Kant’s Copernican revolutionDaniel BonevacImmanuel Kant’s Critique of Pure Reason was to transform thephilosophical world, at once bringing the Enlightenment to its highestintellectual development and establishing a new set of problems that woulddominate philosophy in the nineteenth century and beyond. As RichardRorty has observed, Kant would turn philosophy into a profession, if for noother reason than that, after 1781, one could not be called a philosopherwithout having mastered Kant’s first Critique—which, in the words ofKant’s famous commentator, Norman Kemp Smith, “is more obscure anddifficult than even a metaphysical treatise has any right to be.”1The Critique’s central character is “Human reason,” which, Kantbegins his first edition’s preface by noting,has this peculiar fate that in one species of its knowledge it isburdened by questions which, as prescribed by the very nature ofreason itself, it is not able to ignore, but which, as transcending allits powers, it is also not able to answer.(A vii)2Reason develops principles to deal with experience; within the realm ofexperience, those principles are well justified. Reason finds itself driven,however, to ask questions extending beyond that realm. The veryprinciples it has developed and upon which it properly continues to rely indealing with experience there lead it “into darkness and contradictions”(A viii). Metaphysics, once Queen of the Sciences, now surveys thebattlefield on which these principles clash and mourns. Kant’s aim in theCritique is to rescue metaphysics, “to secure for human reason completesatisfaction” (A 856, B 884) by defining its proper sphere of application.Kant’s means for achieving this end is the critical method. The title ofthe work is ambiguous in both English and German: Pure reason may bethe agent or the object of the critique.3 In fact, it is surely both. Thecritical method requires reason to critique itself, to determine its ownlimits, and then to devise rules for staying within them.This, Kant thinks,is the key to reason’s “complete satisfaction”: “there is not a singlemetaphysical problem which has not been solved, or for the solution ofwhich the key at least has not been supplied” (A xiii).Understood in this way, Kant’s critical method hardly seemsrevolutionary. It had been exemplified already in Locke’s Essay concerningHuman Understanding and Hume’s Treatise of Human Nature. Both wereattempts to define the limits of human knowledge by employing reason ina reflective act of self-criticism. Kant’s most important contribution is notthe general idea of the critical method, but the specific form that methodtakes, for which he often uses the adjective transcendental rather thancritical. Kant claims that he uses the transcendental method andestablishes the truth of transcendental idealism.What, then, is the transcendental method? To understand it, we need tofocus on what, in the preface to the second edition of 1787, Kantconsiders the key to his advance: his Copernican revolution in philosophy.“[T]he procedure of metaphysics,” Kant writes, “has hitherto been amerely random groping, and, what is worst of all, a groping among mereconcepts” (B xv). Kant finds himself capable of setting metaphysics uponthe secure path of a science by advancing a hypothesis analogous to thatof Copernicus.Hitherto it has been assumed that all our knowledge must conformto objects. But all attempts to extend our knowledge of objects byestablishing something in regard to them a priori, by means ofconcepts, have, on this assumption, ended in failure. We musttherefore make trial whether we may not have more success in thetasks of metaphysics, if we suppose that objects must conform to ourknowledge.(B xvi)Copernicus explained the motions of the heavenly bodies as resulting,not just from their own motion, but also from the motion of theobservers on earth. Just as he sought “the observed movements, not inthe heavenly bodies, but in the spectator” (B xxii n.), so Kant seeks thelaws governing the realm of experience not in the objects themselves butin us: “we can know a priori of things only what we ourselves put intothem” (B xviii).THE PLATONIC HERITAGEKant is a rationalist. We might define a concept rationalist as one whobelieves in innate concepts—that is, that we have first-order cognitiveabilities that we do not derive from experience—and a judgmentrationalist as one who believes that we can know some synthetic truths apriori that is, that we can know independently of experience some truthsthat are not merely linguistic or verbal, that are not automatically true orfalse because of the meanings of the words that constitute them. Kant isplainly a rationalist in both senses. He argues that we can deduce pureconcepts of the understanding a priori, independently of experience, fromthe mere possibility of experience, and moreover that there are synthetic apriori truths—that is, truths that we can know independently ofexperience but that are not merely verbal. Indeed, the establishment ofrationalism in both senses seems to be a major goal of the Critique.Like many rationalists, Kant understands himself as working within thePlatonic tradition. The central problems he attacks and his solutions tothem stem directly from that tradition. To understand Kant’s Copernicanrevolution, therefore, we must consider the framework in which histhought is embedded.Consider a judgment of perception, for example, (said pointing to afigure drawn on a blackboard) ‘This is a triangle.’ According to Plato, atone very influential stage of his thought, at least, the mind so judging isJanus-faced. It is turned toward a perceptual object, a triangle, if it judgescorrectly. It is also turned toward the abstract form of a triangle. Both theobject and the form have real causal or explanatory power. The object iscausally responsible for our perception of it. But we are able to perceive itas a triangle because we apprehend the general form of triangularity. Theform of a triangle is exemplified in the triangle itself, which in turn is aninstance of, or, in Plato’s technical language, participates in, the form.The forms constitute the most distinctive feature of Plato’s philosophyof mind. They explain our ability to think general thoughts; they accountfor regularities as well as changes in experience; they explain howdifferent people (or the same person at different times) can think the samethought; and they explain how thoughts can be veridical. We may thinkgeneral thoughts, for example, by thinking about the forms and how theyrelate. Regularities in experience involve constant relations of forms;changes occur when an object of sense stops participating in one form andbegins participating in another. Two different people can think the samethought by attending to the same forms. Finally, thoughts can depictreality accurately by involving the forms that are actually instantiated.But the forms also generate a serious epistemological puzzle. Bydefinition, the forms are not themselves objects of experience; we do notperceive triangularity as we perceive individual triangles. How, then, dowe know anything about them? How is the realm of forms, which Philo ofAlexandria later termed “the intelligible world,” intelligible? In anAristotelian philosophy of mind, we generate our own general conceptsfrom experience through a process of abstraction. A Platonist may borrowthis account for certain general concepts, but cannot use it for all, becauseit is central to Platonism that some forms are ultimately responsible forour abilities to think the corresponding thoughts. On Plato’s view, we donot abstract the idea of a pure triangle from triangular objects weperceive; indeed, we never encounter a pure triangle in experience.Instead, we recognize objects as triangular because we apprehend the formof pure triangularity and recognize that the objects approximate that pureform. In this sense, the forms have causal power; we are able to think ofthings as triangular by virtue of our apprehension of the form.Unfortunately, Plato has no theory that explains our interaction withthe forms. He relies on two metaphors. In the Meno, he speaks ofrecollection; we apprehend the forms by recalling a time before birth whenour souls were united with them. In the