Thus the main question, How are synthetic judgments a priori possible? divides into the subordinate questions, How is pure mathematics possible? How is pure natural science possible, and, How is metaphysics (in two senses: metaphysics in general, and metaphysics as science) possible? The Transcendental Aesthetic (the critique of sensibility or the faculty of intuition) answers the first of these questions; the Transcendental a.n.a.lytic (the critique of the understanding), the second; and the Transcendental Dialectic (the critique of "reason" in the narrower sense) and the Transcendental Doctrine of Method (Methodenlehre), the third. The a.n.a.lytic and the Dialectic are the two parts of the Transcendental "Logic" (critique of the faculty of thought), which, together with the Aesthetic, forms the Transcendental "Doctrine of Elements" (Elementarlehre), in contrast to the Doctrine of Method. The Critique of Pure Reason follows this scheme of subordinate division, while the Prolegomena co-ordinates all four parts in the manner first mentioned.
Let us antic.i.p.ate the answers. Pure mathematics is possible, because there are pure or a priori intuitions (s.p.a.ce and time), and pure natural science or the metaphysics of phenomena, because there are a priori concepts (categories) and principles of the pure understanding. Metaphysics as a presumptive science of the suprasensible has been possible in the form of unsuccessful attempts, because there are Ideas or concepts of reason which point beyond experience and look as though knowable objects were given through them; but as real science it is not possible, because the application of the categories is restricted to the limits of experience, while the objects thought through the Ideas cannot be sensuously given, and all a.s.sumed knowledge of them becomes involved in irresolvable contradictions (antinomies). On the other hand, a science is possible and necessary to teach the correct use of the categories, which may be applied to phenomena alone, and of the Ideas, which may be applied only to our knowledge of things (and our volition), and to determine the origin and the limits of our knowledge-that is to say, a transcendental philosophy. In regard to metaphysics (knowledge from pure reason), then, this is the conclusion reached: Rejection of transcendent metaphysics (that which goes beyond experience), recognition and development of immanent metaphysics (that which remains within the limits of possible experience). It is not possible as a metaphysic of things in themselves; it is possible as a metaphysic of nature (of the totality of phenomena), and as a metaphysic of knowledge (critique of reason).
The interests of the reason are not exhausted, however, by the question, What can we know? but include two further questions, What ought we to do? and, What may we hope? Thus to the metaphysics of nature there is added a metaphysics of morals, and to the critique of theoretical reason, a critique of practical reason or of the will, together with a critique of religious belief. For even if a "knowledge" of the suprasensible is denied to us, yet "practical" grounds are not wanting for a sufficiently certain "conviction" concerning G.o.d, freedom, and immortality.
After carrying the question of the possibility of synthetic judgments a priori from the knowledge of nature over to the knowledge of our duty, Kant raises it, in the third place, in regard to our judgment concerning the subjective and objective purposiveness of things, or concerning their beauty and their perfection, and adds to his critique of the intellect and the will a critique of the faculty of aesthetic and teleological judgment.
The Kantian philosophy accordingly falls into three parts, one theoretical, one practical (and religious), one aesthetic and teleological.
Before advancing to our account of the first of these parts, a few preliminary remarks are indispensable concerning the presuppositions involved in Kant"s critical work and on the method which he pursues. The presuppositions are partly psychological, partly (as the cla.s.sification of the forms of judgment and inference, and the twofold division of judgments) logical, either in the formal or the transcendental sense, and partly metaphysical (as the thing in itself). Kant takes the first of these from the psychology of his time, by combining the Wolffian cla.s.sification of the faculties with that of Tetens, and thus obtains six different faculties: lower (sensuous) and higher (intellectual) faculties of cognition, of feeling, and of appet.i.tion; or sensibility (the capacity for receiving representations through the way in which we are affected by objects), understanding (the faculty of producing representations spontaneously and of connecting them); the sensuous feelings of pleasure and pain, taste; desire, and will. The understanding in the wide sense is equivalent to the higher faculty of cognition, and divides further into understanding in the stricter sense (faculty of concepts), judgment (faculty of judging), and reason (faculty of inference). Of these the first gives laws to the faculty of cognition or to nature, the second laws to taste, and the third laws to the will.
The most important of the fundamental a.s.sumptions concerns the relation, the nature, and the mission of the two faculties of cognition. These do not differ in degree, through the possession of greater or less distinctness-for there are sensuous representations which are distinct and intellectual ones which are not so-but specifically: Sensibility is the faculty of intuitions, understanding the faculty of concepts. Intuitions are particular, concepts general representations. The former relate to objects directly, the latter only indirectly (through the mediation of other representations). In intuition the mind is receptive, in conception it acts spontaneously. "Through intuitions objects are given to us; through concepts they are thought." It results from this that neither of the two faculties is of itself sufficient for the attainment of knowledge, for cognition is objective thinking, the determination of objects, the unifying combination or elaboration of a given manifold, the forming of a material content. Rationalists and empiricists alike have been deceived in regard to the necessity for co-operation between the senses and the understanding. Sensibility furnishes the material manifold, which of itself it is not able to form, while the understanding gives the unifying form, to which of itself it cannot furnish a content. "Intuitions without concepts are blind" (formless, unintelligible), "concepts without intuitions are empty" (without content). In the one case, form and order are wanting; in the other, the material to be formed. The two faculties are thrown back on each other, and knowledge can arise only from their union.
