentails that states and processes that are investigated by cognitivescience and that are unavailable to consciousness will fail to qualifyas genuine mental states. This view has been vigorously disputed byChomsky (2000). On the natural assumption that beliefs areparadigmatic mental states, the view that phenomenal consciousness isthe true criterion of the mental further entails that there issomething it is like to have such a propositional attitude asbelieving that 5 is a prime number—a consequence some finddoubtful. If there was nothing it is like to believe that 5 is a primenumber, then, according to the view that phenomenal consciousness isthe criterion of the mental, many propositional attitudes would failto qualify as genuine mental states. However, much recent work in thephilosophy of mind has been recently devoted to the defense ofso-called "cognitive phenomenology," according to which there issomething it is like to believe that e.g., 5 is a prime number. Seethe SEP entry on consciousness and the papers collected in Bayne andMontague (eds.) (2011).

Many of the philosophers who accept a version of Brentano’sthesis that all mental states exhibit intentionality try to show thatthe mysteries of phenomenal consciousness can either be explained away(i.e., dissolved) or that phenomenal consciousness derives fromintentionality. Daniel Dennett (1988, 1991, 2001) has been the mostconsistent advocate of the view that the distinction betweenphenomenal consciousness and access consciousness has been overratedand thatqualia ought to be ‘quined,’ i.e.,resolutely denied and dispensed with.

So-called “intentionalists” are philosophers who thinkthat phenomenal consciousness can really be explained byintentionality because they think that phenomenal states areintentional states. On the intentionalist account, the phenomenalqualities of an experience are the properties that objects arerepresented as having in the experience. Some intentionalists, likeFred Dretske (1995) and Michael Tye (1995), think that whereasthoughts and propositional attitudes are mental representations withconceptual content,qualia or conscious experiences aremental representations withnonconceptual content (aboutwhich see Dretske 1981, Peacocke 1992, 2001 and the essays in Crane1992). On their view, to have phenomenal features is to have a certainsort of nonconceptual content. On Tye’s (1995) view, forexample, pains are mental representations of bodily parts and thephenomenal experience of a pain is the nonconceptual content of thebodily representation. Other intentionalists such as ElizabethAnscombe (1965) and especially John McDowell (1994), who are skepticalof the distinction between conceptual and nonconceptual content, willappeal to other criteria, e.g., functional role, to account forphenomenal states (see the SEP entry on Nonconceptual mental content).For example, McDowell (1994) argues that the phenomenal content ofexperience can be explained in terms of a suitable notion ofdemonstrative conceptual content.

There are currently two outstanding issues facing an intentionalistapproach to phenomenal experiences. The first is whether theintentionalist account can be extended to the phenomenal character ofall sensory and bodily experiences. This is at present an openquestion (cf. Crane, 2007). The second issue is whether thenonconceptual content of perceptual experiences can be objective inrepresenting and referring to particular objects, or whether onlyconceptual thoughts can be objective and represent or refer toparticular objects. On the one hand, Evans (1982), Dretske (1981,1995) and Peacocke (1992) assume that propositional thought orconceptual content is required to achieve reference to particulars. Onthe other hand, Burge (2010) has offered powerful considerations(mostly derived from perceptual psychology) in favor of theobjectivity of purely perceptual representations. On Burge’sview, perceptual representations are both sensory and objectiverepresentations of the environment. Their nonconceptual content neednot be supplemented by intellectualized (higher-order) representationsof what makes a representation objective in order to provide objectiverepresentations of particulars.

Finally, according to David Rosenthal’s “higher-orderthought” theory of consciousness, what makes a person’smental state conscious is that the person is conscious of it by virtueof having formed a higher-order thought (or HOT) about it.Furthermore, the phenomenal character of a person’s sensoryexperience—what it is like for the person to be in thatstate—arises from the fact that the person has formed a HOTabout it. The problem with the HOT theory of phenomenal consciousnessis that the theory entails that creatures who, like non-human animalsand human babies, lack the ability to form HOTs will be deprived ofphenomenal consciousness—a consequence many will findimplausible (cf. Rosenthal, 1986, 2005). For further discussion, seethe SEP entries onconsciousness and intentionality andhigher-order theories of consciousness.

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Acknowledgments

Thanks to David Chalmers, Steven Davis and Edward N. Zalta forpenetrating comments.