Republic, he speaks of the form ofthe Good as analogous to the sun, shedding light on the realm of formsand making possible our apprehension of them. Neither metaphor yields asatisfactory theory within the limits of Platonic metaphysics. Neither,moreover, seems to explain our apprehension of forms without beggingthe question. The Meno metaphor explains the causal efficacy of the formsnow by appealing to their efficacy at some earlier time; the Republicmetaphor, by appealing to the efficacy of the form of the Good. TheNeoplatonic theory of emanation, according to which the entire realm offorms is ordered, with the causal efficacy of higher levels making lowerlevels possible and intelligible, does little to change the centralepistemological difficulty.Augustine, however, solves Platonism’s epistemological problem bygoing beyond the resources of the original theory. To put it crudely, headopts the Republic’s solution, but replaces the form of the Good withGod. It is not clear why the form of the Good should be more causallyefficacious than any other form. Causal efficacy, in contrast, is not aproblem for God, who can do anything. Augustine thus follows Philo inidentifying the forms with ideas in the mind of God, and describes theprocess by which we apprehend the forms as illumination, an act ofrevelation by which God allows us to make use of a portion of divinemental resources and by which, therefore, God makes our minds resemblethe divine mind. We have innate cognitive capacities that reflect theprinciples according to which God created the world.Platonism remained Augustinian throughout the medieval debatesconcerning realism and nominalism arising from the conflict betweenPlatonic and Aristotelian theories of substance and knowledge. Descartes,however, advanced a new kind of skeptical argument that forced a changein Platonism and that brought the theory of knowledge to center stage inmodern philosophy. He added to the traditional arguments of Sextus andCicero the possibility of an evil deceiver, who systematically misaligns ourminds to reality. This extends farther than traditional skeptical arguments,for it raises the possibility that not only sensible knowledge but even logicand mathematics might be mistaken. It thus challenges the Augustiniansolution to Platonism’s epistemological problem. Why should illuminationproduce veridical knowledge? Why should we believe that God reveals theportion of the divine mind relevant to the construction of the world, andnot some counterfeit of it? Why should our innate ideas, and the a prioriknowledge arising from them, have anything to do with the world?Kant sees the force of this difficulty, and thinks that, within the Platonicframework, it is insoluble. He divides previous philosophers intodogmatists and skeptics (A ix; A 856, B 884). Dogmatists like Descartesand Leibniz assume that human reason can comprehend ultimate reality.Their dogmatism involves three factors:1 Realism. Human thought can discover the nature of objective reality.2 Transcendence. Real knowledge is capable of extending beyondexperience to the supersensible. (See A 295–6, B 352.)3 Rationalism.4Descartes, for example, tries to demonstrate that God guarantees theveridicality of our a priori judgments by arguing that God exists and isentirely good. A good God, surely, would not be a deceiver. GrantingCartesian rationalism, we may see the problem generated by the possibilityof the evil deceiver as precisely that of realism: Why should we believe thatour thinking can discover the nature of objective reality? Descartes’ssolution relies on transcendence. We may take the form of thought implicitin the cogito, namely, the method of clear and distinct ideas, and apply itbeyond the realm of our own thinking to reality—indeed, to reality thattranscends all possible experience. But this, Kant sees, is just what is atissue. If realism is false—if our minds cannot discover the nature ofobjective reality—then why should we expect our modes of thinking,applied to the nature of that reality, to be reliable? It will not do to appeal totranscendence to justify realism, for the only argument for transcendencepresupposes realism. For example, Descartes’s third Meditation, arguing forthe existence and moral excellence of God, appeals to the premise that thereis at least as much reality in the cause as in the effect.5 Why, given only thecertain knowledge that I think and I exist, should I accept this principle ascertain? Descartes derives it by applying the method of clear and distinctideas beyond the mental realm of the cogito, which first justified it, to therealm of external, objective reality. Kant, for this reason, among others,rejects Descartes’s proof. But his reasoning is broader. Any argument forrealism within the dogmatist’s framework will rely on transcendence andmake a similarly illegitimate move.Skepticism, as Kant conceives it, also involves three factors:1 Subjectivism. Knowledge of objects reduces to knowledge of sense.2 Immanence. Real knowledge is limited to the sphere of senseexperience.3 Empiricism. (The denial of rationalism in either of its forms.)Skepticism, too, encounters difficulties. If dogmatism extends ourknowledge too far and too uncritically, skepticism seems unable toaccount for the knowledge we do have. Hume’s scandal of induction, forexample, illustrates that we cannot justify any causal knowledge we claimto have. It would have to reduce to a knowledge of items directlypresented in sensation, but, as Hume shows, it does not.Kant’s critical philosophy shares the immanence of skepticism, but alsothe rationalism of dogmatism. It transcends the distinction betweenrealism and subjectivism, holding that in a sense each is correct. Kant’ssynthesis of dogmatism and skepticism comes at the cost of distinguishingbetween the world of appearance—the phenomenal world—and the worldof things-in-themselves—the noumenal world. The former is essentiallysensible, and human thought can discover its nature. Things-inthemselves,in contrast, lie beyond our cognitive capacities. The dogmatistis right about the possibility of knowledge of objects, even a prioriknowledge of them; the skeptic is right about the limitation of knowledgeto the realm of experience.Both, however, misunderstand the status of objects of experience,thinking that they are in themselves as they appear to us. The phenomenalworld is both sensible and knowable; the noumenal world is neither. Withrespect to phenomena, therefore, the skeptic is vanquished; we can have apriori knowledge of objects of experience. With respect to noumena,however, the skeptic triumphs, for we can have no knowledge of things-inthemselves.Kant’s solution to the epistemological problem of Platonism goesbeyond the distinction between phenomena and noumena. It would beeasy to build that distinction into Descartes’s metaphysics, for example,without thereby making any headway on the skeptical problem. The keyto Kant’s solution resides in two additional changes to the traditionalframework. First, Kant explains the causal efficacy of the forms bytransforming them into categories, pure concepts of the understanding.They are innate cognitive capacities of a very general kind, but they arewholly mental; the question of their correspondence to abstract, mindindependentforms cannot arise. Without such forms there remains, ofcourse, the possibility that the categories do not correspond to objectiveand concrete reality. So, second, Kant reverses the traditional conceptionof the relation between thought and its object, or, as he puts it, betweenobject and concept. The Platonist traditionally sees the object as causallyresponsible for the veridical, perceptual thought of it. Kant’s Copernicanrevolution is precisely to reverse this understanding, maintaining insteadthat thought is causally responsible for constituting the object. The resultis not anarchy, a circumstance of “thinking making it so,” for theconstitution of objects proceeds according to the categories in a rulegovernedway. The rule-governed character of the construction makesknowledge of objects possible. More, it makes a priori knowledge of thempossible, for we can understand what we put into them—we can discoverthe rules according to which we constitute them. In this