A certain degree of form is attained in sense, it is true, since the chaos of sensations is ordered under the "forms of intuition," s.p.a.ce and time, which are an original possession of the intuiting subject, but this is not sufficient, without the aid of the understanding, for the genesis of knowledge. In view of the a priori nature of s.p.a.ce and time, though without detraction from their intuitive character (they are immediate particular representations), we may a.s.sign pure sensibility to the higher faculty of cognition and speak of an intuiting reason.
The forms of intuition and of thought come from within, they lie ready in the mind a priori, though not as completed representations. They are functions, necessary actions of the soul, for the execution of which a stimulus from without, through sensations, is necessary, but which, when once this is given, the soul brings forth spontaneously. The external impulse merely gives the soul the occasion for such productive acts, while their grounds and laws are found in its own nature. In this sense Kant terms them "originally acquired," and in the Introduction to the Critique of Pure Reason declares that although it is indubitable that "all our knowledge begins with experience (impressions of sense), yet it does not all arise from experience." That a representation or cognition is a priori[1] does not mean that it precedes experience in time, but that (apart from the merely exciting, non-productive stimulation through impressions already mentioned) it is independent of all experience, that it is not derived or borrowed from experience.
[Footnote 1: The terms a priori representation and pure representation (concept, intuition) are equivalent; but in judgments, on the other hand, there is a distinction. A judgment is a priori when the connection takes place independently of experience, no matter whether the concepts connected are a priori or not. If the former is the case the a priori judgment is pure (mixed with nothing empirical); if the latter, it is mixed.]
The material of intuition and thought is given to the soul, received by it; it arises through the action of objects upon the senses, and is always empirical. Intuition is the only organ of reality; in sensation the presence of a real object as the cause of the sensation is directly revealed. When Kant"s transcendental idealism was placed by a reviewer on a level with the empirical idealism of Berkeley, which denies the existence of the external world, he distinctly a.s.serted that it had never entered his mind to question the reality of external things. Further, after the existence of real things affecting the senses had been transformed in his mind from a basis of the investigation into an object of inquiry, he endeavored to defend this a.s.sumption (which at first he had navely borrowed from the realism of pre-scientific thought) by arguments, but without any satisfactory result.[1]
[Footnote 1: The task of confirming the existence of things in themselves changes under his hands into another, that of proving the existence of external phenomena. "That external objects are real as representations" Berkeley had never disputed.]
On the basis of the inseparability of sensibility and understanding the ideal of knowledge-an extension of knowledge to be attained by a priori means (p. 333)-experiences a remarkable addition in the position that the rational synthesis thus obtained must be a knowledge of reality, must be applied to matter given in intuition. To the question, "How are synthetic judgments a priori possible?" is joined a second equally legitimate inquiry, "How do they become objectively valid, or applicable to objects of experience?" The principle from which their validity is proved-they are applicable to objects of experience because without them experience would not be possible, because they are conditions of experience-like the criterion of apriority (strict universality and necessity), is one of the noetic a.s.sumptions of the critical theory.[1]
[Footnote 1: Cf. Vaihinger, Kommentar, i. pp. 425-430.]
Inasmuch as its investigation relates to the conditions of experience the Kantian criticism follows a method which it itself terms transcendental. Heretofore, when the metaphysical method had been adopted, the object had been the suprasensible; and when knowledge had been made the object of investigation, the method followed had been empirical, psychological. Kant had the right to consider himself the creator of noetics, for he showed it the transcendental point of view. Knowledge is an object of experience, but its conditions are not. The object is to explain knowledge, not merely to describe it psychologically,-to establish a new science of knowledge from principles, from pure reason. That which lies beyond experience is sealed from our thought; that which lies on this side of it is still uninvestigated, though capable and worthy of investigation, and in extreme need thereof. Criticism forbids the transcendent use of reason (transcending experience); it permits, demands, and itself exercises the transcendental[1] use of it, which explains an experiential object, knowledge, from its conditions, which are not empirically given.
[Footnote A: Kant applies the term transcendental to the knowledge (the discovery, the proof) of the a priori factor and its relation to objects of experience. Unfortunately he often uses the same word not only to designate the a priori element itself, but also as a synonym for transcendent. In all three cases its opposite is empirical, namely, empirico-psychological investigation by observation in distinction from noetical investigation from principles; empirical origin in distinction from an origin in pure reason, and empirical use in distinction from application beyond the limits of experience.]
There is, apparently, a contradiction between the empiristic result of the Critique of Reason (the limitation of knowledge to objects of experience) and its rationalistic proofs (which proceed metaphysically, not empirically), and, in fact, a considerable degree of opposition really exists. Kant argues in a metaphysical way that there can be no metaphysics. This contradiction is solved by the distinction which has been mentioned between that which is beyond, and that which lies within, the boundary of experience. That metaphysic is forbidden which on the objective side soars beyond experience, but that pure rational knowledge is permissible and necessary which develops from principles the grounds of experiential knowledge existing in the subject. In the Kantian school, however, these complementary elements,-empirical result, transcendental or metaphysical, properly speaking, pro-physical method,-were divorced, and the one emphasized, favored, and further developed at the expense of the other. The empiricists hold to the result, while they either weaken or completely misunderstand the rationalism of the method: the a priori factor, says Fries, was not reached by a priori, but by a posteriori, means, and there is no other way by which it could have been reached. The constructive thinkers, Fichte and his successors, adopt and continue the metaphysical method, but reject the empirical result. Fichte"s aim is directed to a system of necessary, unconscious processes of reason, among which, rejecting the thing in itself, he includes sensation. According to Sch.e.l.ling nature itself is a priori, a condition of consciousness. This discrepancy between foundation and result continues in an altered form even among contemporary thinkers-as a discussion whether the "main purpose" of Criticism is to be found in the limitation of knowledge to possible experience, or the establishment of a priori elements-though many, in adherence to Kant"s own view, maintain that the metaphysics of knowledge and of phenomena (immanent rationalism) is the only legitimate metaphysics.
