The heart of the eighteenth century Enlightenment is the looselyorganized activity of prominent French thinkers of the mid-decades ofthe eighteenth century, the so-called“philosophes”(e.g., Voltaire, D’Alembert,Diderot, Montesquieu). Thephilosophes constituted aninformal society of men of letters who collaborated on a looselydefined project of Enlightenment exemplified by the project of theEncyclopedia (see below 1.5). However, there are noteworthycenters of Enlightenment outside of France as well. There is arenowned Scottish Enlightenment (key figures are Frances Hutcheson,Adam Smith, David Hume, Thomas Reid), a German Enlightenment (dieAufklärung, key figures of which include Christian Wolff,Moses Mendelssohn, G.E. Lessing and Immanuel Kant), and there are alsoother hubs of Enlightenment and Enlightenment thinkers scatteredthroughout Europe and America in the eighteenth century.

What makes for the unity of such tremendously diverse thinkers underthe label of “Enlightenment”? For the purposes of thisentry, the Enlightenment is conceived broadly. D’Alembert, aleading figure of the French Enlightenment, characterizes hiseighteenth century, in the midst of it, as “the century ofphilosophypar excellence”, because of the tremendousintellectual and scientific progress of the age, but also because ofthe expectation of the age that philosophy (in the broad sense of thetime, which includes the natural and social sciences) woulddramatically improve human life. Guided by D’Alembert’scharacterization of his century, the Enlightenment is conceived hereas having its primary origin in the scientific revolution of the 16thand 17th centuries. The rise of the new science progressivelyundermines not only the ancient geocentric conception of the cosmos,but also the set of presuppositions that had served to constrain andguide philosophical inquiry in the earlier times. The dramatic successof the new science in explaining the natural world promotes philosophyfrom a handmaiden of theology, constrained by its purposes andmethods, to an independent force with the power and authority tochallenge the old and construct the new, in the realms both of theoryand practice, on the basis of its own principles. Taking as the coreof the Enlightenment the aspiration for intellectual progress, and thebelief in the power of such progress to improve human society andindividual lives, this entry includes descriptions of relevant aspectsof the thought of earlier thinkers, such as Hobbes, Locke, Descartes,Bayle, Leibniz, and Spinoza, thinkers whose contributions areindispensable to understanding the eighteenth century as “thecentury of philosophypar excellence”.

The Enlightenment is often associated with its political revolutionsand ideals, especially the French Revolution of 1789. The energycreated and expressed by the intellectual foment of Enlightenmentthinkers contributes to the growing wave of social unrest in France inthe eighteenth century. The social unrest comes to a head in theviolent political upheaval which sweeps away the traditionally andhierarchically structuredancien régime (the monarchy,the privileges of the nobility, the political power of the CatholicChurch). The French revolutionaries meant to establish in place of theancien régime a new reason-based order instituting theEnlightenment ideals of liberty and equality. Though theEnlightenment, as a diverse intellectual and social movement, has nodefinite end, the devolution of the French Revolution into the Terrorin the 1790s, corresponding, as it roughly does, with the end of theeighteenth century and the rise of opposed movements, such asRomanticism, can serve as a convenient marker of the end of theEnlightenment, conceived as an historical period.

For Enlightenment thinkers themselves, however, the Enlightenment isnot an historical period, but a process of social, psychological orspiritual development, unbound to time or place. Immanuel Kant defines“enlightenment” in his famous contribution to debate onthe question in an essay entitled “An Answer to the Question:What is Enlightenment?” (1784), as humankind’s releasefrom its self-incurred immaturity; “immaturity is the inabilityto use one’s own understanding without the guidance ofanother.” Expressing convictions shared among Enlightenmentthinkers of widely divergent doctrines, Kant identifies enlightenmentwith the process of undertaking to think for oneself, to employ andrely on one’s own intellectual capacities in determining what tobelieve and how to act. Enlightenment philosophers from across thegeographical and temporal spectrum tend to have a great deal ofconfidence in humanity’s intellectual powers, both to achievesystematic knowledge of nature and to serve as an authoritative guidein practical life. This confidence is generally paired with suspicionor hostility toward other forms or carriers of authority (such astradition, superstition, prejudice, myth and miracles), insofar asthese are seen to compete with the authority of one’s own reasonand experience. Enlightenment philosophy tends to stand in tensionwith established religion, insofar as the release from self-incurredimmaturity in this age, daring to think for oneself, awakeningone’s intellectual powers, generally requires opposing the roleof established religion in directing thought and action. The faith ofthe Enlightenment – if one may call it that – is that theprocess of enlightenment, of becoming progressively self-directed inthought and action through the awakening of one’s intellectualpowers, leads ultimately to a better, more fulfilled humanexistence.

This entry describes the main tendencies of Enlightenment thought inthe following main sections: (1) The True: Science, Epistemology, andMetaphysics in the Enlightenment; (2) The Good: Political Theory,Ethical Theory and Religion in the Enlightenment; (3) The Beautiful:Aesthetics in the Enlightenment.

• 1. The True: Science, Epistemology and Metaphysics in the Enlightenment
  • 1.1 Rationalism and the Enlightenment
  • 1.2 Empiricism and the Enlightenment
  • 1.3 Skepticism in the Enlightenment
  • 1.4 Science of Man and Subjectivism in the Enlightenment
  • 1.5 Emerging Sciences and theEncyclopedia
• 2. The Good: Political Theory, Ethical Theory and Religion in the Enlightenment
  • 2.1 Political Theory
  • 2.2 Ethical Theory
  • 2.3 Religion and the Enlightenment
• 3. The Beautiful: Aesthetics in the Enlightenment
  • 3.1 French Classicism and German Rationalism
  • 3.2 Empiricism and Subjectivism
  • 3.3 Late Enlightenment Aesthetics
• Bibliography
• Academic Tools
• Other Internet Resources
• Related Entries

1. The True: Science, Epistemology and Metaphysics in the Enlightenment

In this era dedicated to human progress, the advancement of thenatural sciences is regarded as the main exemplification of, and fuelfor, such progress. Isaac Newton’s epochal accomplishment in hisPrincipia Mathematica (1687), which, very briefly described,consists in the comprehension of a diversity of physical phenomena– in particular the motions of heavenly bodies, together withthe motions of sublunary bodies – in few relatively simple,universally applicable, mathematical laws, was a great stimulus to theintellectual activity of the eighteenth century and served as a modeland inspiration for the researches of a number of Enlightenmentthinkers. Newton’s system strongly encourages the Enlightenmentconception of nature as an orderly domain governed by strictmathematical-dynamical laws and the conceptionof ourselvesas capable of knowing those laws and of plumbing the secrets of naturethrough the exercise of our unaided faculties. – The conceptionof nature, and of how we know it, changes significantly with the riseof modern science. It belongs centrally to the agenda of Enlightenmentphilosophy to contribute to the new knowledge of nature, and toprovide a metaphysical framework within which to place and interpretthis new knowledge.

1.1 Rationalism and the Enlightenment

René Descartes’ rationalist system of philosophy is oneof the pillars on which Enlightenment thought rests. Descartes(1596–1650) undertakes to establish the sciences upon a securemetaphysical foundation. The famous method of doubt Descartes employsfor this purpose exemplifies (in part through exaggerating) anattitude characteristic of the Enlightenment. According to Descartes,the investigator in foundational philosophical research ought to doubtall propositions that can be doubted. The investigator determineswhether a proposition is dubitable by attempting to construct apossible scenario under which it is false. In the domain offundamental scientific (philosophical) research, no other authoritybut one’s own conviction is to be trusted, and not one’sown conviction either, until it is subjected to rigorous skepticalquestioning. With his method, Descartes casts doubt upon the senses asauthoritative source of knowledge. He finds that God and theimmaterial soul are both better known, on the basis of innate ideas,than objects of the senses. Through his famous doctrine of the dualismof mind and body, that mind and body are two distinct substances, eachwith its own essence, the material world (allegedly) known through thesenses becomes denominated as an “external” world, insofaras it is external to the ideas with which one immediately communes inone’s consciousness. Descartes’ investigation thusestablishes one of the central epistemological problems, not only ofthe Enlightenment, but also of modernity: the problem of objectivityin our empirical knowledge. If our evidence for the truth ofpropositions about extra-mental material reality is always restrictedto mental content, content before the mind, how can we ever be certainthat the extra-mental reality is not other than we represent it asbeing? Descartes’ solution depends on our having secured priorand certain knowledge of God. In fact, Descartes argues thatall human knowledge (not only knowledge of the material worldthrough the senses) depends on metaphysical knowledge of God.

Despite Descartes’ grounding of all scientific knowledge inmetaphysical knowledge of God, his system contributes significantly tothe advance of natural science in the period. He attacks thelong-standing assumptions of the scholastic-aristotelians whoseintellectual dominance stood in the way of the development of the newscience; he developed a conception of matter that enabled mechanicalexplanation of physical phenomena; and he developed some of thefundamental mathematical resources – in particular, a way toemploy algebraic equations to solve geometrical problems – thatenabled the physical domain to be explained with precise, simplemathematical formulae. Furthermore, his grounding of physics, and allknowledge, in a relatively simple and elegant rationalist metaphysicsprovides a model of a rigorous and complete secular system ofknowledge. Though major Enlightenment thinkers (for example Voltairein hisLetters on the English Nation, 1734) embraceNewton’s physical system in preference to Descartes’,Newton’s system itself depends on Descartes’ earlier work,a dependence to which Newton himself attests.

Cartesian philosophy also ignites various controversies in the latterdecades of the seventeenth century that provide the context ofintellectual tumult out of which the Enlightenment springs. Amongthese controversies are the following: Are mind and body really twodistinct sorts of substances, and if so, what is the nature of each,and how are they related to each other, both in the human being (whichpresumably “has” both a mind and a body) and in a unifiedworld system? If matter is inert (as Descartes claims), what can bethe source of motion and the nature of causality in the physicalworld? And of course the various epistemological problems: the problemof objectivity, the role of God in securing our knowledge, thedoctrine of innate ideas, and others.

Baruch Spinoza’s systematic rationalist metaphysics, which hedevelops in hisEthics (1677) in part in response to problemsin the Cartesian system, is also an important basis for Enlightenmentthought. Spinoza develops, in contrast to Cartesian dualism, anontological monism according to which there is only one substance, Godor nature, with two attributes, corresponding to mind and body.Spinoza’s denial, on the basis of strict philosophicalreasoning, of the existence of a transcendent supreme being, hisidentification of God with nature, gives strong impetus to the strandsof atheism and naturalism that thread through Enlightenmentphilosophy. Spinoza’s rationalist principles also lead him toassert a strict determinism and to deny any role to final causes orteleology in explanation. (See Israel 2001.)