way Kant justifieshis realism with respect to the phenomenal world without any appeal totranscendence—indeed, in the face of its outright denial.THE CATEGORIESKant’s first change to the traditional Piatonistic framework is to substitutefor the forms the categories, pure concepts of the understanding. These areinnate ideas of the kind smiled upon by every concept rationalist. Butthere is no abstract realm of forms to which they must correspond. Theirindependence dissolves the epistemological difficulty arising for the aspectof the mind turned toward the forms in Platonic theories of mind.All knowledge, Kant observes, involves concepts; all concepts, in turn,“rest on functions,” “bringing various representations under one commonrepresentation” (A 68, B 93). The representations united in a concept maybe sensible intuitions or other concepts. Kant here makes an importantconcession to empiricists such as Hume: the content of concepts tracesultimately to sensation. Kant makes much of this in the TranscendentalDialectic to refute the transcendence thesis. In deriving the categories,however, he focuses on the mediate character of concepts. Concepts ofobjects always relate to those objects indirectly:Since no representation, save when it is an intuition, is in immediaterelation to an object, no concept is ever related to a conceptimmediately, but to some other representation of it, be that otherrepresentation an intuition, or itself a concept. Judgment is thereforethe mediate knowledge of an object, that is, a representation of arepresentation of it.(A 68, B 93)This has the consequence, critical to the Copernican revolution Kantmeans to effect, that both judgments and objects are products of synthesis.Knowledge, Kant contends, always takes the form of judgments. (This istrue at least for discursive knowledge, that is, knowing that, as opposed toknowing how or knowing to.) Judgments are combinations of concepts,which, in turn, are rules for synthesis, bringing together various sensations orconcepts. Concepts relate to objects because they are such functions ofsynthesis. To discover the pure concepts of the understanding, therefore, wemust find the functions of synthesis with a priori rather than empirical origins.The content of judgments, we might say, always has an empiricalsource, for the content of the concepts that comprise them arisesultimately from sensation. A concept unites sensible intuitions or otherconcepts that themselves unite sensible intuitions or other concepts. Thechain cannot proceed to infinity; at some point, it terminates in intuition.This may suggest that there are no pure concepts. But not all functions ofsynthesis operating in a judgment comprise part of its content. A judgmenthas both a content and a form. The content stems from experience, but theform does not. We can identify the pure concepts of the understanding,then, by examining the forms of judgment. Fortunately, there is already ascience that abstracts from the content of judgments and examines onlytheir forms—logic.6Kant, using Aristotelian logic, derives the following table of judgments(A 70, B 95):Every judgment, Kant contends, has a quantity, a quality, a relation, and amodality. In quantity, it is either universal (‘every metal is a body,’ forexample), particular (‘some metals are yellow’), or singular (‘Socrates is aphilosopher’). In quality, it is either affirmative (‘Socrates is mortal’),negative (‘Socrates is not mortal’), or infinite (‘Socrates is immortal’). Inrelation, judgments may be categorical (‘gold is a metal’), hypothetical (‘ifevery metal is a body, gold is a body’), or disjunctive (‘gold is a metal or arare earth’). And, in modality, judgments are problematic (‘gold may be ametal’), assertoric (‘gold is a metal’), or apodeictic (‘gold must be ametal’). The table of judgments thus gives what Kant takes to be anexhaustive account of the forms of judgment.From the perspective of modern logic, the table seems incomplete. Itdoes not include the quantity of ‘most metals are heavy’ or ‘many metalsoxidize’; it omits the modality of ‘Socrates ought to avoid hemlock.’ It hasno place for judgments with complement clauses, such as ‘Socrates knewthat the hemlock would kill him,’ and makes no provision for theabstraction relating ‘kind’ and ‘kindness,’ ‘friend’ and ‘friendship.’ It issilent about verb tense and aspect. (Kant considers time a form ofsensibility, not of judgment, and so considers it beyond the province oflogic.) It omits identity. Kant’s table is not only incomplete from a modernpoint of view; it is redundant. Many entries can be derived from otherswith the help of forms recognized by contemporary logicians. There is noconsensus on exactly what such a table would need to reflect all the formsof possible judgment. Kant is surely correct, however, that what we nowcall quantifiers, connectives, and modalities are required.The functions of judgment are not themselves the pure concepts of theunderstanding, but they correspond to them one-to-one. Kant lists thepure concepts of the understanding in his table of categories (A 80, B 106):Some of these relate directly to a corresponding entry in the table ofjudgments—‘Negative’ and ‘Negation,’ for example, or ‘Problematic’ and‘Possibility—Impossibility.’ Other connections—‘Disjunctive’ and ‘Ofcommunity,’ for instance—seem tenuous. How does Kant derive the tableof categories? His detailed arguments are not terribly important, for, as wehave seen, the entries on the table of judgments reflect an outdated logic.But it is important to understand what the categories are.Roughly speaking, what the table of judgments is to judgments, thetable of categories is to objects. Just as the table of judgments outlines thepossible logical forms of judgment, so the table of categories outlines thepossible logical forms of objects. This explains, for example, why,corresponding to the assertoric modality, we find ‘Existence-nonexistence’rather than Truth-falsehood.’ Synthesis of the manifold of intuition isessential to concepts. But synthesis alone does not suffice for knowledge.Knowledge of objects requires a unification of the pure synthesis of thesensible manifold. That is, the concept of an object is special: It is theconcept of a unified thing. In different terminology, concepts of objects notonly tell us when a certain predicable or general term applies, but alsowhen it is being applied to one and the same thing.7 The pure concepts ofthe understanding “apply a priori to objects of intuition in general” (A 79,B 105); they spell out the possible forms of such objects by indicating thepossible kinds of unity.Kant’s key assumption in deriving the categories in this way is that“The same function which gives unity to the various representations in ajudgment also gives unity to the mere synthesis of various representationsin an intuition” (A 79, B 105). Each such unity is a pure concept of theunderstanding. Why are the unifying functions in judgments and objectsthe same? We have seen above that judgments and objects are bothproducts of synthesis. Moreover, knowledge is always knowledge ofobjects through judgments. This suggests that judgments, at least of thesort appropriate to knowledge, are possible only by virtue of the unifyingactivity of the categories. Still, this does not suffice to establish the identityof function. It shows that the unifying activity in a judgment presupposesthe unifying activity in an intuition, not that they have the same form.Kant’s argument turns on his notion of a concept. The unity ofjudgments and objects alike is a unity in a concept. This not only explainsthe link between the table of judgments and the table of categories; it alsoexplains why the pure concepts of the understanding have a priori validity,avoiding the challenges of the skeptics.Concepts of objects in general thus underlie all empirical knowledgeas its a priori conditions. The objective validity of the categories as apriori concepts rests, therefore, on the fact that, so far as the form ofthought is concerned, through them alone does experience becomepossible. They relate of necessity and a priori to objects ofexperience, for the reason that only by means of them can any objectwhatsoever of experience be thought.