1. Theory of Knowledge.
(a) The Pure Intuitions (Transcendental Aesthetic).-The first part of the Critique of Reason, the Transcendental Aesthetic, lays down the position that s.p.a.ce and time are not independent existences, not real beings, and not properties or relations which would belong to things in themselves though they were not intuited, but forms of our intuition, which have their basis in the subjective const.i.tution of our, the human, mind. If we separate from sensuous intuition all that the understanding thinks in it through its concepts, and all that belongs to sensation, these two forms of intuition remain, which may be termed pure intuitions, since they can be considered apart from all sensation. As subjective conditions (lying in the nature of the subject) through which alone a thing can become an object of intuition for us, they precede all empirical intuitions or are a priori.
s.p.a.ce and time are neither substantial receptacles which contain all that is real nor orders inhering in things in themselves, but forms of intuition. Now all our representations are either pure or empirical in their origin, and either intuitive or conceptual in character. Kant advances four proofs for the position that s.p.a.ce and time are not empirical and not concepts, but pure intuitions: (1) Time is not an empirical concept which has been abstracted from experience. For the coexistence or succession of phenomena, i.e., their existence at the same time or at different times (from which, as many believe, the representation of time is abstracted), itself presupposes time-a coexistence or succession is possible only in time. It is no less false that s.p.a.ce is abstracted from the empirical s.p.a.ce relations of external phenomena, their existence outside and beside one another, or in different places, for it is impossible to represent relative situation except in s.p.a.ce. Therefore experience does not make s.p.a.ce and time possible; but s.p.a.ce and time first of all make experience possible, the one outer, the other inner experience. They are postulates of perception, not abstractions from it. (2) Time is a necessary representation a priori. We can easily think all phenomena away from it, but we cannot remove time itself in view of phenomena in general; we can think time without phenomena, but not phenomena without time. The same is true of s.p.a.ce in reference to external objects. Both are conditions of the possibility of phenomena. (3) Time is not a discursive or general concept. For there is but one time. And different times do not precede the one time as the const.i.tuent parts of which it is made up, but are mere limitations of it; the part is possible only through the whole. In the same way the various s.p.a.ces are only parts of one and the same s.p.a.ce, and can be thought in it alone. But a representation which can be given only by a single object is a particular representation or an intuition. Because, therefore, of the oneness of s.p.a.ce and time, the representation of each is an intuition. The a priori, immediate intuition of the one s.p.a.ce is entirely different from the empirical, general conception of s.p.a.ce, which is abstracted from the various s.p.a.ces. (4) Determinate periods of time arise by limitation of the one, fundamental time. Consequently this original time must be unlimited or infinite, and the representation of it must be an intuition, not a concept. Time contains in itself an endless number of representations (its parts, times), but this is never the case with a generic concept, which, indeed, is contained as a partial representation in an endless number of representations (those of the individuals having the same name), and, consequently, comprehends them all under itself, but which never contains them in itself. The general concept horse is contained in each particular representation of a horse as a general characteristic, and that of justice in each representation of a definite just act; time, however, is not contained in the different times, but they are contained in it. Similarly the relation of infinite s.p.a.ce to the finite s.p.a.ces is not the logical relation of a concept to examples of it, but the intuitive relation of an unlimited whole to its limited parts.
The Prolegomena employs as a fifth proof for the intuitive character of s.p.a.ce, an argument which had already appeared in the essay On the Ultimate Ground of the Distinction of Positions in s.p.a.ce. There are certain spatial distinctions which can be grasped by intuition alone, and which are absolutely incapable of comprehension through the understanding-for example, those of right and left, above and below, before and behind. No logical marks can be given for the distinction between the object and its image in the mirror, or between the right ear and the left. The complete description of a right hand must, in all respects (quality, proportionate position of parts, size of the whole), hold for the left as well; but, despite the complete similarity, the one hand cannot be exactly super-imposed on the other; the glove of the one cannot be worn on the other. This difference in direction, which has significance only when viewed from a definite point, and the impossibility mentioned of a congruence between an object (right hand) and its reflected image (left hand) can be understood only by intuition; they must be seen and felt, and cannot be made clear through concepts, and, consequently, can never be explained to a being which lacks the intuition of s.p.a.ce.
In the "transcendental" exposition of s.p.a.ce and time Kant follows this "metaphysical" exposition, which had to prove their non-empirical, and non-discursive, hence their a priori and intuitive, character, with the proof that only such an explanation of s.p.a.ce and time could make it conceivable how synthetic cognitions a priori can arise from them. The principles of mathematics are of this kind. The synthetic character of geometrical truths is explained by the intuitive nature of s.p.a.ce, their apodictic character by its apriority, and their objective reality or applicability to empirical objects by the fact that s.p.a.ce is the condition of (external) perception. The like is true of arithmetic and time.