The rationalist metaphysics of Leibniz (1646–1716) is alsofoundational for the Enlightenment, particularly the GermanEnlightenment (die Aufklärung), one prominent expressionof which is the Leibnizian rationalist system of Christian Wolff(1679–1754). Leibniz articulates, and places at the head ofmetaphysics, the great rationalist principle, the principle ofsufficient reason, which states that everything that exists has asufficient reason for its existence. This principle exemplifies thecharacteristic conviction of the Enlightenment that the universe isthoroughly rationally intelligible. The question arises of how thisprinciple itself can be known or grounded. Wolff attempts to derive itfrom the logical principle of non-contradiction (in hisFirstPhilosophy or Ontology, 1730). Criticism of this allegedderivation gives rise to the general question of how formal principlesof logic can possibly serve to ground substantive knowledge ofreality. Whereas Leibniz exerts his influence through scatteredwritings on various topics, some of which elaborate plans for asystematic metaphysics which are never executed by Leibniz himself,Wolff exerts his influence on the German Enlightenment through hisdevelopment of a rationalist system of knowledge in which he attemptsto demonstrate all the propositions of science from first principles,known a priori.

Wolff’s rationalist metaphysics is characteristic of theEnlightenment by virtue of thepretensions of human reasonwithin it, not by reason’s success in establishing its claims.Much the same could be said of the great rationalist philosophers ofthe seventeenth century. Through their articulation of theideal of scientia, of a complete science of reality, composedof propositions derived demonstratively from a priori firstprinciples, these philosophers exert great influence on theEnlightenment. But they fail, rather spectacularly, to realize thisideal. To the contrary, what they bequeath to the eighteenth centuryis metaphysics, in the words of Kant, as “a battlefield ofendless controversies.” However, the controversies themselves– regarding the nature of God, mind, matter, substance, cause,et cetera, and the relations of each of these to the others –provide tremendous fuel to Enlightenment thought.

1.2 Empiricism and the Enlightenment

Despite the confidence in and enthusiasm for human reason in theEnlightenment – it is sometimes called “the Age ofReason” – the rise of empiricism, both in the practice ofscience and in the theory of knowledge, is characteristic of theperiod. The enthusiasm for reason in the Enlightenment is primarilynot for the faculty of reason as an independent source of knowledge,which is embattled in the period, but rather for the human cognitivefaculties generally; the Age of Reason contrasts with an age ofreligious faith, not with an age of sense experience. Though the greatseventeenth century rationalist metaphysical systems of Descartes,Spinoza and Leibniz exert tremendous influence on philosophy in theEnlightenment; moreover, and though the eighteenth-centuryEnlightenment has a rationalist strain (perhaps best exemplified bythe system of Christian Wolff), nevertheless, that theEncyclopedia of Diderot and D’Alembert is dedicated tothree empiricists (Francis Bacon, John Locke and Isaac Newton),signals the ascendency of empiricism in the period.

If the founder of the rationalist strain of the Enlightenment isDescartes, then the founder of the empiricist strain is Francis Bacon(1561–1626). Though Bacon’s work belongs to theRenaissance, the revolution he undertook to effect in the sciencesinspires and influences Enlightenment thinkers. The Enlightenment, asthe age in which experimental natural science matures and comes intoits own, admires Bacon as “the father of experimentalphilosophy.” Bacon’s revolution (enacted in, among otherworks,The New Organon, 1620) involves conceiving the newscience as (1) founded on empirical observation and experimentation;(2) arrived at through the method of induction; and (3) as ultimatelyaiming at, and as confirmed by, enhanced practical capacities (hencethe Baconian motto, “knowledge is power”).

Of these elements of Bacon’s revolution, the point about methoddeserves special emphasis. Isaac Newton’s work, which stands asthe great exemplar of the accomplishments of natural science for theeighteenth century, is, like Bacon’s, based on the inductivemethod. Whereas rationalist of the seventeenth century tend toconceive of scientific knowledge of nature as consisting in a systemin which statements expressing the observable phenomena of nature arededuced from first principles, known a priori, Newton’smethod begins with the observed phenomena of nature and reduces itsmultiplicity to unity by induction, that is, by finding mathematicallaws or principles from which the observed phenomena can be derived orexplained. The evident success of Newton’s“bottom-up” procedure contrasts sharply with the seeminglyendless and fruitless conflicts among philosophers regarding themeaning and validity of first principles of reason, and this contrastnaturally favors the rise of the Newtonian (or Baconian) method ofacquiring knowledge of nature in the eighteenth century.

The tendency of natural science toward progressive independence frommetaphysics in the eighteenth century is correlated with this pointabout method. The rise of modern science in the sixteenth andseventeenth centuries proceeds through its separation from thepresuppositions, doctrines and methodology of theology; naturalscience in the eighteenth century proceeds to separate itself frommetaphysics as well. Newton proves the capacity of natural science tosucceed independently of a priori, clear and certain first principles.The characteristic Enlightenment suspicion of all allegedlyauthoritative claims the validity of which is obscure, which isdirected first of all against religious dogmas, extends to the claimsof metaphysics as well. While there are significant Enlightenmentthinkers who are metaphysicians – again, one thinks of ChristianWolff – the general thrust of Enlightenment thought isanti-metaphysical.

John Locke’sEssay Concerning Human Understanding(1690) is another foundational text of the Enlightenment. A mainsource of its influence is the epistemological rigor that it displays,which is at least implicitly anti-metaphysical. Locke undertakes inthis work to examine the human understanding in order to determine thelimits of human knowledge; he thereby institutes a prominent patternof Enlightenment epistemology. Locke finds the source of all ourideas, the ideas out of which human knowledge is constructed, in thesenses and argues influentially against the rationalists’doctrine of innate ideas. Locke’s sensationalism exerts greatinfluence in the French Enlightenment, primarily through being takenup and radicalized by thephilosophe, Abbé deCondillac. In theTreatise on Sensations (1754), Condillacattempts to explain how all human knowledge arises out of senseexperience. Locke’s epistemology, as developed by Condillac andothers, contributes greatly to the emerging science of psychology inthe period.

Locke and Descartes both pursue a method in epistemology that bringswith it the epistemological problem of objectivity. Both examine ourknowledge by way of examining the ideas we encounter directly in ourconsciousness. This method comes to be called “the way ofideas”. Though neither for Locke nor for Descartes doall of our ideas represent their objects by way ofresembling them (e.g., our idea of God does not represent Godby virtue of resembling God), our alleged knowledge of our environmentthrough the senses does depend largely on ideas that allegedlyresemble external material objects. The way of ideas implies theepistemological problem of how we can know that these ideas do in factresemble their objects. How can we be sure that these objects do notappear one way before the mind and exist in another way (or not atall) in reality outside the mind? George Berkeley, an empiricistphilosopher influenced by John Locke, avoids the problem by assertingthe metaphysics of idealism: the (apparently material) objects ofperception are nothing but ideas before the mind. However,Berkeley’s idealism is less influential in, and characteristicof, the Enlightenment, than the opposing positions of materialism andCartesian dualism. Thomas Reid, a prominent member of the ScottishEnlightenment, attacks the way of ideas and argues that the immediateobjects of our (sense) perception are the common (material) objects inour environment, not ideas in our mind. Reid mounts his defense ofnaïve realism as a defense of common sense over against thedoctrines of the philosophers. The defense of common sense, and therelated idea that the results of philosophy ought to be of use tocommon people, are characteristic ideas of the Enlightenment,particularly pronounced in the Scottish Enlightenment.

1.3 Skepticism in the Enlightenment

Skepticism enjoys a remarkably strong place in Enlightenmentphilosophy, given that confidence in our intellectual capacities toachieve systematic knowledge of nature is a leading characteristic ofthe age. This oddity is at least softened by the point that muchskepticism in the Enlightenment is merely methodological, a tool meantto serve science, rather than a position embraced on its own account.The instrumental role for skepticism is exemplified prominently inDescartes’Meditations on First Philosophy (1641), inwhich Descartes employs radical skeptical doubt to attack prejudicesderived from learning and from sense experience and to search outprinciples known with certainty which may serve as a secure foundationfor a new system of knowledge. Given the negative, critical,suspicious attitude of the Enlightenment towards doctrinestraditionally regarded as well founded, it is not surprising thatEnlightenment thinkers employ skeptical tropes (drawn from the ancientskeptical tradition) to attack traditional dogmas in science,metaphysics and religion.

However, skepticism is not merely a methodological tool in the handsof Enlightenment thinkers. The skeptical cast of mind is one prominentmanifestation of the Enlightenment spirit. The influence of PierreBayle, another founding figure of the Enlightenment, testifies tothis. Bayle was a French Protestant, who, like many Europeanphilosophers of his time, was forced to live and work in politicallyliberal and tolerant Holland in order to avoid censorship and prison.Bayle’sHistorical and Critical Dictionary (1697), astrange and wonderful book, exerts great influence on the age. Theform of the book is intimidating: a biographical dictionary, with longscholarly entries on obscure figures in the history of culture,interrupted by long scholarly footnotes, which are in turn interruptedby further footnotes. Rarely has a work with such intimidatingscholarly pretentions exerted such radical and liberating influence inthe culture. It exerts this influence through its skepticalquestioning of religious, metaphysical, and scientific dogmas.Bayle’s eclecticism and his tendency to follow arguments withoutpre-arranging their conclusions make it difficult to categorize histhought. It is the attitude of inquiry that Bayle displays, ratherthan any doctrine he espouses, that mark his as distinctivelyEnlightenment thought. He is fearless and presumptuous in questioningall manner of dogma. His attitude of inquiry resembles both that ofDescartes’ meditator and that of the person undergoingenlightenment as Kant defines it, the attitude of coming to think foroneself, of daring to know. This epistemological attitude, as manifestin distrust of authority and reliance on one’s own capacity tojudge, expresses the Enlightenment values of individualism andself-determination.

This skeptical/critical attitude underlies a significant tension inthe age. While it is common to conceive of the Enlightenment assupplanting the authority of tradition and religious dogma with theauthority of reason, in fact the Enlightenment is characterized by acrisis of authority regarding any belief. This is perhaps bestillustrated with reference to David Hume’s skepticism, asdeveloped in Book One ofATreatise of Human Nature(1739–40) and in his laterEnquiries Concerning HumanUnderstanding (1748). While one might take Hume’sskepticism to imply that he is an outlier with respect to theEnlightenment, it is more convincing to see Hume’s skepticism asa flowering of a crisis regarding authority in belief that is internalto the Enlightenment. Hume articulates a variety of skepticisms. His“skepticism with regard to the senses” is structured bythe epistemological problem bound up with the way of ideas, describedabove. Hume also articulates skepticism with regard to reason in anargument that is anticipated by Bayle. Hume begins this argument bynoting that, though rules or principles in demonstrative sciences arecertain or infallible, given the fallibility of our faculties, ourapplications of such rules or principles in demonstrative inferencesyield conclusions that cannot be regarded as certain or infallible. Onreflection, our conviction in the conclusions of demonstrativereasoning must be qualified by an assessment of the likelihood that wemade a mistake in our reasoning. Thus, Hume writes, “allknowledge degenerates into probability” (Treatise,I.iv.i). Hume argues further that, given this degeneration, for anyjudgment, our assessment of the likelihood that we made a mistake, andthe corresponding diminution of certainty in the conclusion, isanother judgment about which we ought make a further assessment, whichleads to a further diminution of certainty in our original conclusion,leading “at last [to] a total extinction of belief andevidence”. Hume also famously questions the justification ofinductive reasoning and causal reasoning. According to Hume’sargument, since in causal reasoning we take our past observations toserve as evidence for judgments regarding what will happen inrelevantly similar circumstances in the future, causal reasoningdepends on the assumption that the future course of nature willresemble the past; and there is no non-circular justification of thisessential assumption. Hume concludes that we have no rationaljustification for our causal or inductive judgments. Hume’sskeptical arguments regarding causal reasoning are more radical thanhis skeptical questioning of reason as such, insofar as they call intoquestion evenexperience itself as a ground for knowledge andimplicitly challenge the credentials of Newtonian science itself, thevery pride of the Enlightenment. The question implicitly raised byHume’s powerful skeptical arguments is whetheranyepistemological authority at all can withstand critical scrutiny. TheEnlightenment begins by unleashing skepticism in attacking limited,circumscribed targets, but once the skeptical genie is out of thebottle, it becomes difficult to maintain conviction in any authority.Thus, the despairing attitude that Hume famously expresses in theconclusion to Book One of theTreatise, as the consequence ofhis epistemological inquiry, while it clashes with the self-confidentand optimistic attitude we associate with the Enlightenment, in factreflects an essential possibility in a distinctive Enlightenmentproblematic regarding authority in belief.

