Critique of Pure Reason

by Immanuel Kant

  Supplement XII

  § 11

  This table of categories suggests some interesting considerations, which possibly may have important consequences with regard to the scientific form of all knowledge of reason. For it is clear that such a table will be extremely useful, nay, indispensable, in the theoretical part of philosophy, in order to trace the complete plan of a whole science, so far as it rests on concepts a priori, and to divide it systematically according to fixed principles, because that table contains all elementary concepts of the understanding in their completeness, nay, even the form of a system of them in the human understanding, and indicates therefore all the momenta of a projected speculative science, nay, even their order. Of this I have given an example elsewhere.12 Here follow some of the considerations.

  The first is, that this table, which contains four classes of the concepts of the understanding, may, in the first instance, be divided into two sections, the former of which refers to objects of intuition (pure, as well as empirical), the latter to the existence of those objects (either in their relation to each other, or to the understanding).

  The first section I shall call that of the mathematical, the second, that of the dynamical categories. The first section has no correlates, which are met with in the second section only. Must not this difference have some ground in the nature of the understanding?

  Our second remark is, that in every class there is the same number of categories, namely three, which again makes us ponder, because generally all division a priori by means of concepts must be dichotomy. It should be remarked also, that the third category always arises from the combination of the second with the first. Thus totality is nothing but plurality considered as unity; limitation nothing but reality connected with negation; community is the casualty of a substance as determining another reciprocally; lastly, necessity, the existence which is given by possibility itself. It must not be supposed, however, that therefore the third category is only a derivative, and not a primary concept of the pure understanding. For the joining of the first and second concepts, in order to produce the third, requires an independent act of the understanding, which is not identical with the act that produces the first and second concepts. Thus the concept of a number (which belongs to the category of totality) is not always possible when we have the concepts of plurality and unity (for instance, in the concept of the infinite); nor can we understand by simply combining the concept of a cause and that of a substance, the influence, that is, how a substance can become the cause of something in another substance. This shows that a separate act of the understanding is here required, and the same applies to all the rest.

  Third observation. With regard to one category, namely, that of community, which is found in the third class, its accordance with the form of a disjunctive judgment, which corresponds to it in the table of logical functions, is not so evident as elsewhere.

  In order to become quite certain of that accordance, we must remark that in all disjunctive judgments their sphere (that is, all that is contained in them) is represented as a whole, divided into parts (the subordinate concepts), and that, as one of them cannot be contained under the other, they are conceived as co-ordinate, not as subordinate, determining each other, not in one direction only, as in a series, but reciprocally, as in an aggregate (if one member of the division is given, all the rest are excluded, and vice versa).

  A similar connection is conceived in a whole of things, in which one, as effect, is not subordinated to another as the cause of its existence, but is co-ordinated with it, simultaneously and reciprocally, as cause of the determination of the other (as, for instance, in a body of which the parts reciprocally attract and repel each other). This is a kind of connection totally different from that which exists in a mere relation of cause to effect (of ground to consequence), for here the consequence does not reciprocally determine the ground again, nor (as in the case of the Creator and the creation) constitute with it a whole. The process of the understanding, in representing to itself the sphere of a divided concept, is the same as that by which it thinks a thing as divisible: and in the same manner in which, in the former, the members of a division exclude each other, and are yet connected in one sphere, the understanding represents to itself the parts of the latter as existing (as substances), each independent of the rest, and yet united in a whole.