If s.p.a.ce were a mere concept, no proposition could be derived from it which should go beyond the concept and extend our knowledge of its properties. The possibility of such extension or synthesis in mathematics depends on the fact that spatial concepts can always be presented or "constructed" in intuition. The geometrical axiom that in the triangle the sum of two sides is greater than the third is derived from intuition, by describing the triangle in imagination or, actually, on the board. Here the object is given through the cognition and not before it.-If s.p.a.ce and time were empirical representations the knowledge obtained from them would lack necessity, which, as a matter of fact, it possesses in a marked degree. While experience teaches us only that something is thus or so, and not that it could not be otherwise, the axioms, (s.p.a.ce has only three dimensions, time only one; only one straight line is possible between two points), nay, all the propositions of mathematics are strictly universal and apodictically certain: we are entirely relieved from the necessity of measuring all triangles in the world in order to find out whether the sum of their angles is equal to two right angles, and we do not need, as in the case of judgments of experience, to add the limitation, so far as it is yet known there are no exceptions to this rule. The apriority is the ratio essendi of the strict necessity involved in the "it must be so" (des Soseinmussens), while the latter is the ratio cognoscendi of the former. Now since the necessity of mathematical judgments can only be explained through the ideality of s.p.a.ce, this doctrine is perfectly certain, not merely a probable hypothesis.-The validity of mathematical principles for all objects of perception, finally, is based on the fact that they are rules under which alone experience is possible for us. It should be mentioned, further, that the conceptions of change and motion (change of place) are possible only through and in the representation of time. No concept could make intelligible the possibility of change, that is, of the connection of contradictory predicates in one and the same thing, but the intuition of succession easily succeeds in accomplishing it.
The argument is followed by conclusions and explanations based upon it; (1) s.p.a.ce is the form of the outer, time of the inner, sense. Through the outer sense external objects are given to us, and through the inner sense our own inner states. But since all representations, whether they have external things for their objects or not, belong in themselves, as mental determinations, to our inner state, time is the formal condition of all phenomena in general, directly of internal (psychical) phenomena, and, thereby, indirectly of external phenomena also. (2) The validity of the relations of s.p.a.ce and time cognizable a priori is established for all objects of possible experience, but is limited to these. They are valid for all phenomena (for all things which at any time may be given to our senses), but only for these, not for things as they are in themselves. They have "empirical reality, but, at the same time, transcendental ideality." As external phenomena all things are beside one another in s.p.a.ce, and all phenomena whatever are in time and of necessity under temporal relations; in regard to all things which can occur in our experience, and in so far as they can occur, s.p.a.ce and time are objectively, therefore empirically, real. But they do not possess absolute reality (neither subsistent reality nor the reality of inherence); for if we abstract from our sensuous intuition both vanish, and, apart from the subject (N.B., the transcendental subject, concerning which more below), they are naught. It is only from man"s point of view that we can speak of s.p.a.ce, and of extended, moveable, changeable things; for we can know nothing concerning the intuitions of other thinking beings, we have no means of discovering whether they are bound by the same conditions which limit our intuitions, and which for us are universally valid. (3) Nothing which is intuited in s.p.a.ce is a thing in itself. What we call external objects are nothing but mere representations of our sensibility, whose true correlative, the thing in itself, cannot be known by ever so deep penetration into the phenomenon; such properties as belong to things in themselves can never be given to us through the senses. Similarly nothing that is intuited in time is a thing in itself, so that we intuit ourselves only as we appear to ourselves, and not as we are.
The merely empirical reality of s.p.a.ce and time, the limitation of their validity to phenomena, leaves the certainty of knowledge within the limits of experience intact; for we are equally certain of it, whether these forms necessarily belong to things in themselves, or only to our intuitions of things. The a.s.sertion of their absolute reality, on the other hand, involves us in sheer absurdities (that is, it necessitates the a.s.sumption of two infinite nonent.i.ties which exist, but without being anything real, merely in order to comprehend all reality, and on one of which even our own existence would be dependent), in view of which the origin of so peculiar a theory as the idealism of Berkeley appears intelligible. The critical theory of s.p.a.ce and time is so far from being identical with, or akin to, the theory of Berkeley, that it furnishes the best and only defense against the latter. If anyone a.s.sumes the absolute or transcendental reality of these forms, it is impossible for him to prevent everything, including even our own existence, from being changed thereby into mere illusion. But the critical philosopher is far from degrading bodies to mere illusion; external phenomena are just as real for him as internal phenomena, though only as phenomena, it is true, as (possible) representations.
Phenomenon and illusion are not the same. The transcendental distinction between phenomena and things in themselves must not be confused with the distinction common to ordinary life and to physics, in accordance with which we call the rainbow a mere appearance (better, illusion), but the combination of sun and rain which gives rise to this illusion the thing in itself, as that which in universal experience and in all different positions with respect to the senses, is thus and not otherwise determined in intuition, or that which essentially belongs to the intuition of the object, and is valid for every human sensibility (in ant.i.thesis to that which only contingently belongs to it, and is valid only for a special position or organization of this or that sense). Similarly an object always appears to grow smaller as its distance increases, while in itself it is and remains of some fixed size. And this use of words is perfectly correct, in the physical or empirical sense of "in itself"; but in the transcendental sense the raindrops, also, together with their form and size, are themselves mere phenomena, the "in itself" of which remains entirely unknown to us. Kant, moreover, does not wish to see the subjectivity of the forms of intuition placed on a level with the subjectivity of sensations or explained by this, though he accepts it as a fact long established. The sensations of color, of tone, of temperature are, no doubt, like the representation of s.p.a.ce in that they belong only to the subjective const.i.tution of the sensibility, and can be attributed to objects only in relation to our senses. But the great difference between the two is that these sense qualities may be different in different persons (the color of the rose may seem different to each eye), or may fail to harmonize with any human sense; that they are not a priori in the same strict sense as s.p.a.ce and time, and consequently afford no knowledge of the objects of possible experience independently of perception; and that they are connected with the phenomenon only as the contingently added effects of a particular organization, while s.p.a.ce, as the condition of external objects, necessarily belongs to the phenomenon or intuition of them. It is through s.p.a.ce alone that it is possible for things to be external objects for us. The subjectivity of sensation is individual, while that of s.p.a.ce and time is general or universal to mankind; the former is empirical, individually different, and contingent, the latter a priori and necessary. s.p.a.ce alone, not sensation, is a conditio sine qua non of external perception. s.p.a.ce and time are the sole a priori elements of the sensibility; all other sensuous concepts, even motion and change, presuppose perception; the movable in s.p.a.ce and the succession of properties in an existing thing are empirical data.