1.4 Science of Man and Subjectivism in the Enlightenment

Though Hume finds himself struggling with skepticism in the conclusionof Book One of theTreatise, the project of the work as heoutlines it is not to advance a skeptical viewpoint, but to establisha science of the mind. Hume is one of many Enlightenment thinkers whoaspire to be the “Newton of the mind”; he aspires toestablish the basic laws that govern the elements of the human mind inits operations. Alexander Pope’s famous couplet inAn Essayon Man (1733) (“Know then thyself, presume not God to scan/The proper study of mankind is man”) expresses well the intenseinterest humanity gains in itself within the context of theEnlightenment, as a partial substitute for its traditional interest inGod and the transcendent domain. Just as the sun replaces the earth asthe center of our cosmos in Copernicus’ cosmological system, sohumanity itself replaces God at the center of humanity’sconsciousness in the Enlightenment. Given the Enlightenment’spassion for science, the self-directed attention naturally takes theform of the rise of the scientific study of humanity in theperiod.

The enthusiasm for the scientific study of humanity in the periodincorporates a tension or paradox concerning the place of humanity inthe cosmos, as the cosmos is re-conceived in the context ofEnlightenment philosophy and science. Newton’s success early inthe Enlightenment of subsuming the phenomena of nature under universallaws of motion, expressed in simple mathematical formulae, encouragesthe conception of nature as a very complicated machine, whose partsare material and whose motions and properties are fully accounted forby deterministic causal laws. But if our conception of nature is of anexclusively material domain governed by deterministic, mechanicallaws, and if we at the same time deny the place of the supernatural inthe cosmos, then how does humanity itself fit into the cosmos? On theone hand, the achievements of the natural sciences in general are thegreat pride of the Enlightenment, manifesting the excellence ofdistinctively human capacities. The pride and self-assertiveness ofhumanity in the Enlightenment expresses itself, among other ways, inhumanity’s making the study of itself its central concern. Onthe other hand, the study of humanity in the Enlightenment typicallyyields a portrait of us that is the opposite of flattering orelevating. Instead of being represented as occupying a privilegedplace in nature, as made in the image of God, humanity is representedtypically in the Enlightenment as a fully natural creature, devoid offree will, of an immortal soul, and of a non-natural faculty ofintelligence or reason. The very title of J.O. de La Mettrie’sMan a Machine (1748), for example, seems designed to deflatehumanity’s self-conception, and in this respect it ischaracteristic of the Enlightenment “science of man”. Itis true of a number of works of the Enlightenment, perhaps especiallyworks in the more radical French Enlightenment – notable hereare Helvétius’sOf the Spirit (1758) and Barond’Holbach’sSystem of Nature (1770) – thatthey at once express the remarkable self-assertiveness of humanitycharacteristic of the Enlightenment in their scientific aspirationswhile at the same time painting a portrait of humanity thatdramatically deflates its traditional self-image as occupying aprivileged position in nature.

The methodology of epistemology in the period reflects a similartension. Given the epistemological role of Descartes’ famous“cogito, ergo sum” in his system of knowledge,one might see Descartes’ epistemology as already marking thetransition from an epistemology privileging knowledge of God to onethat privileges self-knowledge instead. However, in Descartes’epistemology, it remains true that knowledge of God serves as thenecessary foundation for all human knowledge. Hume’sTreatise displays such a re-orientation less ambiguously. Asnoted, Hume means his work to comprise a science of the mind or ofman. In the Introduction, Hume describes the science of man aseffectively a foundation for all the sciences since all sciences“lie under the cognizance of men, and are judged of by theirpowers and faculties.” In other words, since all science ishuman knowledge, scientific knowledgeof humanity is thefoundation of the sciences. Hume’s placing the science of man atthe foundation of all the sciences both exemplifies the privilegeafforded to “mankind’s study of man” within theEnlightenment and provides an interpretation of it. But Hume’smethodological privileging of humanity in the system of sciencescontrasts sharply with what he says in the body of his science abouthumanity. In Hume’s science of man, reason as a faculty ofknowledge is skeptically attacked and marginalized; reason isattributed to other animals as well; belief is shown to be grounded incustom and habit; and free will is denied. So, even as knowledge ofhumanity supplants knowledge of God as the keystone of the system ofknowledge, the scientific perspective on humanity starkly challengeshumankind’s self-conception as occupying a privileged positionin the order of nature.

Immanuel Kant explicitly enacts a revolution in epistemology modeledon the Copernican in astronomy. As characteristic of Enlightenmentepistemology, Kant, in hisCritique of Pure Reason (1781,second edition 1787) undertakes both to determine the limits of ourknowledge, and at the same time to provide a foundation of scientificknowledge of nature, and he attempts to do this by examining our humanfaculties of knowledge critically. Even as he draws strict limits torational knowledge, he attempts to defend reason as a faculty ofknowledge, as playing a necessary role in natural science, in the faceof skeptical challenges that reason faces in the period. According toKant, scientific knowledge of nature is not merely knowledge of whatin fact happens in nature, but knowledge of the causal lawsof nature according to which what in fact happensmusthappen. But how is knowledge of necessary causal connection in naturepossible? Hume’s investigation of the idea of cause had madeclear that we cannot know causal necessity through experience;experience teaches us at most what in fact happens, not whatmust happen. In addition, Kant’s own earlier critiqueof principles of rationalism had convinced him that the principles of(“general”) logic also cannot justify knowledge ofreal necessary connections (in nature); the formal principleof non-contradiction can ground at best the deduction of oneproposition from another, but not the claim that oneproperty orevent must follow from another in thecourse of nature. The generalized epistemological problem Kantaddresses in theCritique of Pure Reason is: how is sciencepossible (including natural science, mathematics, metaphysics), giventhat all such knowledge must be (or include) knowledge of real,substantive (not merely logical or formal) necessities. Put in theterms Kant defines, the problem is: how is synthetic, a prioriknowledge possible?

According to Kant’s Copernican Revolution in epistemologyaddressed to this problem, objects must conform themselves to humanknowledge rather than knowledge to objects. Certain cognitive formslie ready in the human mind – prominent examples are the pureconcepts of substance and cause and the forms of intuition, space andtime; given sensible representations must conform themselves to theseforms in order for human experience (as empirical knowledge of nature)to be possible at all. We can acquire scientific knowledge of naturebecause we constitute it a priori according to certain cognitiveforms; for example, we can know nature as a causally ordered domainbecause we originally synthesize a priori the given manifold ofsensibility according to the category of causality, which has itssource in the human mind.

Kant saves rational knowledge of nature by limiting rational knowledgeto nature. According to Kant’s argument, we can have rationalknowledge only of the domain of possible experience, not ofsupersensible objects such as God and the soul. Moreover Kant’ssolution brings with it a kind of idealism: given the mind’srole in constituting objects of experience, we know objects only asappearances, only as they appear according to our faculties,not as they are in themselves. This is the subjectivism ofKant’s epistemology. Kant’s epistemology exemplifiesEnlightenment thought by replacing the theocentric conception ofknowledge of the rationalist tradition with an anthropocentricconception.

However, Kant means his system to make room for humanity’spractical and religious aspirations toward the transcendent as well.According to Kant’s idealism, the realm of nature is limited toa realm of appearances, and we can intelligibly think supersensibleobjects such as God, freedom and the soul, though we cannot know them.Through the postulation of a realm of unknowable noumena (things inthemselves) over against the realm of nature as a realm ofappearances, Kant manages to make place for practical concepts thatare central to our understanding of ourselves even while grounding ourscientific knowledge of nature as a domain governed by deterministiccausal laws. Though Kant’s idealism is highly controversial fromits initial publication, a main point in its favor, according to Kanthimself, is that it reconciles, in a single coherent tension, the maintension between the Enlightenment’s conception of nature, asordered according to deterministic causal laws, and theEnlightenment’s conception of ourselves, as morally free, ashaving dignity, and as perfectible.

1.5 Emerging Sciences and theEncyclopedia

The commitment to careful observation and description of phenomena asthe starting point of science, and then the success at explaining andaccounting for observed phenomena through the method of induction,naturally leads to the development of new sciences for new domains inthe Enlightenment. Many of the human and social sciences have theirorigins in the eighteenth century (e.g., history, anthropology,aesthetics, psychology, economics, even sociology), though most areonly formally established as autonomous disciplines later. Theemergence of new sciences is aided by the development of newscientific tools, such as models for probabilistic reasoning, a kindof reasoning that gains new respect and application in the period.Despite the multiplication of sciences in the period, the idealremains to comprehend the diversity of our scientific knowledge as aunified system of science; however, this ideal of unity is generallytaken as regulative, as an ideal to emerge in the ever-recedingend-state of science, rather than as enforced from the beginning byregimenting science under a priori principles.

As exemplifying these and other tendencies of the Enlightenment, onework deserves special mention: theEncyclopedia, edited byDenis Diderot and Jean La Rond d’Alembert. TheEncyclopedia (subtitled: “systematic dictionary ofthe sciences, arts and crafts”) was published in 28 volumes(17 of text, 11 of plates) over 21 years (1751–1772), andconsists of over 70,000 articles, contributed by over 140contributors, among them many of the luminaries of the FrenchEnlightenment. The work aims to provide a compendium of existing humanknowledge to be transmitted to subsequent generations, a transmissionintended to contribute to the progress and dissemination of humanknowledge and to a positive transformation of human society. Theorientation of theEncyclopedia is decidedly secular andimplicitly anti-authoritarian. Accordingly, the French state of theancien régime censors the project, and it is completedonly through the persistence of Diderot. The collaborative nature ofthe project, especially in the context of state opposition,contributes significantly to the formation of a shared sense ofpurpose among the wide variety of intellectuals who belong to theFrench Enlightenment. The knowledge contained in theEncyclopedia is self-consciously social both in itsproduction – insofar as it is immediately the product of whatthe title page calls “a society of men of letters” –and in its address – insofar as it is primarily meant as aninstrument for the education and improvement of society. It is astriking feature of theEncyclopedia, and one by virtue ofwhich it exemplifies the Baconian conception of science characteristicof the period, that its entries cover the whole range and scope ofknowledge, from the most abstract theoretical to the most practical,mechanical and technical.