(A 93, B 126)To understand the role that concepts play in Kant’s theory of mind,however, we must examine his account of the kinds of synthesis.THE SUBJECTIVE DEDUCTIONKant’s argument for the first key to his solution to the problems arisingfrom the Platonic framework—the pure concepts of the understanding—also defends and develops the second key, the Copernican revolution. Theargument occupies the portion of the Critique he entitles “Thetranscendental deduction of the pure concepts of the understanding.”There are, however, two very different versions of this argument in thefirst and second editions of the Critique. The first edition version presentsa model of how the mind constructs objects from the data of sense,arguing that the pure concepts of the understanding are essential to theprocess. The second version presents no model, but analyzes theimplications of the “I think.” The general strategy, however, remains thesame. The categories are “concepts of an object in general” (B 129); theyare “a priori conditions of the possibility of experience” (A 94, B 126). Weare able to experience objects, that is, only because we have the concept ofan object. We do not derive this concept from experience, for we could notexperience anything as an object without already having the generalconcept of an object.The transcendental deduction of the first edition is notoriously difficult;Kant apparently pieced it together from four manuscripts composed atdifferent times and reflecting four different stages of his thinking.8 Itmoreover includes two arguments: an “objective” deduction seeking toestablish “the objective validity of a priori concepts,” and a “subjective”deduction investigating “the faculty of thought” (A x–xi).The subjective deduction outlines a three-part model of mentalactivity—specifically, of the generation of a judgment of experience suchas ‘This is a triangle.’ This model shows, in Kant’s view, how judgments ofexperience require the categories. Kant defines a pure concept of theunderstanding as a concept without any empirical content, that is, as onethat “universally and adequately expresses…a formal and objectivecondition of experience” (A 96). His strategy is to “prove that by theirmeans alone an object can be thought” (A 97). This, he says, “will justifytheir objective validity,” for, if the categories are necessary conditions ofexperience, nothing could be an object of experience without complyingwith the categories.Sensation, Kant holds, is a manifold. It bombards us with a plethora ofpossible sources of information. Out of this multiplicity we synthesizerepresentations, concepts, and judgments. The first act of synthesis is thatof apprehension in intuition. All sensations occur in time.9 We bind themultiplicity sensation offers into unified items of sense. A sensation of atriangle, for example, may consist of various visual and tactile impressionsreceived over a short interval of time. We experience it as a singlesensation, usually without being aware of its complex nature. In short, weorganize the data of sense into discrete sensations. This organization is thesynthesis of apprehension in intuition.The second act is the synthesis of reproduction in imagination. Kantargues that “experience as such necessarily presupposes the reproducibilityof appearances” (A 101–2). His premises concern pure intuitions of spaceand time—drawing a line in thought, for example, or thinking of anumber—which, he maintains, are possible a priori. Kant’s theory of pureintuitions is controversial and somewhat obscure. But we can argue thepoint on other grounds. Sensations, considered individually, are not fullblownobjects of experience. We can have many sensations of the sameobject. We might view a triangle, for example, from many differentperspectives. To make any judgment about such an object of experience,we must relate sensations to each other, being capable of recognizing themas sensations of the same object. How we do this is of course an empiricalquestion. But do it we must if we are ever to form concepts of objects ofexperience.That brings us to the third act, the synthesis of recognition in a concept.Throughout this discussion, Kant seems to operate with two ideas of whatconcepts are. The awareness of the unity of various sensations, Kant says,is a concept—etymologically, a “thinking together.” Having relatedsensations in the synthesis of reproduction in imagination, we form aconcept through our consciousness of their unity as an object. But Kantalso speaks of a concept as a rule: “a concept is always, as regards itsform, something universal which serves as a rule” (A 106). Specifically, aconcept is a rule for the synthesis of the manifold of intuition. These twonotions of concepts are intimately connected:the unity which the object makes necessary can be nothing else thanthe formal unity of consciousness in the synthesis of the manifold ofrepresentations. It is only when we have thus produced syntheticunity in the manifold of intuition that we are in a position to say thatwe know the object. But this unity is impossible if the intuitioncannot be generated in accordance with a rule by means of such afunction of synthesis as makes the reproduction of the manifold apriori necessary, and renders possible a concept in which it is united.Thus we think of a triangle as an object, in that we are conscious ofthe combination of three straight lines according to a rule by whichsuch an intuition can always be represented. This unity of ruledetermines all the manifold, and limits it to conditions which makeunity of apperception possible.(A 105)Essential to recognizing something as an object, then, is a consciousness ofits unity. But this consciousness is possible only if the object is constructedaccording to a rule. We can recognize a collection of intuitions asconstituting a single object only by having a rule for uniting them into thatobject. We take a triangle as a single object rather than three distinct linesegments that happen to intersect because we have a rule for uniting thosesegments. Without such a rule, we would be left with a manifold. The twonotions of concept are connected, then, in that we are aware of unity(concept in sense one) according to a rule (concept in sense two).The rule-governed character of object construction brings with it a kindof necessity. To count as a triangle, for example, something must be aplane figure with three sides and three angles. So, it is a necessary truththat triangles have three sides and three angles. This, it might seem, is notthe sort of necessity that interests Kant; ‘triangles have three angles’ isanalytic. But when we ask what necessary truths stem, not from the rulefor constructing triangles or any other kind of object, but from the rulegovernedconstructions of objects in general, we obtain a more interestinganswer. All objects must be unified, for example; the concept of an objectis the concept of a single thing.Necessity, in turn, implies transcendental conclusions about ourcontributions to objects.All necessity, without exception, is grounded in a transcendentalcondition. There must, therefore, be a transcendental ground of theunity of consciousness in the synthesis of the manifold of all ourintuitions, and consequently also of the concepts of objects ingeneral, and so of all objects of experience, a ground without whichit would be impossible to think any objects for our intuitions.