In confirmation of the theory that all objects of the senses are mere phenomena, the fact is adduced that (with the exception of the will and the feelings, which are not cognitions) nothing is given us through the senses but representations of relations, while a thing in itself cannot be known by mere relations. The phenomenon is a sum total of mere relations. In regard to matter we know only extension, motion, and the laws of this motion or forces (attraction, repulsion, impenetrability), but all these are merely relations of the thing to something, else, that is, external relations. Where is the inner side which underlies this exterior, and which belongs to the object in itself? This is never to be found in the phenomenon, and no matter how far the observation and a.n.a.lysis of nature may advance (a work with unlimited horizons!) they reach nothing but portions of s.p.a.ce occupied by matter and effects which matter exercises, that is, nothing beyond that which is comparatively internal, and which, in its turn, consists of external relations. The absolutely inner side of matter is a mere fancy; and if the complaint that the "inner side" of things is concealed from us is to mean that we do not comprehend what the things which appear to us may be in themselves, it is unjust and irrational, for it demands that we should be able to intuit without senses, in other words, that we should be other than men. The transcendent questions concerning the noumenon of things are unanswerable; we know ourselves, even, only as phenomena! A phenomenon consists in nothing but the relation of something in general to the senses.
It is indubitable that something corresponds to phenomena, which, by affecting our sensibility, occasions sensations in us, and thereby phenomena. The very word, the very concept, "phenomenon", indicates a relation to something which is not phenomenon, to an object not dependent on the sensibility. What this may be continues hidden from us, for knowledge is impossible without intuition. Things in themselves are unknowable. Nevertheless the idea (it must be confessed, the entirely empty idea) of this "transcendental object", as an indeterminate somewhat = x which underlies phenomena, is not only allowable, but, as a limiting concept, unavoidable in order to confine the pretensions of sense to the only field which is accessible to it, that is, to the field of phenomena.
The inference "s.p.a.ce and time are nothing but representations and representations are in us, therefore s.p.a.ce and time as well as all phenomena in them, bodies with their forces and motions, are in us," does not accurately express Kant"s position, for he might justly reply that, according to him, bodies as phenomena are in different parts in s.p.a.ce from that which we a.s.sign to ourselves, and thus without us; that s.p.a.ce is the form of external intuition, and through it external objects arise for us from sensations; but that, in regard to the things in themselves which affect us, we are entirely ignorant whether they are within or without us.
It can easily be shown by literal quotations that there were distinct tendencies in Kant, especially in the first edition of his princ.i.p.al work, toward a radical idealism which doubts or denies not merely the cognizability, but also the existence of objects external to the subject and its representations, and which degrades the thing in itself to a mere thought in us, or completely does away with it (e.g., "The representation of an object as a thing in general is not only insufficient, but, ... independently of empirical conditions, in itself contradictory "). But these expressions indicate only a momentary inclination toward such a view, not a binding avowal of it, and they are outweighed by those in which idealism is more or less energetically rejected. That which according to Kant exists outside the representation of the individual is twofold: (1) the unknown things in themselves with their problematical characteristics, as the ground of phenomena; (2) the phenomena "themselves" with their knowable immanent laws, and their relations in s.p.a.ce and time, as possible representations. When I turn my glance away from the rose its redness vanishes, since this predicate belongs to it only in so far and so long as it acts in the light on my visual apparatus. What, then, is left? That thing in itself, of course, which, when it appears to me, calls forth in me the intuition of the rose. But there is still something else remaining-the phenomenon of the rose, with its size, its form, and its motion in the wind. For these are predicates which must be attributed to the phenomenon itself as the object of my representation. If the rose, as determined in s.p.a.ce and time, vanished when I turned my head away, it could not, unless intuited by a subject, experience or exert effects in s.p.a.ce and time, could not lose its leaves in the wind and strew the ground with its petals. Perception and thought inform me not merely concerning events of which I am a witness, but also of others which have occurred, or which will occur, in my absence. The process of stripping the leaves from the rose has actually taken place as a phenomenon and does not first become real by my subsequent representation of it or inference to it. The things and events of the phenomenal world exist both before and after my perception, and are something distinct from my subjective and momentary representations of them. The s.p.a.ce and time, however, in which they exist and happen are not furnished by the intuiting individual, but by the supra-individual, transcendental consciousness or generic reason of the race. The phenomenon thus stands midway between its objective ground (the absolute thing in itself) and the subject, whose common product it is, as a relative thing in itself, as a reality which is independent of the contingent and changing representation of the individual, empirical subject, which is dependent for its form on the transcendental subject, and which is the only reality accessible to us, yet entirely valid for us. The phenomenal world is not a contingent and individual phenomenon, but one necessary for all beings organized as we are, a phenomenon for humanity. My representations are not the phenomena themselves, but images and signs through which I cognize phenomena, i.e., real things as they are for me and for every man (not as they are in themselves). The reality of phenomena consists in the fact that they can be perceived by men, and the objective validity of my knowledge of them in the fact that every man must agree in it. The laws which the understanding (not the individual understanding!) imposes upon nature hold for phenomena, because they hold for every man. Objectivity is universal validity. If the world of phenomena which is intuited and known by us wears a different appearance from the world of things in themselves, this does not justify us in declaring it to be mere seeming and dreaming; a dream which all dream together, and which all must dream, is not a dream, but reality. As we must represent the world> so it is, though for us, of course, and not in itself.