2. The Good: Political Theory, Ethical Theory and Religion in the Enlightenment

2.1 Political Theory

The Enlightenment is most identified with its politicalaccomplishments. The era is marked by three political revolutions,which together lay the basis for modern, republican, constitutionaldemocracies: The English Revolution (1688), the American Revolution(1775–83), and the French Revolution (1789–99). Thesuccess at explaining and understanding the natural world encouragesthe Enlightenment project of re-making the social/political world, inaccord with the models we allegedly find in our reason. Enlightenmentphilosophers find that the existing social and political orders do notwithstand critical scrutiny. Existing political and social authorityis shrouded in religious myth and mystery and founded on obscuretraditions. The criticism of existing institutions is supplementedwith the positive work of constructing in theory the model ofinstitutions as they ought to be. We owe to this period the basicmodel of government founded upon the consent of the governed; thearticulation of the political ideals of freedom and equality and thetheory of their institutional realization; the articulation of a listof basic individual human rights to be respected and realized by anylegitimate political system; the articulation and promotion oftoleration of religious diversity as a virtue to be respected in awell ordered society; the conception of the basic political powers asorganized in a system of checks and balances; and other now-familiarfeatures of western democracies. However, for all the enduringaccomplishments of Enlightenment political philosophy, it is not clearthat human reason proves powerful enough to put a concrete, positiveauthoritative ideal in place of the objects of its criticism. As inthe epistemological domain, reason shows its power more convincinglyin criticizing authorities than in establishing them. Here too thequestion of the limits of reason is one of the main philosophicallegacies of the period. These limits are arguably vividly illustratedby the course of the French Revolution. The explicit ideals of theFrench Revolution are the Enlightenment ideals of individual freedomand equality; but, as the revolutionaries attempt to devise rational,secular institutions to put in place of those they have violentlyoverthrown, eventually they have recourse to violence and terror inorder to control and govern the people. The devolution of the FrenchRevolution into the Reign of Terror is perceived by many as provingthe emptiness and hypocrisy of Enlightenment reason, and is one of themain factors which account for the end of the Enlightenment as anhistorical period.

The political revolutions of the Enlightenment, especially the Frenchand the American, were informed and guided to a significant extent byprior political philosophy in the period. Though Thomas Hobbes, in hisLeviathan (1651), defends the absolute power of the politicalsovereign, and is to that extent opposed to the revolutionaries andreformers in England, this work is a founding work of Enlightenmentpolitical theory. Hobbes’ work originates the modern socialcontract theory, which incorporates Enlightenment conceptions of therelation of the individual to the state. According to the generalsocial contract model, political authority is grounded in an agreement(often understood as ideal, rather than real) among individuals, eachof whom aims in this agreement to advance his rational self-interestby establishing a common political authority over all. Thus, accordingto the general contract model (though this is more clear in latercontract theorists such as Locke and Rousseau than in Hobbes himself),political authority is grounded not in conquest, natural or divinelyinstituted hierarchy, or in obscure myths and traditions, but ratherin the rational consent of the governed. In initiating this model,Hobbes takes a naturalistic, scientific approach to the question ofhow political society ought to be organized (against the background ofa clear-eyed, unsentimental conception of human nature), and thusdecisively influences the Enlightenment process of secularization andrationalization in political and social philosophy.

Baruch Spinoza also greatly contributes to the development ofEnlightenment political philosophy in its early years. Themetaphysical doctrines of theEthics (1677) lay thegroundwork for his influence on the age. Spinoza’s argumentsagainst Cartesian dualism and in favor of substance monism, the claimin particular that there can only be one substance, God or nature, wastaken to have radical implications in the domains of politics, ethicsand religion throughout the period. Spinoza’s employment ofphilosophical reason leads to the denial of the existence of atranscendent, creator, providential, law-giving God; this establishesthe opposition between the teachings of philosophy, on the one hand,and the traditional orienting practical beliefs (moral, religious,political) of the people, on the other hand, an opposition that is oneimportant aspect of the culture of the Enlightenment. In his mainpolitical work,Tractatus Theologico-Politicus (1677),Spinoza, building on his rationalist naturalism, opposes superstition,argues for toleration and the subordination of religion to the state,and pronounces in favor of qualified democracy. Liberalism is perhapsthe most characteristic political philosophy of the Enlightenment, andSpinoza, in this text primarily, is one of its originators.

However, John Locke’sSecond Treatise ofGovernment (1690) is the classical source of modern liberalpolitical theory. In hisFirst Treatise of Government, Lockeattacks Robert Filmer’sPatriarcha (1680), whichepitomizes the sort of political theory the Enlightenment opposes.Filmer defends the right of kings to exercise absolute authority overtheir subjects on the basis of the claim that they inherit theauthority God vested in Adam at creation. Though Locke’sassertion of the natural freedom and equality of human beings in theSecond Treatise is starkly and explicitly opposed toFilmer’s view, it is striking that the cosmology underlyingLocke’s assertions is closer to Filmer’s than toSpinoza’s. According to Locke, in order to understand the natureand source of legitimate political authority, we have to understandour relations in the state of nature. Drawing upon the natural lawtradition, Locke argues that it is evident to our natural reason thatwe are all absolutely subject to our Lord and Creator, but that, inrelation to each other, we exist naturally in a state of equality“wherein all the power and jurisdiction is reciprocal, no onehaving more than another” (Second Treatise, §4).We also exist naturally in a condition of freedom, insofar as we maydo with ourselves and our possessions as we please, within theconstraints of the fundamental law of nature. The law of nature“teaches all mankind … that, being all equal andindependent, no one ought to harm another in his life, health,liberty, or possessions” (§6). That we are governed in ournatural condition by such a substantive moral law, legislated by Godand known to us through our natural reason, implies that the state ofnature is not Hobbes’ war of all against all. However, sincethere is lacking any human authority over all to judge of disputes andenforce the law, it is a condition marred by“inconveniencies”, in which possession of natural freedom,equality and possessions is insecure. According to Locke, werationally quit this natural condition by contracting together to setover ourselves a political authority, charged with promulgating andenforcing a single, clear set of laws, for the sake of guaranteeingour natural rights, liberties and possessions. The civil, politicallaw, founded ultimately upon the consent of the governed, does notcancel the natural law, according to Locke, but merely serves to drawthat law closer. “[T]he law of nature stands as an eternal ruleto all men” (§135). Consequently, when establishedpolitical power violates that law, the people are justified inoverthrowing it. Locke’s argument for the right to revoltagainst a government that opposes the purposes for which legitimategovernment is taken by some to justify the political revolution in thecontext of which he writes (the English revolution) and, almost ahundred years later, by others to justify the American revolution aswell.

Though Locke’s liberalism has been tremendously influential, hispolitical theory is founded on doctrines of natural law and religionthat are not nearly as evident as Locke assumes. Locke’sreliance on the natural law tradition is typical of Enlightenmentpolitical and moral theory. According to the natural law tradition, asthe Enlightenment makes use of it, we can know through the use of ourunaided reason that we all – all human beings, universally– stand in particular moral relations to each other. The claimthat we can apprehend through our unaided reason auniversalmoral order exactly because moral qualities and relations (inparticular human freedom and equality) belong to the nature of things,is attractive in the Enlightenment for obvious reasons. However, asnoted above, the scientific apprehension of nature in the period doesnot support, and in fact opposes, the claim that the alleged moralqualities and relations (or, indeed, thatany moral qualitiesand relations) arenatural. According to a commonEnlightenment assumption, as humankind clarifies the laws of naturethrough the advance of natural science and philosophy, the true moraland political order will be revealed with it. This view is expressedexplicitly by thephilosophe Marquis de Condorcet, in hisSketch for a Historical Picture of the Progress of the HumanMind (published posthumously in 1795 and which, perhaps betterthan any other work, lays out the paradigmatically Enlightenment viewof history of the human race as a continual progress to perfection).But, in fact, advance in knowledge of the laws of nature in thescience of the period does not help with discernment of a naturalpolitical or moral order. This asserted relationship between naturalscientific knowledge and the political and moral order is under greatstress already in the Enlightenment. With respect to Lockeanliberalism, though his assertion of the moral and political claims(natural freedom, equality, et cetera) continues to have considerableforce for us, the grounding of these claims in a religious cosmologydoes not. The question of how to ground our claims to natural freedomand equality is one of the main philosophical legacies of theEnlightenment.

The rise and development of liberalism in Enlightenment politicalthought has many relations with the rise of the mercantile class (thebourgeoisie) and the development of what comes to be called“civil society”, the society characterized by work andtrade in pursuit of private property. Locke’sSecondTreatise contributes greatly to the project of articulating apolitical philosophy to serve the interests and values of thisascending class. Locke claims that the end or purpose of politicalsociety is the preservation and protection of property (though hedefines property broadly to include not only external property butlife and liberties as well). According to Locke’s famousaccount, persons acquire rightful ownership in external things thatare originally given to us all by God as a common inheritance,independently of the state and prior to its involvement, insofar as we“mix our labor with them”. The civil freedom that Lockedefines, as something protected by the force of political laws, comesincreasingly to be interpreted as the freedom to trade, to exchangewithout the interference of governmental regulation. Within thecontext of the Enlightenment, economic freedom is a salientinterpretation of the individual freedom highly valued in the period.Adam Smith, a prominent member of the Scottish Enlightenment,describes in hisAn Inquiry into the Nature and Causes of theWealth of Nations (1776) some of the laws of civil society, as asphere distinct from political society as such, and thus contributessignificantly to the founding of political economy (later calledmerely “economics”). His is one of many voices in theEnlightenment advocating for free trade and for minimal governmentregulation of markets. The trading house floor, in which people ofvarious nationalities, languages, cultures, religions come togetherand trade, each in pursuit of his own self-interest, but, through thispursuit, supplying the wants of their respective nations andincreasing its wealth, represents for some Enlightenment thinkers thebenign, peaceful, universal rational order that they wish to seereplace the violent, confessional strife that characterized thethen-recent past of Europe.

However, the liberal conception of the government as properlyprotecting economic freedom of citizens and private property comesinto conflict in the Enlightenment with the value of democracy. JamesMadison confronts this tension in the context of arguing for theadoption of the U.S. Constitution (in his Federalist #10). Madisonargues that popular government (pure democracy) is subject to the evilof factions; in a pure democracy, a majority bound together by aprivate interest, relative to the whole, has the capacity to imposeits particular will on the whole. The example most on Madison’smind is that those without property (the many) may seek to bring aboutgovernmental re-distribution of the property of the propertied class(the few), perhaps in the name of that other Enlightenment ideal,equality. If, as in Locke’s theory, the government’sprotection of an individual’s freedom is encompassed within thegeneral end of protecting a person’s property, then, as Madisonargues, the proper form of the government cannot be pure democracy,and the will of the people must be officially determined in some otherway than by directly polling the people.