  § 12

  In the transcendental philosophy of the ancients there is another chapter containing concepts of the understanding which, though they are not counted among the categories, are yet considered by them as concepts a priori of objects. If so, they would increase the number of the categories, which cannot be. They are set forth in the famous proposition of the Schoolmen, 'quodlibet ens est unum, verum, bonum.' Now, although the inferences to be drawn from this principle (yielding nothing but tautological propositions) were very meagre, so that modern metaphysicians mention it almost by courtesy only, a thought which has maintained itself so long, however empty it may seem, deserves an investigation with regard to its origin, nay, leads us to suspect that it may have its foundation in some rule of the understanding which, as often happens, has only been wrongly interpreted. What are supposed to be transcendental predicates of things are nothing but logical requirements and criteria of all knowledge of things in general, whereby that knowledge is founded on the categories of quantity, namely, unity, plurality, and totality. Only, instead of taking them as materially belonging to the possibility of things by themselves, they (the predicates, or rather those who employed them) used them, in fact, in their formal meaning only, as forming a logical requisite for every kind of knowledge, and yet incautiously made these criteria of thought to be properties of the things by themselves. In every cognition of an object there is unity of concept, which may be called qualitative unity, so far as we think by it only the unity in the comprehension of the manifold material of our knowledge: as, for instance, the unity of the subject in a play, or a speech, or a fable. Secondly, there is truth, in respect to the deductions from it. The more true deductions can be made from a given concept, the more criteria are there of its objective reality. This might be called the qualitative plurality of criteria, which belong to a concept as their common ground (but are not conceived in it, as quantity). Thirdly, there is completeness, which consists in this, that the plurality together leads back to the unity of the concept, according completely with this and with no other concept, which may be called the qualitative completeness (totality). This shows that these logical criteria of the possibility of knowledge in general do nothing but change the three categories of quantity, in which the unity in the production of the quantum must throughout be taken as homogeneous, for the purpose of connecting heterogeneous elements of knowledge also in one consciousness, by means of the quality of the cognition as the principle of the connection. Thus the criterion of the possibility of a concept (but not of its object) is the definition of it, in which the unity of the concept, the truth of all that may be immediately deduced from it, and lastly, the completeness of what has been deduced from it, supply all that is necessary for the constitution of the whole concept. In the same manner the criterion of an hypothesis consists, first, in the intelligibility of the ground which has been admitted for the sake of explanation, or of its unity (without any auxiliary hypothesis); secondly, in the truth of the consequences to be deduced from it (their accordance with themselves and with experience); and lastly, in the completeness of the ground admitted for the explanation of these consequences, which point back to neither more nor less than what was admitted in the hypothesis, and agree in giving us again, analytically a posteriori, what had been thought synthetically a priori. The concepts of unity, truth, and perfection, therefore, do not supplement the transcendental table of the categories, as if it were imperfect, but they serve only, after the relation of these concepts to objects has been entirely set aside, to bring their employment under general logical rules, for the agreement of knowledge with itself.

  Supp
lement XIII

  Locke, for want of this reflection, and because he met with pure concepts of the understanding in experience, derived them also from experience, and yet acted so inconsistently that he attempted to use them for knowledge which far exceeds all limits of experience. David Hume saw that, in order to be able to do this, these concepts ought to have their origin a priori; but as he could not explain how it was possible that the understanding should be constrained to think concepts, which by themselves are not united in the understanding, as necessarily united in the object, and never thought that possibly the understanding might itself, through these concepts, be the author of that experience in which its objects are found, he was driven by necessity to derive them from experience (namely, from a subjective necessity, produced by frequent association in experience, which at last is wrongly supposed to be objective, that is, from habit). He acted, however, very consistently, by declaring it to be impossible to go with these concepts, and with the principles arising from them, beyond the limits of experience. This empirical deduction, which was adopted by both philosophers, cannot be reconciled with the reality of our scientific knowledge a priori, namely, pure mathematics and general natural science, and is therefore refuted by facts. The former of these two celebrated men opened a wide door to fantastic extravagance, because reason, if it has once established such pretensions, can no longer be checked by vague praises of moderation; the other, thinking that he had once discovered so general an illusion of our faculty of knowledge, which had formerly been accepted as reason, gave himself over entirely to scepticism. We now intend to make the experiment whether it is not possible to conduct reason safely between these two rocks, to assign to her definite limits, and yet to keep open for her the proper field for all her activities?

  I shall merely premise an explanation of what I mean by the categories. They are concepts of an object in general by which its intuition is regarded as determined with reference to one of the logical functions in judgments. Thus the function of the categorical judgment was that of the relation of the subject to the predicate; for instance, all bodies are divisible. Here, however, with reference to the pure logical employment of the understanding, it remained undetermined to which of the two concepts the function of the subject, or the predicate, was to be assigned. For we could also say, some divisible is body. But by bringing the concept of body under the category of substance, it is determined that its empirical intuition in experience must always be considered as subject and never as predicate only. The same applies to all other categories.