Many places in Kant"s works seem to argue against the intermediate position here ascribed to the world of phenomena-according to which it is less than things in themselves and more than subjective representation-which, since they explain the phenomenon as a mere representation, leave room for only two factors (on the one hand, the thing in itself = that in the thing which cannot be represented; on the other, the thing for me = my representation of the thing). In fact, the distinction between the phenomenon "itself" and the representation which the individual now has of it and now does not have, is far from being everywhere adhered to with desirable clearness; and wherever it is impossible to subst.i.tute that which has been represented and that which may be represented or possible intuitions for "mere representations in me," we must acknowledge that there is a departure from the standpoint which is a.s.sumed in some places with the greatest distinctness. The latter finds unequivocal expression, among other places, in the "a.n.a.logies of Experience" and the "Deduction of the Pure Concepts of the Understanding," -- 2, No. 4 (first edition). The second of these pa.s.sages speaks of one and the same universal experience, in which all perceptions are represented in thoroughgoing and regular connection, and of the thoroughgoing affinity of phenomena as the basis of the possibility of the a.s.sociation of representations. This affinity is ascribed to the objects of the senses, not to the representations, whose a.s.sociation is rather the result of the affinity, and not to the things in themselves, in regard to which the understanding has no legislative power.
The relation between the thing in itself and the phenomenon is also variable. Now they are regarded as entirely heterogeneous (that which can never be intuited exists in a mode opposed to that of the intuited and intuitable), and now as a.n.a.logous to each other (non-intuitable properties of the thing in itself correspond to the intuitable characteristics of the phenomenon). The former is the case when it is said that phenomena are in s.p.a.ce and time, while things in themselves are not; that in the first of these cla.s.ses natural causation rules, and in the second freedom; that in the one-conditioned existence alone is found, in the other unconditioned.[1] But just as often things in themselves and phenomena are conceived as similar to one another, as two sides of the same object,[2] of which one, like the counter-earth of the Pythagoreans, always remains turned away from us, while the other is turned toward us, but does not reveal the true being of the object. According to this each particular thing, state, relation, and event in the world of phenomena would have its real counterpart in the noumenal sphere: un-extended roses in themselves would lie back of extended roses, certain non-temporal processes back of their growth and decay, intelligible relations back of their relations in s.p.a.ce. This is approximately the relation of the two conceptions as in part taught by Lotze himself, in part represented by him as taught by Kant. Herbart"s principle, "So much seeming, so much indication of being" (wie viel Schein so viel Hindeutung aufs Sein), might also be cited in this connection. That which continually impelled Kant, in spite of his proclamation of the unknowableness of things in themselves, to form ideas about their character, was the moral interest, but this sometimes threw its influence in favor of their commensurability with phenomena and sometimes in the opposite scale. For in his ethics Kant needs the intelligible character or man as noumenon, and must a.s.sume as many men in themselves (to be consistent, then, in general, as many beings in themselves) as there are in the world of phenomena. But for practical reasons, again, the causality of the man in himself must be thought of as entirely different from, and opposed to, the mechanical causality of the sense world. Kant"s judgment is, also, no more stable concerning the value of the knowledge of the suprasensible, which is denied to us. "I do not need to know what things in themselves may be, because a thing can never be presented to me otherwise than as a phenomenon." And yet a natural and ineradicable need of the reason to obtain some conviction in regard to the other world is said to underlie the abortive attempts of metaphysics; and Kant himself uses all his efforts to secure to the practical reason the satisfaction of this need, though he has denied it to the speculative reason, and to make good the gap in knowledge by faith. From the theoretical standpoint an extension of knowledge beyond the limits of phenomena appears impossible, but unnecessary; from the practical standpoint it is, to a certain extent, possible and indispensable.
[Footnote 1: Kant"s conjectures concerning a common ground of material and mental phenomena, and those concerning the common root of sensibility and understanding, show the same tendency. On the one hand, duality, on the other, unity.]
[Footnote 2: "Phenomenon, which always has two sides, the one when the object in itself is considered (apart from the way in which it is intuited, and just because of which fact its character always remains problematical), the other when we regard the form of the intuition of this object, which must be sought not in the object in itself, but in the subject to whom the object appears, while it nevertheless actually and necessarily belongs to the phenomenon of this object." "This predicate "-sc., spatial quality, extension-"is attributed to things only in so far as they appear to us."]