Jean-Jacques Rousseau’s political theory, as presented in hisOn the Social Contract (1762), presents a contrast to theLockean liberal model. Though commitment to the political ideals offreedom and equality constitutes a common ground for Enlightenmentpolitical philosophy, it is not clear not only how these values have ahome in nature as Enlightenment science re-conceives it, but also howconcretely to interpret each of these ideals and how properly tobalance them against each other. Contrary to Madison, Rousseau arguesthat direct (pure) democracy is the only form of government in whichhuman freedom can be realized. Human freedom, according toRousseau’s interpretation, is possible only through governanceaccording to what he calls “the general will,” which isthe will of the body politic, formed through the original contract,concretely determined in an assembly in which all citizensparticipate. Rousseau’s account intends to avert the evils offactions by structural elements of the original contract. The contractconsists in the self-alienation by each associate of all rights andpossessions to the body politic. Because each alienates all, each isan equal member of the body politic, and the terms and conditions arethe same for all. The emergence of factions is avoided insofar as thegood of each citizen is, and is understood to be, equally (becausewholly) dependent on the general will. Legislation supports thisidentification with the general will by preserving the originalequality established in the contract, prominently through maintaininga measure of economic equality. Rousseau’s account of the idealrelation of the individual citizen to the state differs fromLocke’s; in Rousseau’s account, the individual must beactively engaged in political life in order to maintain theidentification of his supremely authoritative will with the generalwill, whereas in Locke the emphasis is on the limits of governmentalauthority with respect to the expressions of the individual will.Though Locke’s liberal model is more representative of theEnlightenment in general, Rousseau’s political theory, which insome respects presents a revived classical model modified within thecontext of Enlightenment values, in effect poses many of the enduringquestions regarding the meaning and interpretation of politicalfreedom and equality within the modern state.

Both Madison and Rousseau, like most political thinkers of the period,are influenced by Baron de Montesquieu’sThe Spirit of theLaws (1748), which is one of the founding texts of modernpolitical theory. Though Montesquieu’s treatise belongs to thetradition of liberalism in political theory, given his scientificapproach to social, legal and political systems, his influence extendsbeyond this tradition. Montesquieu argues that the system oflegislation for a people varies appropriately with the particularcircumstances of the people. He provides specific analysis of howclimate, fertility of the soil, population size, et cetera, affectlegislation. He famously distinguishes three main forms ofgovernments: republics (which can either be democratic oraristocratic), monarchies and despotisms. He describes leadingcharacteristics of each. His argument that functional democraciesrequire the population to possess civic virtue in high measure, avirtue that consists in valuing public good above private interest,influences later Enlightenment theorists, including both Rousseau andMadison. He describes the threat of factions to which Madison andRousseau respond in different (indeed opposite) ways. He provides thebasic structure and justification for the balance of political powersthat Madison later incorporates into the U.S. Constitution.

It is striking how unenlightened many of the Enlightenment’scelebrated thinkers are concerning issues of race and of gender(regarding race, seeRace and Enlightenment: A Reader, editedby Emmanuel Chukwudi Eze). For all the public concern with theallegedly universal “rights of man” in the Enlightenment,the rights of women and of non-white people are generally overlookedin the period. (Mary Wollstonecraft’sVindication of theRights of Woman (1792) is a noteworthy exception.) WhenEnlightenment thinkers do turn their attention to the social standingof women or of non-white people, they tend to spout unreasonedprejudice. Moreover, while the philosophies of the Enlightenmentgenerally aspire or pretend to universal truth, unattached toparticular time, place or culture, Enlightenment writings are rifewith rank ethno- and Eurocentrism, often explicit.

In the face of such tensions within the Enlightenment, one response isto affirm the power of the Enlightenment to improve humanity andsociety long beyond the end of the eighteenth century, indeed, down tothe present day and into the future. This response embraces theEnlightenment and interprets more recent emancipation movements andachievement of recognition of the rights and dignity of traditionallyoppressed and marginalized groups as expressions of Enlightenmentideals and aspirations. Critics of the Enlightenment responddifferently to such tensions. Critics see them as symptoms ofdisorder, ideology, perversity, futility or falsehood that afflict thevery core of the Enlightenment itself. (See James Schmidt’s“What Enlightenment Project?” for discussion of critics ofthe Enlightenment.) Famously, Adorno and Horkheimer interpret Nazideath camps as the result of “the dialectic of theEnlightenment”, as what historically becomes of the supremacy ofinstrumental reason asserted in the Enlightenment. As another example,we may point to some post-modern feminists, who argue, in oppositionto the liberal feminists who embrace broadly Enlightenment ideals andconceptions, that the essentialism and universalism associated withEnlightenment ideals are both false and intrinsically hostile to theaspirations to self-realization of women and of other traditionallyoppressed groups. (See Strickland and the essays in Akkerman andStuurman.) This entry is not the place to delineate strains ofopposition to the Enlightenment, but it is worth noting thatpost-Enlightenment social and political struggles to achieve equalityor recognition for traditionally marginalized or oppressed groups aresometimes self-consciously grounded in the Enlightenment and sometimesmarked by explicit opposition to the Enlightenment’s conceptionsor presuppositions.

2.2 Ethical Theory

Many of the leading issues and positions of contemporary philosophicalethics take shape within the Enlightenment. Prior to the Enlightenmentin the West, ethical reflection begins from and orients itself aroundreligious doctrines concerning God and the afterlife. The highest goodof humanity, and, accordingly, the content and grounding of moralduties, are conceived in immediately religious terms. During theEnlightenment, this changes, certainly within philosophy, but to somesignificant degree, within the population of western society at large.As the processes of industrialization, urbanization, and disseminationof education advance in this period, happiness in this life, ratherthan union with God in the next, becomes the highest end for more andmore people. Also, the violent religious wars that bloody Europe inthe early modern period motivate the development of secular,this-worldly ethics, insofar as they indicate the failure of religiousdoctrines concerning God and the afterlife to establish a stablefoundation for ethics. In the Enlightenment, philosophical thinkersconfront the problem of developing ethical systems on a secular,broadly naturalistic basis for the first time since the rise ofChristianity eclipsed the great classical ethical systems. However,the changes in our understanding of nature and cosmology, effected bymodern natural science, make recourse to the systems of Plato andAristotle problematic. The Platonic identification of the good withthe real and the Aristotelian teleological understanding of naturalthings are both difficult to square with the Enlightenment conceptionof nature. The general philosophical problem emerges in theEnlightenment of how to understand the source and grounding of ethicalduties, and how to conceive the highest good for human beings, withina secular, broadly naturalistic context, and within the context of atransformed understanding of the natural world.

In ethical thought, as in political theory, Hobbes’ thought isan important provocation in the Enlightenment. Hobbes understands whatis good, as the end of human action, to be “whatsoever is theobject of any man’s appetite or desire,” and evil to be“the object of his hate, and aversion,” “there beingnothing simply and absolutely so; nor any common rule of good andevil, to be taken from the nature of the objects themselves”(Leviathan, chapter 6). Hobbes’ conception of humanbeings as fundamentally motivated by their perception of what is intheir own best interest implies the challenge, important forEnlightenment moral philosophy, to construct moral duties of justiceand benevolence out of such limited materials. The basis of humanaction that Hobbes posits is immediately intelligible and even sharedwith other animals to some extent; a set of moral duties constructedon this basis would also be intelligible, de-mystified, and fit withinthe larger scheme of nature. Bernard Mandeville is sometimes groupedwith Hobbes in the Enlightenment, especially by critics of them both,because he too, in his popularFable of the Bees; or, PrivateVices, Public Benefits (1714), sees people as fundamentallymotivated by their perceived self-interest, and then undertakes totell a story about how moral virtue, which involves conqueringone’s own appetite and serving the interests of others, can beunderstood to arise on this basis.

Samuel Clarke, an influential rationalist British thinker early in theEnlightenment, undertakes to show in hisDiscourse concerning theUnchangeable Obligations of Natural Religion (1706), againstHobbes, that the absolute difference between moral good and moral evillies in the immediately discernible nature of things, independently ofany compacts or positive legislation by God or human beings. Clarkewrites that “in men’s dealing … one with another,it is undeniably more fit, absolutely and in the nature of the thingitself, that all men should endeavor to promote the universal good andwelfare of all; than that all men should be continually contriving theruin and destruction of all”. Likewise for the rest of whatmorality enjoins upon us. According to Clarke, that some actions(those we call morally good or required) are “fit to bedone” and others not fit is grounded upon the immediatelyevident relations in which things stand to each other in nature, justas “the proportions of lines or numbers” are evident tothe rational perception of a reasonable being. Similarly, ChristianWolff’s rationalist practical philosophy also grounds moralduties in an objective rational order. However, the objective qualityon which moral requirements are grounded for Wolff is not the“fitness” of things to be done but rather theirperfection. Wolff counts as a founder of theAufklärungin part because of his attempted derivation of ethical duties from anorder of perfection in things, discernable through reason,independently of divine commands.

Rationalist ethics so conceived faces the following obstacles in theEnlightenment. First, as implied above, it becomes increasinglyimplausible that the objective, mind-independent order is really asrationalist ethicists claim it to be. Second, even if the objectiverealm were ordered as the rationalist claims, it remains unclear howthis order gives rise (on its own, as it were) to obligations bindingon our wills. David Hume famously exposes the fallacy of deriving aprescriptive statement (that one ought to perform some action) from adescription of how things stand in relation to each other in nature.Prima facie, there is a gap between the rationalist’s objectiveorder and a set of prescriptions binding on our wills; if a supremelegislator must be re-introduced in order to make the conformity ofour actions to that objective order binding on our wills, then thealleged existence of the objective moral order does not do the workthe account asks of it in the first place.

Alongside the rationalist strand of ethical philosophy in theEnlightenment, there is also a very significant empiricist strand.Empirical accounts of moral virtue in the period are distinguished,both by grounding moral virtue on an empirical study of human nature,and by grounding cognition of moral duties and moral motivation inhuman sensibility, rather than in reason. The Third Earl ofShaftesbury, author of the influential workCharacteristics ofMen, Manners, Opinions, Times (1711), is a founding figure of theempiricist strand. Shaftesbury, like Clarke, is provoked byHobbes’ egoism to provide a non-egoistic account of moralvirtue. Shaftesbury conceives the core notion of the goodness ofthings teleologically: something is good if it contributes to thewell-being or furtherance of the system of which it is a part.Individual animals are members of species, and therefore they are goodas such insofar as they contribute to the well-being of the species ofwhich they are a part. Thus, the good of things, including humanbeings, for Shaftesbury as for Clarke, is an objective quality that isknowable through reason. However, though we can know what is goodthrough reason, Shaftesbury maintains that reason alone is notsufficient to motivate human action. Shaftesbury articulates thestructure of a distinctively human moral sensibility. Moralsensibility depends on the faculty of reflection. When we reflect onfirst-order passions such as gratitude, kindness and pity, we findourselves approving or liking them and disapproving or disliking theiropposites. By virtue of our receptivity to such feelings, we arecapable of virtue and have a sense of right and wrong. In this way,Shaftesbury defines the moral sense that plays a significant role inthe theories of subsequent Enlightenment thinkers such as FrancisHutcheson and David Hume.