(A 106)Kant’s argument begins with the premise that necessity is grounded in atranscendental condition. He does not argue for it because he takes it asevident from Hume’s writings. Necessary connections, Hume observes,cannot be found in experience. We are directly aware of a succession ofthings but not of the connections between items of the sequence. (In FrankO’Malley’s words, “Life is just one damned thing after another.”) Ourconcept of necessity, Hume concludes, must come from us, not from whatwe experience. So far, Kant agrees. But Hume goes on to attribute thesource of our concept of necessity to the passionate side of our nature, toa feeling of expectation. Kant, in contrast, finds necessity’s source in theunity of objects. We experience objects, not just a whirling mass ofsensations. And, as we have seen, it is a necessary truth that all objects areunified. Kant concludes that there is a transcendental ground of that unity.The source of the unity of objects, moreover, is also the source of theconcept of an object in general; it thus underlies our experience of anyobject.The transcendental ground of the unity Kant terms transcendentalapperception. When we reflect on the contents of our own consciousness,as Hume stresses, we are aware only of a succession of mental states; wedo not confront a unified self. The contents of consciousness are alwayschanging: “No fixed and abiding self can present itself in this flux of innerappearances” (A 107). Thus, we find no unity in what Kant calls empiricalapperception or inner sense. But there must be a ground of unity in us.This brings us to Kant’s key contention: The ground of the consciousnessof unity is the unity of consciousness. The source of our consciousness ofthe unity of objects is the underlying unity of our consciousness itself. Thisunity of apperception is “the a priori ground of all concepts” (A 107), forall concepts unify the manifold of sensibility into objects. The mostgeneral concepts, relating to the form of an object in general, are thecategories. The unity of apperception and with it the categories underliethe lawlike connections we find among objects of experience and thesynthetic a priori knowledge we have of them.The subjective deduction, then, means to spell out Kant’s Copernicanrevolution in subjective detail. We can know certain truths about objectsindependently of experience, for we can uncover the pure concepts of theunderstanding relating to the form of an object in general. These conceptsdo not arise from experience; they underlie the possibility of experience.So, we can know a priori that any experience will conform to them. Thisestablishes realism, the view that we can attain knowledge of objectivereality, within the realm of objects of experience. It also establishesconcept rationalism. Most importantly, it solves the traditional Platonicproblem of the conformity of the world to our innate ideas withoutinvoking God, ex caelo or ex machina.THE OBJECTIVE DEDUCTIONKant nevertheless views the subjective deduction as inessential to the successof the critical enterprise. He needs to establish the objective validity of thecategories; he does not need to spell out the subjective details of the facultyof thought. Kant is trying to show that the categories underlie ourjudgments about objects. Judgments, however, are the products of the threestagemodel of mental activity outlined in the subjective deduction, and thecategories enter the model only in the third stage. The first two stages arethus inessential to the argument. The subjective deduction, moreover, treatsthe crucial third stage cursorily, leaving the role of the categories unclear. So,Kant begins another argument, the objective deduction, to treat only therelation between judgments and the categories. In the second edition, Kantomits the subjective deduction entirely and elaborates the objectivededuction of the first edition.Kant begins, not by considering the process of transforming the data ofsense into judgments, but by reflecting on the form of sensibility itself.“We must begin with pure apperception,” he says. “Intuitions are nothingto us, and do not in the least concern us if they cannot be taken up intoconsciousness” (A 116). That is, the model of mental activity presented inthe subjective deduction presupposes, even at its earliest stage, the unity ofconsciousness. It relates the data of sense to a single consciousness or mindin which reside the faculties of sensibility, imagination, and understanding.For the manifold representations, which are given in an intuition,would not be one and all my representations, if they did not allbelong to one self-consciousness. As my representations (even if I amnot conscious of them as such) they must conform to the conditionunder which alone they can stand together in one universal selfconsciousness,because otherwise they would not all withoutexception belong to me.(B 132–3)The unity of consciousness thus underlies the possibility of sensation andthought. Kant obtains “the transcendental principle of the unity of all thatis manifold in our representations, and consequently also in intuition” (A116), which he terms “the highest principle in the whole sphere of humanknowledge” (B 135). All representations are representations preciselybecause they can be represented in empirical consciousness. But anempirical consciousness requires a transcendental consciousness, for it isunified without containing its unity as an element. All representationstherefore presuppose the transcendental unity of apperception.To put Kant’s argument differently: Empirical consciousness, as far asits contents are concerned, is a mixed bag. We cannot discover its unityfrom its contents. Nor can we determine that a given succession of mentalstates is unified into a single empirical consciousness by examining thecontents of those states: “the combination (conjunctio) of a manifold ingeneral can never come to us through the senses, and cannot, therefore, bealready contained in the pure form of sensible intuition” (B 129). That agiven representation is Jones’s representation, therefore, we cannotanalyze by appeal to monadic properties of that representation. We cannotanalyze it by appeal to relations among representations. We must insteadanalyze it by appeal to a relation between the representation andsomething else. Whatever is responsible for the unity of consciousness isnot to be found in empirical consciousness but in the relation between itscontents and something else, outside and underlying empiricalconsciousness. That is the transcendental unity, “that which itself containsthe ground of the unity of diverse concepts in judgment, and therefore ofthe possibility of the understanding, even as regards its logicalemployment” (B 131). At one point Kant even identifies thetranscendental unity with the understanding (B 134 n.). Thetranscendental unity of apperception manifests itself in the ‘I think’ thatwe can append to all our judgments and representations:It must be possible for the ‘I think’ to accompany all myrepresentations; for otherwise something would be represented in mewhich could not be thought at all, and that is equivalent to sayingthat the representation would be impossible, or at least would benothing to me.(B 132)This argument for the transcendental unity of consciousness allows Kantto speak of a transcendental principle: “a principle of the synthetic unityof the manifold in all possible intuition” (A 117). The principle of theunity of consciousness itself is analytic, roughly of the form ‘I am I’ (B135). But the transcendental principle Kant obtains from it is nonethelesssynthetic. We have seen that a sensation is part of Jones’s empiricalconsciousness if and only if it stands in the appropriate relation to Jones’stranscendental unity of apperception. This, Kant insists, is a necessarytruth about our kind of consciousness, one which permits a prioriknowledge of the unity of consciousness without manifesting that unityexplicitly in its contents. It follows that Jones can receive a sensation onlyif it stands in relation to Jones’s transcendental unity. We can know apriori, then, that any sensation must relate to the transcendental unity:“all the manifold of intuition should be subject to conditions of theoriginal synthetic unity of apperception” (B 136). This proposition,furthermore, is synthetic. We derive it, not by analyzing the concept ofsensation or even the concept of the transcendental unity, but byconnecting the two by way of the transcendental argument just reviewed.As we might expect concerning the argument for any synthetic truth, itrests on experience. But it permits a priori knowledge, knowledge that canbe derived independently of experience and that holds necessarily, becauseit concerns the form of any possible experience.Kant is driving toward the conclusion that “appearances have anecessary relation to the understanding” (A 119). Appearances, he says,are “data for a possible experience”; they therefore have to relate to theunderstanding. The transcendental unity of apperception is responsible forwhat Kant calls the affinity of