There is, then, a threefold distinction to be made: (1) Things in themselves, which can never be the object of our knowledge, because our forms of intuition are not valid for them. (2) Phenomena, things for us, nature or the totality of that which either is or, at least, may be the object of our knowledge (here belong the possible inhabitants of the moon, the magnetic matter which pervades all bodies, and the forces of attraction and repulsion, though the first have never been observed, and the second is not perceptible on account of the coa.r.s.eness of our senses, and the last, because forces in general are not perceptible; nature comprehends everything whose existence "is connected with our perceptions in a possible experience"[1]). (3) Our representations of phenomena, i.e., that of the latter which actually enters into the consciousness of the empirical individual. In the realm of things in themselves there is no motion whatever, but at most an intelligible correlate of this relation; in the world of phenomena, the world of physics, the earth moves around the sun; in the sphere of representation the sun moves around the earth. It is true, as has been said, that Kant sometimes ignores the distinction between phenomena as related to noumena and phenomena as related to representations; and, as a result of this, that the phenomenon is either completely volatilized into the representation[2] or split up into an objective half independent of us and a representative half dependent on us, of which the former falls into the thing in itself,[3] while the latter is resolved into subjective states of the ego.
[Footnote 1: "Nothing is actually given to us but the perception and the empirical progress from this to other possible perceptions." "To call a phenomenon a real thing antecedent to perception, means ... that in the progress of experience we must meet with such a perception."]
[Footnote 2: Phenomena "are altogether in me," "exist only in our sensibility as a modification of it." "There is nothing in s.p.a.ce but that which is actually represented in it." Phenomena are "mere representations, which, if they are not given in us (in perception) nowhere exist."]
[Footnote 3: Here Kant is guilty of the fault which he himself has censured, of confusing the physical and transcendental meanings of "in itself." He forgets that the thing, if it is momentarily not intuited or represented by me, and therefore is not immediately given for me as an individual, is nevertheless still present for me as man, is mediately given, that is, is discoverable by future search. That which is without my present consciousness is not for this reason without all human consciousness. In fact, Kant often overlooks the distinction between actual and possible intuition, so that for him the "objects" of the latter slip out of s.p.a.ce and time and into the thing in itself. To the "transcendental object we may ascribe the extent and connection of our possible perceptions, and say that it is given in itself before all experience." In it "the real things of the past are given."]
After the possibility and the legitimacy of synthetic judgments a priori have been proved for pure mathematics upon the basis of the pure intuitions, there emerges, in the second place, the problem of the possibility of a priori syntheses in pure natural science, or the question, Do pure concepts exist? And after this has been answered in the affirmative, the further questions come up, Is the application of these, first, to phenomena, and second, to things in themselves, possible and legitimate, and how far?
(b) The Concepts and Principles of the Pure Understanding (Transcendental a.n.a.lytic).-Sensations, in order to become "intuition" or the perception of a phenomenon, needed to be ordered in s.p.a.ce and time; in order to become "experience" or a unified knowledge of objects, intuitions need a synthesis through concepts. In order to objective knowledge the manifold of intuition (already ordered by its arrangement in s.p.a.ce and time) must be connected in the unity of the concept. Sensibility gives the manifold to be connected, the understanding the connecting unity. The former is able to intuit only, the latter only to think; knowledge can arise only as the result of their union. Intuitions depend on affections, concepts on functions, that is, on unifying acts of the understanding.
To discover the pure forms of thought it is necessary to isolate the understanding, just as an isolation of the sensibility was necessary above in order to the discovery of the pure forms of intuition. We obtain the elements of the pure knowledge of the understanding by rejecting all that is intuitive and empirical. These elements must be pure, must be concepts, further, not derivative or composite, but fundamental concepts, and their number must be complete. This completeness is guaranteed only when the pure concepts or categories are sought according to some common principle, which a.s.signs to each its position in the connection of the whole, and not (as with Aristotle) collected by occasional, unsystematic inquiries undertaken at random. The table of the forms of judgment will serve as a guide for the discovery of the categories. Thought is knowledge through concepts; the understanding can make no other use of concepts than to judge by means of them. Hence, since the understanding is the faculty of judging, the various kinds of connection in judgment must yield the various pure "connective-concepts" (Verknupfungsbegriffe.-K. Fischer) or categories.
In regard to quant.i.ty, every judgment is universal, particular, or singular; in regard to quality, affirmative, negative, or infinite; in regard to relation, categorical, hypothetical, or disjunctive; and in regard to modality, problematical, a.s.sertory, or apodictic. To these twelve forms of judgment correspond as many categories, viz., I., Unity, Plurality, Totality; II., Reality, Negation, Limitation; III., Subsistence and Inherence (Substance and Accident), Causality and Dependence (Cause and Effect), Community (Reciprocity between the Active and the Pa.s.sive); IV., Possibility-Impossibility, Existence-Non-existence, Necessity-Contingency.
The first six of these fundamental concepts, which have no correlatives, const.i.tute the mathematical, the second six, which appear in pairs, the dynamical categories. The former relate to objects of (pure or of empirical) intuition, the latter to the existence of these objects (in relation to one another or to the understanding). Although all other a priori division though concepts must be dichotomous, each of the four heads includes three categories, the third of which in each case arises from the combination of the second and first,[1] but, nevertheless, is an original (not a derivative) concept, since this combination requires a special actus of the understanding. Universality or totality is plurality regarded as unity, limitation is reality combined with negation, community is the reciprocal causality of substances, and necessity is the actuality given by possibility itself. Kant omits, as unnecessary here, the useful, easy, and not unpleasant task of noting the great number of derivative concepts a priori (predicables) which spring from the combination of these twelve original concepts (predicaments = categories) with one another, or with the modes of pure sensibility,-the concepts force, action, pa.s.sion, would belong as subsumptions under causality, presence and resistance under community, origin, extinction, and change under modality,-since his object is not a system, but only the principles of one. His liking or even love for this division according to quant.i.ty, quality, relation, and modality, which he always has ready as though it were a universal key for philosophical problems, reveals a very strong architectonic impulse, against which even his ever active skeptical tendency is not able to keep up the battle.