In the rationalist tradition, the conflict within the breast of theperson between the requirements of morality and self-interest iscanonically a conflict between the person’s reason and herpassions. Shaftesbury’s identification of a moral sentiment inthe nature of humanity renders this a conflict within sensibilityitself, a conflict between different sentiments, between aself-interested sentiment and an unegoistic sentiment. Though bothShaftesbury and Hutcheson, no less than Clarke, oppose Hobbes’segoism, it is nonetheless true that the doctrine of moral sensibilitysoftens moral demands, so to speak. Doing what is morally right ormorally good is intrinsically bound up with a distinctive kind ofpleasure on their accounts. It is significant that both Shaftesburyand Hutcheson, the two founders of modern moral sense theory,articulate their ethical theory in conjunction with an aesthetictheory. Arguably the pleasure we feel in the apprehension of somethingbeautiful isdisinterested pleasure. Our susceptibility toaesthetic pleasure can be taken to reveal that we apprehend andrespond to objective (or, anyway, universal) values, not only ornecessarily on the basis of reason, but through our naturalsensibility instead. Thus, aesthetics, as Shaftesbury and Hutchesonindependently develop an account of it, gives encouragement to theirdoctrines of moral sensibility. But an account of moral virtue, unlikeaesthetics, requires an account of moralmotivation. As notedabove, both Shaftesbury and Hutcheson want to do justice to the ideathat proper moral motivation is not the pursuit of pleasure, evendisinterested pleasure, but rather an immediate response to theperception of moral value. The problem of giving a satisfying accountof moral motivation is a difficult one for empiricist moralphilosophers in the Enlightenment.

While for Shaftesbury, at the beginning of the moral sense tradition,moral sense tracks a mind-independent order of value, David Hume,motivated in part by a more radical empiricism, is happy to let theobjective order go. We have no access through reason to an independentorder of value which moral sense would track. For Hume, morality isfounded completely on our sentiments. Hume is often regarded as themain originator of so-called “ethical subjectivism”,according to which moral judgments or evaluations (regarding actionsor character) do not make claims about independent facts but merelyexpress the subject’s feelings or attitudes with respect toactions or character. Such subjectivism is relieved of the difficulttask of explaining how the objective order of values belongs to thenatural world as it is being reconceived by natural science in theperiod; however, it faces the challenge of explaining how error anddisagreement in moral judgments and evaluations are possible.Hume’s account of the standards of moral judgment follows thatof Hutcheson in relying centrally on the “natural”responses of an ideal observer or spectator.

Hume’s ethics is exemplary of philosophical ethics in theEnlightenment by virtue of its belonging to the attempt to provide anew, empirically grounded science of human nature, free of theologicalpresuppositions. As noted above, the attempts by the members of theFrench Enlightenment to present a new understanding of human natureare strongly influenced by Locke’s “sensationalism”,which, radicalized by Condillac, amounts to the attempt to base allcontents and faculties of the human mind on the senses. Typically, theFrenchphilosophes draw more radical or iconoclasticimplications from the new “science of man” than English orScottish Enlightenment figures. Claude-Adrien Helvétius(1715–1771) is typical here. InDel’ésprit (1758), Helvétius follows theLockean sensationalism of Condillac and pairs it with the claim thathuman beings are motivated in their actions only by the natural desireto maximize their own pleasure and minimize their pain.Del’ésprit, though widely read, gives rise to strongnegative reactions in the time, both by political and religiousauthorities (the Sorbonne, the Pope and the Parlement of Paris allcondemn the book) and by prominent fellowphilosophes, ingreat part because Helvétius’s psychology seems tocritics to render moral imperatives and values without basis, despitehis best attempts to derive them. Helvétius attempts to groundthe moral equality of all human beings by portraying all human beings,whatever their standing in the social hierarchy, whatever theirspecial talents and gifts, as equally products of the nature we shareplus the variable influences of education and social environment. But,to critics, Helvétius’s account portrays all human beingsas equal only by virtue of portraying all as equally worthless(insofar as the claim to equality is grounded on all being equallydetermined by external factors). However, Helvétius’sideas, inDe l’ésprit as well as in itsposthumously published sequelDe l’homme (1772), exerta great deal of influence, especially his case for the role ofpleasure and pain in human motivation and the role of education andsocial incentives in shaping individuals into contributors to thesocial good. Helvétius is sometimes regarded as the father ofmodern utilitarianism through his articulation of the greatesthappiness principle and through his influence on Bentham.

Helvétius is typical in the respect that he is radical in therevisions he proposes, not in common moral judgments or customs of thetime, but rather regarding the philosophical grounding of thosejudgments and customs. But there are some philosophers in theEnlightenment who are radical in the revisions they propose regardingthe content of ethical judgments themselves. The Marquis de Sade ismerely the most notorious example, among a set of Enlightenmentfigures (including also the Marquis de Argens and Diderot himself insome of his writings) who, within the context of the new naturalismand its emphasis on the pursuit of pleasure, celebrate the avidpursuit of sexual pleasure and explicitly challenge the sexual mores,as well as the wider morality, of their time. The more or lessfictionalized, philosophically self-conscious “libertine”is one significant expression of Enlightenment ethical thought.

If the French Enlightenment tends to advance this-worldly happiness asthe highest good for human beings more insistently than theEnlightenment elsewhere, then Rousseau’s voice is, in this as inother respects, a discordant voice in that context. Rousseau advancesthe cultivation and realization ofhuman freedom as thehighest end for human beings and thereby gives expression to anotherside of Enlightenment ethics. As Rousseau describes it, the capacityfor individual self-determination puts us in a problematic relation toour natural desires and inclinations and to the realm of naturegenerally, insofar as that realm is constituted by mechanisticcausation. Though Rousseau places a great deal of emphasis on humanfreedom, and makes significant contributions to our understanding ofourselves as free, he does not address very seriously the problem ofthe place of human freedom in the cosmos as it is conceived within thecontext of Enlightenment naturalism.

However, Rousseau’s writings help Kant to the articulation of apractical philosophy that addresses many of the tensions in theEnlightenment. Kant follows Rousseau, and disagrees with empiricism inethics in the period, in emphasizing human freedom, rather than humanhappiness, as the central orienting concept of practical philosophy.Though Kant presents the moral principle as a principle of practicalreason, his ethics also disagrees significantly with rationalistethics in the period. According to Kant, rationalists such as Wolff,insofar as they take moral prescriptions to follow from an end givento the will (in Wolff’s case, the end of perfection), do notunderstand us as autonomous in our moral activity. Throughinterpreting the faculty of the will itself as practical reason, Kantunderstands the moral principle as internally legislated, thus as notonly compatible with freedom, but as equivalent to the principle of afree will, as a principle of autonomy. As noted above, rationalists inethics in the period are challenged to explain how the objective moralorder which reason in us allegedly discerns gives rise to validprescriptions binding on our wills (the gap betweenis andought). For Kant, the moral order is not independent of ourwill, but rather represents the formal constraints of willing as such.Kant’s account thus both avoids the is-ought gap and interpretsmoral willing as expressive of our freedom.

Moreover, by virtue of his interpretation of the moral principle asthe principle of pure practical reason, Kant is able to redeem theordinary sense of moral requirements as over-riding, as potentiallyopposed to the claims of one’s happiness, and thus as differentin kind from the deliverances of prudential reasoning. This ordinarysense of moral requirements is not easily accommodated within thecontext of Enlightenment empiricism and naturalism. Kant’s starkdichotomy between a person’s practical reason and her sensiblenature is strongly criticized, both by the subsequent Romanticgeneration and in the contemporary context; but this dichotomy isbound up with an important benefit of Kant’s view – muchpromoted by Kant himself – within the context of theEnlightenment. Elaborated in the context of Kant’s idealism as acontrast between the “realm of freedom” and the“realm of nature”, the dichotomy enables Kant’sproposed solution to the conflict between freedom and nature thatbesets Enlightenment thought. As noted above, Kant argues that theapplication of the causal principle is restricted to the realm ofnature, thus making room for freedom, compatibly with the causaldetermination of natural events required by scientific knowledge.Additionally, Kant attempts to show that morality “leadsineluctably to” religious belief (in the supersensible objectsof God and of the immortal soul) while being essentially not foundedon religious belief, thus again vindicating the ordinary understandingof morality while still furthering Enlightenment values andcommitments.

2.3 Religion and the Enlightenment

Though the Enlightenment is sometimes represented as the enemy ofreligion, it is more accurate to see it as critically directed againstvarious (arguably contingent) features of religion, such assuperstition, enthusiasm, fanaticism and supernaturalism. Indeed theeffort to discern and advocate for a religion purified of suchfeatures – a “rational” or “natural”religion – is more typical of the Enlightenment than oppositionto religion as such. Even Voltaire, who is perhaps the mostpersistent, powerful, vocal Enlightenment critic of religion, directshis polemic mostly against the Catholic Church in France –“l’infâme” in his famous sign-off inhis letters, “Écrasezl’infâme” (“Crush the infamous”)refers to the Church, not to religion as such. However, controversyregarding the truth-value or reasonableness of religious belief ingeneral, Christian belief in particular, and controversy regarding theproper place of religion in society, occupies a particularly centralplace in the Enlightenment. It’s as if the terrible, violentconfessional strife in the early modern period in Europe, the bloodydrawn-out wars between the Christian sects, was removed to theintellectual arena in the Enlightenment and became a set of moregeneral philosophical controversies.

Alongside the rise of the new science, the rise of Protestantism inwestern Christianity also plays an important role in generating theEnlightenment. The original Protestants assert a sort of individualliberty with respect to questions of faith against the paternalisticauthority of the Church. The “liberty of conscience”, soimportant to Enlightenment thinkers in general, and asserted againstall manner of paternalistic authorities (including Protestant),descends from this Protestant assertion. The original Protestantassertion initiates a crisis of authority regarding religious belief,a crisis of authority that, expanded and generalized and even, to someextent, secularized, becomes a central characteristic of theEnlightenment spirit. The original Protestant assertion against theCatholic Church bases itself upon the authority of scripture. However,in the Enlightenment, the authority of scripture is stronglychallenged, especially when taken literally. Developing naturalscience renders acceptance of a literal version of the Bibleincreasingly untenable. But authors such as Spinoza (in hisTractatus Theologico-Politicus) present ways of interpretingscripture according to its spirit, rather than its letter, in order topreserve its authority and truth, thus contributing to theEnlightenment controversy of whether some rationally purified versionof the religion handed down in the culture belongs to the truephilosophical representation of the world or not; and, if so, what itscontent is.

It is convenient to discuss religion in the Enlightenment bypresenting four characteristic forms of Enlightenment religion inturn: deism, religion of the heart, fideism and atheism.