our representation—that is, their being ourrepresentations, their constituting a single empirical consciousness—andalso the rule-governed character of the synthesis of the manifold ofintuition. If that synthesis were not rule-governed, the combination of thedata of sense would not yield knowledge but random and “accidentalcollocations” (A 121) such as the products of imagination in the usualsense. We may freely combine concepts, to form the notion of a threeheadeddragon or a golden mountain, but we gain no knowledge of whatis actual from exercising that freedom. We attain knowledge of objectsbecause the construction of objects actually presented in experience is rulegoverned.Sensibility presents us with the data of experience, giving it the form ofspace and time; the understanding formulates judgments. The rulegovernedsynthesis linking the two is a product of the imagination and isunified by pure apperception. Our perception of a triangle, for example, isrule-governed; we cannot connect any sensations we like, label them atriangle, and obtain knowledge. The rule, in this case, is quite specificabout geometrical form. Underlying such specific rules, Kant points out, isa general set of rules for generating concepts of objects. We can callsomething a triangle only if it has three sides and three angles. Morebroadly, we can call something an object only if it meets certainconditions, that is, satisfies certain rules. Those rules are specified by thecategories. Kant therefore characterizes the understanding as the faculty ofrules.The objective deduction, Kant maintains, shows that we can knowobjects because we construct them: “Thus the order and regularity in theappearances, which we entitle nature, we ourselves introduce. We couldnever find them in appearances, had not we ourselves, or the nature of ourmind, originally set them there” (A 125). The understanding,consequently, is nothing less than “the lawgiver of nature” (A 126). Thisfollows from Kant’s argument, for it has shown that the transcendentalunity is “an objective condition of all knowledge. It is not merely a conditionthat I myself require in knowing an object, but is a condition under whichevery intuition must stand in order to become an object for me” (B 138).THE DIALECTICThe Transcendental Analytic and related portions of the Critique attemptto justify Kant’s rationalism. The Transcendental Dialectic, whichcomprises most of the second half of the book, tries to justify Kant’s thesisof immanence. As Kant puts it, the topic of the Dialectic is illusion.Certainly, he means to show that the hope of extending knowledge beyondthe realm of sense experience is illusory. But he uses the term ‘illusion’ in amore specific sense: “an illusion may be said to consist in treating thesubjective condition of thinking as being knowledge of the object” (A 396;see A 297, B 353–4). The key to the Analytic is the Copernican revolution,the idea that the faculty of thinking constitutes objects. This should nottempt us to conclude, however, that subjectivity and objectivity—thinkingand knowing—match effortlessly. Clearly we may think of things that arenot objectively real through imagination. We may also make mistakes.Most seriously, our thinking extends easily beyond the realm of senseexperience. We may engage in metaphysical contemplation, arguing aboutthe freedom of the will, the existence of God, and the mortality orimmortality of the soul. But Kant denies that we can attain any realknowledge of these matters.Kant differentiates thinking and knowing, subjectivity and objectivity,by distinguishing the transcendental unity of apperception from thesubjective unity of consciousness. To understand the distinction, we mustreturn to the argument of the Transcendental Deduction, which uses thesubjective unity to argue for the transcendental unity. The subjective unityof consciousness is a determination of inner sense. The manifold ofintuition is given to us in experience, and our experience constitutes asingle experience; this is the subjective unity. The manifold of intuition isunited in the concept of an object through the transcendental unity. Thesubjective unity of consciousness is a condition of all thinking; thetranscendental unity is a condition of all knowing.This distinction is extremely important for Kant; transcendentmetaphysics results from its confusion. We may think whatever we like inimagination. We may connect concepts and intuitions freely withoutconcern for their presence in experience. The transcendental unity,however, directs our thought toward an object and toward reality. We canknow a synthetic judgment only by some connection with experience. Thisis why we cannot have knowledge that transcends experience: “Thepossibility of experience is, then, what gives objective reality to all our apriori modes of knowledge” (A 156, B 195). Indeed, it explains Kant’s firstexample of a synthetic a priori principle: “every object stands under thenecessary conditions of synthetic unity of the manifold of intuition in apossible experience” (A 158, B 197).Kant’s distinction between the transcendental and subjective unities hastwo important consequences. First, a rational psychology—a disciplinetaking the ‘I think’ as its sole text (A 343, B 401) and amounting to atheory of the soul—is impossible. One might suppose, given the account ofthe transcendental unity, that the “I,” or, to use Kant’s term, the soul, is asimple, unified substance, and that we can discover this a priori. This,however, is a confusion. One can argue that the representation of the “I”is a representation of a substance, of something simple and unified. But todeduce that the “I” is a substance, simple and unified, is to commit afallacy.10 In fact, it is to invite the skeptic’s objections all over again.Nothing here guarantees the veridicality of our representations. From theperspective of transcendental (rather than rational, that is, rationalist andtranscendent) psychology, the “I” is “completely empty”: “it is a bareconsciousness which accompanies all concepts. Through this I or he or it(the thing) which thinks, nothing further is represented than atranscendental subject of the thoughts=X” (A 346, B 404).As with the self, so with things-in-themselves. The second consequenceof Kant’s distinction is thus that knowledge of things-in-them-selves isimpossible; knowledge is limited to the sphere of experience. The limits ofknowledge become clear in thinking about the role of the categories. Thepure concepts of the understanding are conditions of the possibility ofexperience. They have a priori validity, against the claims of the skeptic,because “all empirical knowledge of objects would necessarily conform tosuch concepts, because only as thus presupposing them is anythingpossible as an object of experience” (A 93, B 126). Objects of experiencemust conform to the categories. Objects beyond the realm of experience,however, face no such constraint. In fact, we have no reason to believethat the categories apply to them at all. The categories conform to objectsof possible experience because we synthesize those objects from the dataof sensibility. What lies beyond sensibility lies beyond the categories, forwe have no reason to believe that it results from such a process ofsynthesis.This means that transcendent metaphysics is impossible. Metaphysicalknowledge, to be interesting, must be knowledge of the world; it cannot bemerely verbal. So, it must consist of synthetic propositions. Moreover, itcannot rely on experience; to be necessary and nonempirical, it must be apriori. Kant, as a rationalist, is committed to the possibility of synthetic apriori knowledge. But such knowledge is possible only transcendentally,that is, through the contemplation of what makes experience possible. Wesecure the possibility of synthetic a priori knowledge by arguing for thecategories. They apply, however, only to objects of possible experience.Kant derives rationalism, therefore, only by undercutting transcendence.No other objects, besides those of the senses, can, as a matter of fact,be given to us, and nowhere save in the context of a possibleexperience; and consequently nothing is an object for us, unless itpresupposes the sum of all empirical reality as the condition of itspossibility.