[Footnote 1: Concerning this "neat observation," Kant remarked that it might "perhaps have important consequences in regard to the scientific form of all knowledge of reason." This prophecy was fulfilled, although in a different sense from that which floated before his mind. Fichte and Hegel composed their "thought-symphonies" in the three-four time given by Kant.]
In view of the derivation of the forms of thought from the forms of judgment Kant does not stop to give a detailed proof that the categories are concepts, and that they are pure. Their discursive (not intuitive) character is evident from the fact that their reference to the object is mediate only (and not, as in the case of intuition, immediate), and their a priori origin, from the necessity which they carry with them, and which would be impossible if their origin were empirical. Here Kant starts from Hume"s criticism of the idea of cause. The Scottish skeptic had said that the necessary bond between cause and effect can neither be perceived nor logically demonstrated; that, therefore, the relation of causality is an idea which we-with what right?-add to perceived succession in time. This doubt (without the hasty conclusions), says Kant, must be generalized, must be extended to the category of substance (which had been already done by Hume, pp. 226-7, though the author of the Critique of Reason was not aware of the fact), and to all other pure concepts of the understanding. Then we may hope to kindle a torch at the spark which Hume struck out. The problem "It is impossible to see why, because something exists, something else must necessarily exist," is the starting point alike of Hume"s skepticism and Kant"s criticism. The former recognized that the principle of causality is neither empirical nor a.n.a.lytic, and therefore concluded that it is an invention of reason, which confuses subjective with objective necessity. The latter shows that in spite of its subjective origin it has an objective value; that it is a truth which is independent of all experience, and yet valid for all who have experience, and for all that can be experienced.
Of the two questions, "How can the concepts which spring from our understanding possess objective validity?" and, "How (through what means or media) does their application to objects of experience take place?" the first is answered in the Deduction of the Pure Concepts of the Understanding, and the second in the chapter on their Schematism.
The Deduction, the most difficult portion of the Critique, shows that the objective validity of the categories, as concepts of objects in general, depends on the fact that through them alone experience as far as regards the form of thought _is possible, i.e., it is only through them that any object whatever can be thought. All knowledge consists in judgments; all judgments contain a connection of representations; all connection-whether it be conscious or not, whether it relates to concepts or to pure or empirical intuitions-is an act of the understanding; it cannot be given by objects, but only spontaneously performed by the subject itself. We cannot represent anything as connected in the object unless we have ourselves first connected it. The connection includes three conceptions: that of the manifold to be connected (which is given by intuition), that of the act of synthesis, and that of the unity; this last is two-fold, an objective unity (the conception of an object in general in which the manifold is united), and a subjective unity (the unity of consciousness under which or, rather, through which the connection is effected). The categories represent the different kinds of combination, each one of these, again, being completed in three stages, which are termed the Synthesis of Apprehension in Intuition, the Synthesis of Reproduction in Imagination, and the Synthesis of Recognition in Concepts. If I wish to think the time from one noon to the next, I must (1) grasp (apprehend) the manifold representations (portions of time) in succession; (2) retain or renew (reproduce) in thought those which have preceded in pa.s.sing to those which follow; (3) be conscious that that which is now thought is the same with that thought before, or know again (recognize) the reproduced representation as the one previously experienced. If the mind did not exercise such synthetic activity the manifold of representation would not const.i.tute a whole, would lack the unity which consciousness alone can impart to it. Without this one consciousness, concepts and knowledge of objects would be wholly impossible. The unity of pure self-consciousness or of "transcendental apperception" is the postulate of all use of the understanding. In the flux of internal phenomena there is no constant or abiding self, but the unchangeable consciousness here demanded is a precedent condition of all experience, and gives to phenomena a connection according to laws which determine an object for intuition, i.e., the conception of something in which they are necessarily connected.[1] Reference to an object is nothing other than the necessary unity of consciousness. The connective activity of the understanding, and with it experience, is possible only through "the synthetic unity of pure apperception," the "I think," which must be able to accompany all my representations, and through which they first become mine.
[Footnote 1: Object is "that which opposes the random or arbitrary determination of our cognitions," and which causes "them to be determined in a certain way a priori."]
Experience (in the strict sense) is distinguished from perception (experience in the wide sense) by its objectivity or universal validity. A judgment of perception (the sun shines upon the stone and the stone becomes warm) is only subjectively valid; while, on the other hand, a judgment of experience (the sun warms the stone) aims to be valid not only for me and my present condition, but always, for me and for everyone else. If the former is to become the latter, an a priori concept must be added to the perception (in the above case, the concept of cause), under which the perception is subsumed. The category determines the perceptions in view of the form of the judgment, gives to the judgment its reference to an object, and thus gives to the percepts, or rather, concepts (sunshine and warmth), necessary and universally valid connection. The "reason why the judgments of others" must "agree with mine" is "the unity of the object to which they all relate, with which they agree, and hence must also all agree with one another."