Deism. Deism is the form of religion most associated with theEnlightenment. According to deism, we can know by the natural light ofreason that the universe is created and governed by a supremeintelligence; however, although this supreme being has a plan forcreation from the beginning, the being does not interfere withcreation; the deist typically rejects miracles and reliance on specialrevelation as a source of religious doctrine and belief, in favor ofthe natural light of reason. Thus, a deist typically rejects thedivinity of Christ, as repugnant to reason; the deist typicallydemotes the figure of Jesus from agent of miraculous redemption toextraordinary moral teacher. Deism is the form of religion fitted tothe new discoveries in natural science, according to which the cosmosdisplays an intricate machine-like order; the deists suppose that thesupposition of God is necessary as the source or author of this order.Though not a deist himself, Isaac Newton provides fuel for deism withhis argument in hisOpticks (1704) that we must infer fromthe order and beauty in the world to the existence of an intelligentsupreme being as the cause of this order and beauty. Samuel Clarke,perhaps the most important proponent and popularizer of Newtonianphilosophy in the early eighteenth century, supplies some of the moredeveloped arguments for the position that the correct exercise ofunaided human reason leads inevitably to the well-grounded belief inGod. He argues that the Newtonian physical system implies theexistence of a transcendent cause, the creator God. In his first setof Boyle lectures,A Demonstration of the Being and Attributes ofGod (1705), Clarke presents the metaphysical or “argumenta priori” for God’s existence. This argumentconcludes from the rationalist principle that whatever exists musthave a sufficient reason or cause of its existence to the existence ofa transcendent, necessary being who stands as the cause of the chainof natural causes and effects. Clarke also supports the empiricalargument from design, the argument that concludes from the evidence oforder in nature to the existence of an intelligent author of thatorder. In his second set of Boyle lectures,A Discourse Concerningthe Unchangeable Obligations of Natural Religion (1706), Clarkeargues as well that the moral order revealed to us by our naturalreason requires the existence of a divine legislator and an afterlife,in which the supreme being rewards virtue and punishes vice. In hisBoyle lectures, Clarke argues directly against the deist philosophyand maintains that what he regards as the one true religion,Christianity, is known as such on the basis of miracles and specialrevelation; still, Clarke’s arguments on the topic of naturalreligion are some of the best and most widely-known arguments in theperiod for the general deist position that natural philosophy in abroad sense grounds central doctrines of a universal religion.

Enlightenment deism first arises in England. InOn theReasonableness of Christianity (1695), Locke aims to establishthe compatibility of reason and the teachings of Christianity. ThoughLocke himself is (like Newton, like Clarke) not a deist, the majorEnglish deists who follow (John Toland,Christianity NotMysterious [1696]); Anthony Collins,A Discourse ofFreethinking [1713]; Matthew Tindal,Christianity as Old asCreation [1730]) are influenced by Locke’s work. Voltairecarries deism across the channel to France and advocates for it thereover his long literary career. Toward the end-stage, the farcicalstage, of the French Revolution, Robespierre institutes a form ofdeism, the so-called “Cult of the Supreme Being”, as theofficial religion of the French state. Deism plays a role in thefounding of the American republic as well. Many of the foundingfathers (Jefferson, Franklin, Madison, Paine) author statements ortracts that are sympathetic to deism; and their deistic sympathiesinfluence the place given (or not given) to religion in the newAmerican state that they found.

Religion of the Heart. Opposition to deism derives sometimesfrom the perception of it as coldly rationalistic. The God of thedeists, arrived at through a priori or empirical argument and referredto as the Prime Mover or Original Architect, is often perceived asdistant and unconcerned with the daily struggles of human existence,and thus as not answering the human needs from which religion springsin the first place. Some important thinkers of the Enlightenment– notably Shaftesbury and Rousseau – present religion asfounded on natural human sentiments, rather than on the operations ofthe intellect. Rousseau has his Savoyard Vicar declare, in hisProfession of Faith inEmile (1762), that the idea ofworshiping a beneficent deity arose in him initially as he reflectedon his own situation in nature and his “heart began to glow witha sense of gratitude towards the author of our being”. TheSavoyard Vicar continues: “I adore the supreme power, and meltinto tenderness at his goodness. I have no need to be taughtartificial forms of worship; the dictates of nature are sufficient. Isit not a natural consequence of self-love to honor those who protectus, and to love such as do us good?” This “natural”religion – opposed to the “artificial” religionsenforced in the institutions – is often classed as a form ofdeism. But it deserves separate mention, because of its grounding innatural human sentiments, rather than in reason or in metaphysical ornatural scientific problems of cosmology.

Fideism. Deism or natural religion of various sorts tends torely on the claim that reason or human experience supports thehypothesis that there is a supreme being who created or authored theworld. In one of the most important philosophical texts on naturalreligion to appear during the Enlightenment, David Hume’sDialogues Concerning Natural Religion (published posthumouslyin 1779), this supposition is criticized relentlessly, incisively andin detail. Naturally, the critical, questioning attitudecharacteristic of the Enlightenment in general is directed against thearguments on which natural religion is based. In Part Nine of theDialogues, Samuel Clarke’s “argument apriori” (as defended by the character Demea) is dispatchedfairly quickly, but with a battery of arguments. But Hume is mainlyconcerned in theDialogues with the other major pillar ofnatural religion in the Enlightenment, the “empirical”argument, the teleological argument or the argument from design.Cleanthes, the character who advances the design argument in thedialogue, proceeds from the rule for empirical reasoning that likeeffects prove like causes. He reasons that, given the resemblancebetween nature, which displays in many respects a “curiousadaptation of means to ends”, and a man-made machine, we mustinfer the cause of nature to be an intelligence like ours, thoughgreater in proportion as nature surpasses in perfection the productsof human intelligence. Philo, the skeptical voice in theDialogues, presses Cleanthes’ argument on many fronts.He points out that the argument is only as strong as the similaritybetween nature or parts of nature and man-made machines, and further,that a close scrutiny reveals that analogy to be weak. Moreover,according to the principle of the argument, the stronger the evidencefor an author (or authors) of nature, themore like us thatauthor (or authors) should be taken to be. Consequently, according toPhilo, the argument does not support the conclusion thatGodexists, taking God to be unitary, infinite, perfect, et cetera. Also,although the existence of evil and disorder in nature may serveactually to strengthen the case for the argument, given the disorderin human creations as well, the notion that God authors evil anddisorder is disturbing. If one denies that there is disorder and evilin nature, however implausibly, the effect is to emphasize again thedissimilarity between nature and human products and thus weaken thecentral basis of the argument. With these and other considerations,Philo puts the proponent of the empirical argument in a difficultdialectical position. But Cleanthes is not moved. He holds theinference from the phenomenon of the curious adaptation of means toends in nature to the existence of an intelligent and beneficentauthor to be so natural as to be impervious to the philosophicalcavils raised by Philo. And, in the ambiguous conclusion of the work,Philo seems to agree. Though Hume himself seems to have been anatheist, one natural way to take the upshot of hisDialoguesis that religious belief is so “natural” to us thatrational criticism cannot unseat it. The ambiguous upshot of the workcan be taken to be the impotence of rational criticism in the face ofreligious belief, rather than the illegitimacy of religious belief inthe face of rational criticism. This tends toward fideism, the viewaccording to which religious faith maintains its truth over againstphilosophical reasoning, which opposes but cannot defeat it. Fideismis most often associated with thinkers whose beliefs run contrary tothe trends of the Enlightenment (Blaise Pascal, Johann-Georg Hamann,Søren Kierkegaard), but the skeptical strain in theEnlightenment, from Pierre Bayle through David Hume, expresses itselfnot only in atheism, but also in fideism.

Atheism. Atheism is more present in the French Enlightenmentthan elsewhere. In the writings of Denis Diderot, atheism is partlysupported by an expansive, dynamic conception of nature. According tothe viewpoint developed by Diderot, we ought to search for theprinciples of natural order within natural processes themselves, notin a supernatural being. Even if we don’t yet know the internalprinciples for the ordering and development of natural forms, theappeal to a transcendent author of such things is reminiscent, toDiderot’s ear, of the appeal to Aristotelian “substantialforms” that was expressly rejected at the beginning of modernscience as explaining nothing. The appeal to a transcendent authordoes not extend our understanding, but merely marks and fixes thelimits of it. Atheism (combined with materialism) in the FrenchEnlightenment is perhaps most identified with the Barond’Holbach, whoseSystem of Nature (1770) generated agreat deal of controversy at the time for urging the case for atheismexplicitly and emphatically. D’Holbach’s system of natureis strongly influenced by Diderot’s writings, though it displaysless subtlety and dialectical sophistication. Though mostEnlightenment thinkers hold that morality requires religion, in thesense that morality requires belief in a transcendent law-giver and inan after-life, d’Holbach (influenced in this respect by Spinoza,among others) makes the case for an ethical naturalism, an ethics thatis free of any reference to a supernatural grounding or aspiration.Like Helvétius before him, d’Holbach presents an ethicsin which virtue consists in enlightened self-interest. Themetaphysical background of the ethics he presents is deterministicmaterialism. The Prussian enlightened despot, Frederick the Great,famously criticizes d’Holbach’s book for exemplifying theincoherence that troubles the Enlightenment generally: whiled’Holbach provides passionate moral critiques of existingreligious and social and political institutions and practices, his ownmaterialist, determinist conception of nature allows no place formoral “oughts” and prescriptions and values.

3. The Beautiful: Aesthetics in the Enlightenment

Modern systematic philosophical aesthetics not only first emerges inthe context of the Enlightenment, but also flowers brilliantly there.As Ernst Cassirer notes, the eighteenth century not only thinks ofitself as the “century of philosophy”, but also as“the age of criticism,” where criticism is centrally(though not only) art and literary criticism (Cassirer 1932, 255).Philosophical aesthetics flourishes in the period because of itsstrong affinities with the tendencies of the age. AlexanderBaumgarten, the German philosopher in the school of Christian Wolff,founds systematic aesthetics in the period, in part through giving itits name. “Aesthetics” is derived from the Greek word for“senses”, because for Baumgarten a science of thebeautiful would be a science of the sensible, a science of sensiblecognition. The Enlightenment in general re-discovers the value of thesenses, not only in cognition, but in human lives in general, and so,given the intimate connection between beauty and human sensibility,the Enlightenment is naturally particularly interested in aesthetics.Also, the Enlightenment includes a general recovery and affirmation ofthe value of pleasure in human lives, against the tradition ofChristian asceticism, and the flourishing of the arts, of thecriticism of the arts and of the philosophical theorizing aboutbeauty, promotes and is promoted by this recovery and affirmation. TheEnlightenment also enthusiastically embraces the discovery anddisclosure of rational order in nature, as manifest most clearly inthe development of the new science. It seems to many theorists in theEnlightenment that the faculty of taste, the faculty by which wediscern beauty, reveals to us some part of this order, a distinctiveharmony, unities amidst variety. Thus, in the phenomenon of aestheticpleasure, human sensibility discloses to us rational order, thusbinding together two enthusiasms of the Enlightenment.

3.1 French Classicism and German Rationalism

In the early Enlightenment, especially in France, the emphasis is uponthe discernment of an objective rational order, rather than upon thesubject’s sensual aesthetic pleasure. Though Descartes’philosophical system does not include a theory of taste or of beauty,his mathematical model of the physical universe inspires theaesthetics of French classicism. French classicism begins from theclassical maxim that the beautiful is the true. Nicolas Boileau writesin his influential didactic poem,The Art of Poetry (1674),in which he lays down rules for good versification within differentgenres, that “Nothing is beautiful but the true, the true aloneis lovable.” In the period the true is conceived of as anobjective rational order. According to the classical conception of artthat dominates in the period, artimitates nature, though notnature as given in disordered experience, but theidealnature, the ideal in which we can discern and enjoy “unity inmultiplicity.” In French classicism, aesthetics is very muchunder the influence of, and indeed modeled on, systematic, rigoroustheoretical science of nature. Just as in Descartes’ model ofscience, where knowledge of all particulars depends on prior knowledgeof the principle from which the particulars are deduced, so also inthe aesthetics of French classicism, the demand is for systematizationunder a single, universal principle. The subjection of artisticphenomena to universal rules and principles is expressed, for example,in the title of Charles Batteaux’s main work,The Fine ArtsReduced to a Single Principle (1746), as well as inBoileau’s rules for good versification.