(A 582, B 610)We can witness Kant’s application of his principle of immanence in hisrefutation of the cosmological argument for the existence of God. Thatargument appears in Aquinas, for example, as follows:In the observable world causes are to be found ordered in series; wenever observe, or even could observe, something causing itself, forthis would mean that it preceded itself, and this is impossible. Such aseries of causes, however, must stop somewhere. For in all series ofcauses, an earlier member causes an intermediate, and theintermediate a last (whether the intermediate be one or many). If youeliminate a cause, you also eliminate its effects. Therefore, there canbe neither a last nor an intermediate cause unless there is a first. Butif the series of causes goes on to infinity, and there is no first cause,there would be neither intermediate causes nor a final effect, which ispatently false. It is therefore necessary to posit a first cause, which allcall “God.”11Kant’s transcendental critique of this argument alleges “a whole nest ofdialectical assumptions,” of which he points out several: (a) The argumentassumes that each event in the observable world has a cause. Kant agrees;he regards it as a synthetic a priori truth. But, as such, “This principle isapplicable only in the sensible world; outside that world it has no meaningwhatsoever” (A 609, B 637). (b) Why can’t a series of causes go on toinfinity? Kant finds nothing to justify this assumption even in the sensibleworld, (c) Is it true that, if you eliminate a cause, you eliminate its effects?Even if this holds in experience, we have no justification for extending itbeyond experience, (d) Finally, why should we identify the first cause asGod? Philosophers have understood God as the perfect being, “that, thegreater than which cannot be conceived,” the being more real than anyother, and the necessarily existent being. To conclude that the first cause isGod, we must show at least that the first cause is perfect and necessary.Nothing in the proof accomplishes this. Consequently, Kant maintainsthat “the so-called cosmological proof really owes any cogency which itmay have to the ontological proof from mere concepts” (A 607, B 635),for it assumes that perfection, necessity, and being the first cause all holdof the same thing.The ontological proof appears in Anselm in the following form:Certainly, this being exists so truly that one cannot even think that itdoes not exist. For whatever must be thought to exist is greater thanwhatever can be thought not to exist. Hence, if that greatestconceivable being can be thought not to exist, then it is not thegreatest conceivable being, which is absurd. Therefore, something sogreat that a greater cannot be conceived exists so truly that it cannoteven be thought not to exist.12The argument means to show that perfection entails necessity. That God isperfect Anselm takes as an analytic truth, as following from a definition of‘God.’ He concludes that God exists necessarily.Kant’s assault on this argument is more complicated than his attack onthe cosmological proof, but also more illuminating. This proof is aparadigm example of illusion, the mistaking of the subjective for theobjective. It tries to establish the necessary existence of God from the mereconcept of God. Kant is willing to grant that the argument shows that theconcept of God, so defined, includes the concept of existence. But hedenies that this implies anything at all about the existence of God inreality.The key to Kant’s attack on the ontological argument is hiscontention that ‘being’ is not a real predicate. Kant defines adetermining predicate as “a predicate which is added to the concept ofthe subject and enlarges it” (A 598, B 626). It follows that a judgmentwith a determining predicate must be synthetic, for the predicate mustenlarge the subject; it cannot already be contained in it. “‘Being’,”Kant insists, “is obviously not a real predicate; that is, it is not aconcept of something which could be added to the concept of a thing”(A 598, B 626). A real predicate is capable of serving as a determiningpredicate. ‘Being,’ evidently, is not.We might be tempted to conclude that existential judgments such as‘God is’ or ‘God exists’ are analytic, for ‘being’ cannot serve as adetermining predicate. But Kant clearly maintains that all existentialjudgments are synthetic. He argues specifically that ‘God exists’ is notanalytic, and concludes, “as every reasonable person must, that allexistential propositions are synthetic” (A 598, B 626). It follows that‘being’ cannot be contained in the concept of a thing. But how canexistential judgments be synthetic if they lack determining predicates?13A synthetic judgment is not merely verbal; its predicate, according toKant, must add something not already included in its subject. ‘Being,’then, must add something to every subject concept. Yet it is notdetermining; it does not add to and enlarge the subject concept. ‘Being’adds something that does not enlarge the concept of the subject.To understand how this is possible, we must return to Kant’s theoryof concepts. Concepts are functions of synthesis that organize andunify the material of sense. They mold the data of sense intoperceptions of objects (A 68, B 93, B 95). Consequently, their contentrelates essentially to the manifold of sense. In language and in thought,we can manipulate items however we like. Only through links tointuition, actual or possible, can we move from thinking to knowledge,activating the transcendental unity and giving our thoughts objectivevalidity. (See A 155, B 194–5, B 146, B 165–6.) In short, concepts havecontent by virtue of the patterns of possible intuitions falling underthem. This entails that ‘being’ is not a real predicate, for it lacks thissort of content. It cannot enlarge a subject concept; any intuitionfalling under the concept of a dollar falls under the concept of anexisting dollar, and vice versa (A 599–600, B 627–8). It follows,moreover, that existential judgments are synthetic, for existence cannotbe part of the content of a subject concept (A 225, B 272).If ‘being’ lacks content definable in terms of the manifold of sense, whatdoes it contribute to a judgment? Existential judgments do not enlarge oralter a rule for the synthesis of the manifold of intuition, but express therelation of the rule to the understanding. For Kant, then, ‘being’ isrelational. The same holds of possibility and necessity, which share thefourth, “Modality” portion of the table of categories.14 Kant maintainsthat the modality of a judgment adds nothing to the judgment’s content.Instead, it determines the judgment’s relation to the understanding: “Theprinciples of modality thus predicate of a concept nothing but the actionof the faculty of knowledge through which it is generated” (A 234, B 286–7). Existence and the other modalities contribute “a relation to myunderstanding” (A 231, B 284), determining “only how the object,together with all its determinations, is related to understanding and itsempirical employment, to empirical judgment, and to reason in itsapplication to experience” (A 219, B 266).Kant compares the ‘being’ at stake in existential judgments to the‘being’ of the copula (A 74, B 100; A 598–9, B 626–7). Both “distinguishthe objective unity of given representations from the subjective” (B 141–2). Only by relating the terms of a judgment to the transcendental unity ofapperceptiondoes there arise from this relation a judgment, that is, a relationwhich is objectively valid, and so can be adequately distinguishedfrom a relation of the same representations that would have onlysubjective validity—as when they are connected according to thelaws of association.(B 142)‘Being’ in both roles distinguishes the subjective from the objective.This is why the ontological proof is Kant’s paradigm case of dialecticalillusion. The advocate of the proof mistakes the subjective for theobjective, failing to recognize that God’s existence or necessity cannot beestablished analytically, from the definition of ‘God’ alone. In saying thatsomething exists, we assert a relation to the understanding; we assert thatwe may experience the object, or stand in relation to it by way ofempirical laws (A 219, B 266–7; A. 234 n., B 287 n.; A 616, B 644). Andthis cannot be derived from concepts alone. It follows that nothing existswith analytic or logical necessity:If I take the concept of anything, no matter what, I find the existenceof this thing can never be represented by me as absolutely necessary,and that, whatever it may be that exists, nothing prevents me fromthinking its nonexistence.