In Germany in the eighteenth century, Christian Wolff’ssystematic rationalist metaphysics forms the basis for much of thereflection on aesthetics, though sometimes as a set of doctrines to beargued against. Wolff affirms the classical dictum that beauty istruth; beauty is truth perceived through the feeling of pleasure.Wolff understands beauty to consist in the perfection in things, whichhe understands in turn to consist in a harmony or order of a manifold.We judge something beautiful through a feeling of pleasure when wesense in it this harmony or perfection. Beauty is, for Wolff, thesensitive cognition of perfection. Thus, for Wolff, beauty correspondsto objective features of the world, but judgments of beauty arerelative to us also, insofar as they are based on the human faculty ofsensibility.

3.2 Empiricism and Subjectivism

Though philosophical rationalism forms the basis of aesthetics in theearly Enlightenment in France and Germany, thinkers in the empiricisttradition in England and Scotland introduce many of the salient themesof Enlightenment aesthetics. In particular, with the rise ofempiricism and subjectivism in this domain, attention shifts to theground and nature of the subject’s experience of beauty, thesubject’s aesthetic response. Lord Shaftesbury, though nothimself an empiricist or subjectivist in aesthetics, makes significantcontributions to this development. Shaftesbury re-iterates theclassical equation, “all beauty is truth,” but the truththat beauty is for Shaftesbury is not an objective rational order thatcould also be known conceptually. Though beauty is, for Shaftesbury, akind of harmony that is independent of the human mind, under theinfluence of Plotinus, he understands the human being’simmediate intuition of the beautiful as a kind of participation in theoriginal harmony. Shaftesbury focuses attention on the nature of thesubject’s response to beauty, as elevating the person, alsomorally. He maintains that aesthetic response consists in adisinterested unegoistic pleasure; the discovery of thiscapacity for disinterested pleasure in harmony shows the way for thedevelopment of his ethics that has a similar grounding. And, in fact,in seeing aesthetic response as elevating oneself aboveself-interested pursuits, through cultivating one’s receptivityto disinterested pleasure, Shaftesbury ties tightly togetheraesthetics and ethics, morality and beauty, and in that respect alsocontributes to a trend of the period. Also, in placing the emphasis onthe subject’s response to beauty, rather than on the objectivecharacteristics of the beautiful, Shaftesbury makes aesthetics belongto the general Enlightenment interest in human nature. Thinkers of theperiod find in our receptivity to beauty a key both to understandingboth distinctively human nature and its perfection.

Francis Hutcheson follows Shaftesbury in his emphasis on thesubject’s aesthetic response, on the distinctive sort ofpleasure that the beautiful elicits in us. Partly because theNeo-Platonic influence, so pronounced in Shaftesbury’saesthetics, is washed out of Hutcheson’s, to be replaced by amore thorough-going empiricism, Hutcheson understands this distinctiveaesthetic pleasure as more akin to a secondary quality. Thus,Hutcheson’s aesthetic work raises the prominent question whether“beauty” refers to something objective at all or whetherbeauty is “nothing more” than a human idea or experience.As in the domain of Enlightenment ethics, so with Enlightenmentaesthetics too, the step from Shaftesbury to Hutcheson marks a steptoward subjectivism. Hutcheson writes in one of hisTwoTreatises, hisInquiry Concerning Beauty, Order, Harmony,Design (1725) that “the word ‘beauty’ is takenfor theidea raised in us, and asense of beauty forour power of receiving this idea” (Section I, ArticleIX). However, though Hutcheson understands beauty to be an idea in us,he takes this idea to be “excited” or“occasioned” in us by distinctive objective qualities, inparticular by objects that display “uniformity amidstvariety” (ibid., Section II, Article III). In the verytitle of Hutcheson’s work above, we see the importance of theclassical ideas of (rational) order and harmony in Hutcheson’saesthetic theory, even as he sets the tenor for much Enlightenmentdiscussion of aesthetics through placing the emphasis on thesubjective idea and aesthetic response.

David Hume’s famous essay on “the standard of taste”raises and addresses the epistemological problem raised bysubjectivism in aesthetics. If beauty is an idea in us, rather than afeature of objects independent of us, then how do we understand thepossibility of correctness and incorrectness – how do weunderstand the possibility of standards of judgment – in thisdomain? The problem is posed more clearly for Hume because heintensifies Hutcheson’s subjectivism. He writes in theTreatise that “pleasure and pain….are not onlynecessary attendants of beauty and deformity, but constitute theirvery essence” (Treatise, Book II, part I, sectionviii). But if a judgment of taste is based on, or expresses,subjective sentiments, how can it be incorrect? In his response tothis question, Hume accounts for the expectation of agreement injudgments of taste by appealing to the fact that we share a commonhuman nature, and he accounts for ‘objectivity’ orexpertise in judgments of taste, within the context of hissubjectivism, by appealing to the normative responses of well-placedobservers. Both of these points (the commonality of human nature andthe securing of ‘objectivity’ in judgments based onsentiments by appeal to the normative responses of appropriatelyplaced observers) are typical of the period more generally, andespecially of the strong empiricist strain in the Enlightenment. Humedevelops the empiricist line in aesthetics to the point where littleremains of the classical emphasis on the order or harmony or truththat is, according to the French classicists, apprehended andappreciated in our aesthetic responses to the beautiful, and thus,according to the classicists, the ground of aesthetic responses.

3.3 Late Enlightenment Aesthetics

Immanuel Kant faces squarely the problem of the normativity ofjudgments of taste. Influenced by Hutcheson and the British empiricisttradition in general, Kant understands judgments of taste to befounded on a distinctive sort of feeling, adisinterestedpleasure. In taking judgments of taste to be subjective (they arefounded on the subject’s feeling of pleasure) and non-cognitive(such judgments do not subsume representations under concepts and thusdo not ascribe properties to objects), Kant breaks with the Germanrationalist school. However Kant continues to maintain that judgmentsof beauty are like cognitive judgments in making a legitimate claim touniversal agreement – in contrast to judgments of the agreeable.The question is how to vindicate the legitimacy of this demand. Kantargues that the distinctive pleasure underlying judgments of taste isthe experience of the harmony of the faculties of the imagination andthe understanding, a harmony that arises through their “freeplay” in the process of cognizing objects on the basis of givensensible intuition. The harmony is “free” in an experienceof beauty in the sense that it is not forced by rules of theunderstanding, as is the agreement among the faculties in acts ofcognition. The order and harmony that we experience in the face of thebeautiful is subjective, according to Kant; but it is at the same timeuniversal and normative, by virtue of its relation to the conditionsof human cognition.

The emphasis Kant places on the role of the activity of theimagination in aesthetic pleasure and discernment typifies a trend inEnlightenment thought. Whereas early in the Enlightenment, in Frenchclassicism, and to some extent in Christian Wolff and other figures ofGerman rationalism, the emphasis is on the more-or-less staticrational order and proportion and on rigid universal rules or laws ofreason, the trend during the development of Enlightenment aestheticsis toward emphasis on theplay of the imagination and itsfecundity in generating associations.

Denis Diderot is an important and influential author on aesthetics. Hewrote the entry “On the Origin and Nature of theBeautiful” for theEncyclopedia (1752). Like Lessing inGermany, Diderot not only philosophized about art and beauty, but alsowrote plays and influential art criticism. Diderot is stronglyinfluenced in his writings on aesthetics by the empiricism in Englandand Scotland, but his writing is not limited to that standpoint.Diderot repeats the classical dictum that art should imitate nature,but, whereas, for French classicists, the nature that art shouldimitate isideal nature – a static, universal rationalorder – for Diderot, nature is dynamic and productive. ForDiderot, the nature the artist ought to imitate is therealnature we experience, warts and all (as it were). The particularismand realism of Diderot’s aesthetics is based on a critique ofthe standpoint of French classicism (see Cassirer 1935, p. 295f.).This critique exposes the artistic rules represented by Frenchclassicists as universal rules of reason as nothing more thanconventions marking what is consideredproper withina certain tradition. In other words, the prescriptions within theFrench classical tradition areartificial, notnatural, and constitute fetters to artistic genius. Diderottakes liberation from such fetters to come from turning to the task ofobserving and imitatingactual nature. Diderot’semphasis on the primeval productive power and abundance of nature inhis aesthetic writings contributes to the trend toward focus onartistic creation and expression (as opposed to artistic appreciationand discernment) that is a characteristic of the late Enlightenmentand the transition to Romanticism.

Lessing’s aesthetic writings play an important role in elevatingthe aesthetic category of expressiveness. In his famousLaocoön: An Essay on the Limits of Painting and Poetry(1766), Lessing argues, by comparing the famous Greek statue with therepresentation of Laocoön’s suffering in Virgil’spoetry, that the aims of poetry and of the visual arts are notidentical; he argues that the aim of poetry is not beauty, butexpression. In elevating the aesthetic category of expressiveness,Lessing challenges the notion that all art is imitation of nature. Hisargument also challenges the notion that all the various arts can bededuced from a single principle. Lessing’s argument inLaocoön supports the contrary thesis that the distinctarts have distinct aims and methods, and that each should beunderstood on its own terms, not in terms of an abstract generalprinciple from which all arts are to be deduced. For some, especiallyfor critics of the Enlightenment, in this point Lessing is alreadybeyond the Enlightenment. Certainly it is true that the emphasis onthe individual or particular, over against the universal, which onefinds in other late Enlightenment thinkers, is in tension withEnlightenment tenets. Herder (following Hamann to some extent) arguesthat each individual artobject has to be understood in itsown terms, as a totality complete unto itself. With Herder’sstark emphasis on individuality in aesthetics, over againstuniversality, the supplanting of the Enlightenment with Romanticismand Historicism is well advanced. But, according to the point of viewtaken in this entry, the conception of the Enlightenment according towhich it is distinguished by its prioritization of the order ofabstract, universal laws and principles, over against concreteparticulars and the differences amongst them, is too narrow; it failsto account for much of the characteristic richness in the thought ofthe period. Indeed aesthetics itself, as a discipline, which, asnoted, is founded in the Enlightenment by the German rationalist,Alexander Baumgarten, owes its existence to the tendency in theEnlightenment to search for and discover distinct laws for distinctkinds of phenomena (as opposed to insisting that all phenomena be madeintelligible through the same set of general laws and principles).Baumgarten founds aesthetics as a ‘science’ through theattempt to establish the sensible domain as cognizable in a waydifferent from that which prevails in metaphysics. Aesthetics inGermany in the eighteenth century, from Wolff to Herder, both typifiesmany of the trends of the Enlightenment and marks the field where theEnlightenment yields to competing worldviews.

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Acknowledgments

Mark Alznauer, Margaret Atherton, Kyla Ebels-Duggan, Alan Nelson,Julius Sensat and Rachel Zuckert provided helpful comments on anearlier draft, which lead to substantial revisions.