(A 615, B 643)We can now see how Kant can practice the transcendental method whilerejecting transcendent metaphysics. The latter confuses the subjective andthe objective, failing to recognize that concepts have content only inrelation to experience. The transcendental method, however, focusesdirectly on the relation to the understanding at stake in questions ofmodality. Kant deduces the categories by reflecting on the sort of relationthat must hold if experience of objects is to be possible.HUMANISMKant carefully distinguishes his view from the idealism of Berkeley, whichassails the notion of a reality beyond the realm of ideas. Kant’s solution toPlatonism’s problems relies on distinguishing phenomena from noumena.Kant thus insists on the need to recognize nonmental objects, things-inthemselves,of which our appearances are appearances.Kant nevertheless realizes that his theory is a form of idealism—transcendental idealism, he calls it—for truth, objectivity, and existence,within the theory, become fundamentally epistemic notions. The sameholds of all the modalities—possibility, truth or existence, and necessity —for all have the same function of relating a judgment to the understanding.Metaphysics is inseparable from epistemology; the root notions ofmetaphysics are all, in the end, epistemological notions.Kant’s epistemic conception of modality underlies his identification of apriori and necessary judgments. Saul Kripke has attacked this identification,pointing out that a prioricity is a matter of epistemology—can something beknown independently of experience?—while necessity is a matter ofmetaphysics. Kripke has alleged, against Kant, that there can be contingent apriori and necessary a posteriori truths.15 This seems plausible on themetaphysical view of necessity that Leibniz and Kripke share, namely, thatnecessity is truth in all possible worlds. But Kant rejects that view. Ajudgment is a priori if it can be known independently of all experience; if, thatis, it holds no matter what experience might yield, or, to put it differently, if itholds no matter what the world looks like. A judgment is necessary, on theLeibniz-Kripke view, if it holds no matter what the world is like. Kant doesnot confuse these notions; he rejects the latter precisely because it ismetaphysical in a transcendent sense. The truth of skepticism is that wecannot know what the world is like. The only notion of modality we can useis epistemic, in which we consider possible experiences rather than possibleworlds. On this conception, of course, the a priori and the necessary are notonly equivalent, but obviously so.Moreover, it becomes possible to attain knowledge of necessary truthsabout objects of experience. Reason gets itself into trouble when it tries toleave the realm of possible experience. Kant is able to defend ourknowledge of necessary truths against skeptics such as Hume because, forhim, the a priori and necessary extend to the immanent sphere only, not tothe transcendent. They are limited to the realm of possible experience. If apriori judgments were necessary in a strong metaphysical sense, thenKant’s immanence thesis would be hard to understand.The epistemic character of the basic notions of metaphysics—whenthese notions and, correspondingly, metaphysics are properly construed—is the central consequence of Kant’s Copernican revolution. It wouldbecome fundamental to virtually all nineteenth-century approaches tophilosophy. Skepticism, perhaps the chief philosophical puzzle sinceDescartes, would give way to puzzles arising from Kant’s uniquelyhumanistic idealism. For Kant, as for the ancient Sophist Protagoras, manis the measure of all things. Kant, of course, takes the definite article hereseriously. There is one and only one measure: the categories underlie allpossible experience. Not everyone would agree. The nature and especiallythe uniqueness of the measure would define the chief battleground forphilosophers during the next two centuries.NOTES1 R.Rorty, Philosophy and the Mirror of Nature (Princeton: Princeton UniversityPress, 1979), p. 149; N.Kemp Smith, A Commentary to Kant’s Critique of PureReason (Atlantic Highlands, NJ: Humanities Press, 1962), p. vii.2 This and other citations from the Critique of Pure Reason are from thetranslation of N.Kemp Smith (London: Macmillan, 1929; New York: StMartin’s Press, 1965). Throughout, any emphasis in the quotations is Kant’s;the pagination is that of the original first (A) and second (B) editions.3 H.Vaihinger, Commentar zu Kant’s Kritik der Reinen Vernunft, Vol. I(Stuttgart: Spemann, 1881), pp. 117–20.4 The analysis is Vaihinger’s. See ibid., p. 50; Kemp Smith, op. cit., pp. 13–14.5 Descartes, Meditations, III.6 Kant often speaks of the content and form of judgments in just this way.Introducing the table of judgments, he writes, “If we abstract from all contentof a judgment, and consider only the mere form of understanding,” we derivethe table (A 70, B 95). At other times, however, he treats the form and contentvery differently. Modality, for example, differs from the other aspects ofjudgment in the table in that “it contributes nothing to the content of ajudgment (for, besides quantity, quality, and relation, there is nothing thatconstitutes the content of a judgment)” (A 74, B 100). These are plainlyinconsistent. In the former passage, Kant speaks of empirical content or, moreprecisely, the content of the impure concepts in a judgment; in the latter, hespeaks of logical content. It is tempting to identify the form of a judgmentwith its logical content, but Kant’s theory of the modalities makes thatimpossible. See my “Kant on Existence and Modality,” Archiv für Geschichteder Philosophie, 64, 3 (1982): 289–300.7 That is, concepts of objects are rules of individuation as well as application.For a sophisticated modern treatment of this distinction, see A.Gupta, TheLogic of Common Nouns (New Haven: Yale University Press, 1984).8 See H.Vaihinger, “Die transcendentale Deduktion der Kategorien,”Gedenkschrift für Rudolf Haym (1902); Kemp Smith, op. cit., pp. 202ff.9 Kant’s theory of time occupies part of the Transcendental Aesthetic. In brief,time is the form of inner sense, the progression of sensations, thoughts, and, ingeneral, representations that constitutes empirical consciousness. Space andtime, Kant argues, are a priori forms of intuition, for they are necessaryconditions of sensation. We cannot sense anything without sensing it in spaceand time, that is, as spatially and temporally located. Time is moreover theform of inner sense because we cannot think anything without thinking it intime, that is, without our thought being part of a temporal sequence.10 See W.Sellars, “Some Remarks on Kant’s Theory of Experience” and “…this Ior he or it (the thing) which thinks…,” in his Essays on Philosophy and itsHistory (Dordrecht: Reidel, 1974), pp. 44–61, 62–92.11 St Thomas Aquinas, Summa Theologiae, la. 2; my translation.12 St Anselm of Canterbury, Proslogion, III; my translation.13 For more on this apparent contradiction, see J.Shaffer, “Existence,Predication, and the Ontological Argument,” Mind, 71 (1962): 307–25;W.H.Walsh, Kant’s Criticism of Metaphysics (Edinburgh: EdinburghUniversity Press, 1975), p. 7; G.Vick, “Existence was a Predicate for Kant,”Kant-Studien, 61 (1970): 357–71, esp. 363–4; R.Coburn, “Animadversionson Plantinga’s Kant,” Ratio, 13 (1971): 19–29, esp. 21–2; R.Campbell, “RealPredicates and ‘Exists’,” Mind, 83 (1974): 96ff.; and my “Kant on Existenceand Modality,” op. cit., pp. 291–5.14 One of the few commentators to observe this is H.Heimsoeth, TranszendentaleDialektik (Berlin: de Gruyter, 1969), Vol. III, p. 480.15 See S.Kripke, Naming and Necessity (Cambridge, Mass.: Harvard UniversityPress, 1972, 1980), pp. 34–9.SELECT BIBLIOGRAPHYOriginal language editions2.1 Kant, I. 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