  Supplement XIV

  Of The Deduction of the Pure Concepts of the Understanding

  Second Section

  Transcendental Deduction of the Pure Concepts of the Understanding

  § 15

  Of the Possibility of Connecting (conjunctio) in General

  The manifold of representations may be given in an intuition which is purely sensuous, that is, nothing but receptivity, and the form of that intuition may lie a priori in our faculty of representation, without being anything but the manner in which a subject is affected. But the connection (conjunctio) of anything manifold can never enter into us through the senses, and cannot be contained, therefore, already in the pure form of sensuous intuition, for it is a spontaneous act of the power of representation; and as, in order to distinguish this from sensibility, we must call it understanding, we see that all connecting, whether we are conscious of it or not, and whether we connect the manifold of intuition or several concepts together, and again, whether that intuition be sensuous or not sensuous, is an act of the understanding. This act we shall call by the general name of synthesis, in order to show that we cannot represent to ourselves anything as connected in the object, without having previously connected it ourselves, and that of all representations connection is the only one which cannot be given through the objects, but must be carried out by the subject itself, because it is an act of its spontaneity. It can be easily perceived that this act must be originally one and the same for every kind of connection, and that its dissolution, that is, the analysis, which seems to be its opposite, does always presuppose it. For where the understanding has not previously connected, there is nothing for it to disconnect, because, as connected, it could only be given by the understanding to the faculty of representation.

  But the concept of connection includes, besides the concept of the manifold and the synthesis of it, the concept of the unity of the manifold also. Connection is representation of the synthetical unity of the manifold.13

  The representation of that unity cannot therefore be the result of the connection; on the contrary, the concept of the connection becomes first possible by the representation of unity being added to the representation of the manifold. And this unity, which precedes a priori all concepts of connection, must not be mistaken for that category of unity of which we spoke on p. 68; for all categories depend on logical functions in judgments, and in these we have already connection, and therefore unity of given concepts. The category, therefore, presupposes connection, and we must consequently look still higher for this unity as qualitative (see Suppl. XII. § 12), in that, namely, which itself contains the ground for the unity of different concepts in judgments, that is, the ground for the very possibility of the understanding, even in its logical employment.

  § 16

  The Original Synthetical Unity of Apperception

  It must be possible that the I think should accompany all my representations: for otherwise something would be represented within me that could not be thought, in other words, the representation would either be impossible or nothing, at least so far as I am concerned. That representation which can be given before all thought, is called intuition, and all the manifold of intuition has therefore a necessary relation to the I think in the same subject in which that manifold of intuition is found. That representation, however (that I think), is an act of spontaneity, that is, it cannot be considered as belonging to sensibility. I call it pure apperception, in order to distinguish it from empirical apperception, or original apperception also, because it is that self-consciousness which by producing the representation, I think (which must accompany all others, and is one and the same in every act of consciousness), cannot itself be accompanied by any other. I also call the unity of it the transcendental unity of self-consciousness, in order to indicate that it contains the possibility of knowledge a priori.

  For the manifold representations given in any intuition would not all be my representations, if they did not all belong to one self-consciousness. What I mean is that, as my representations (even though I am not conscious of them as such), they must be in accordance with that condition, under which alone they can stand together in one common self-consciousness, because otherwise they would not all belong to me. From this original connection the following important conclusions can be deduced.

  The unbroken identity of apperception of the manifold that is given in intuition contains a synthesis of representations, and is possible only through the consciousness of that synthesis. The empirical consciousness, which accompanies various representations, is itself various and disunited, and without reference to the identity of the subject. Such a relation takes place, not by my simply accompanying every relation with consciousness, but by my adding one to the other and being conscious of that act of adding, that is, of that synthesis. Only because I am able to connect the manifold of given representations in one consciousness, is it possible for me to represent to myself the identity of the consciousness in these representations, that is, only under the supposition of some synthetical unity of apperception does the analytical unity of apperception become possible.14

  The thought that the representations given in intuition belong all of them to me, is therefore the same as that I connect them in one self-consciousness, or am able at least to do so; and though this is not yet the consciousness of the synthesis of representations, it nevertheless presupposes the possibility of this synthesis. In other words, it i
s only because I am able to comprehend the manifold of representations in one consciousness, that I call them altogether my representations, for otherwise, I should have as manifold and various a self as I have representations of which I am conscious. The synthetical unity of the manifold of intuitions as given a priori is therefore the ground also of the identity of that apperception itself which precedes a priori all definite thought. Connection, however, does never lie in the objects, and cannot be borrowed from them by perception, and thus be taken into the understanding, but it is always an act of the understanding, which itself is nothing but a faculty of connecting a priori, and of bringing the manifold of given representations under the unity of apperception, which is, in fact, the highest principle of all human knowledge.

  It is true, no doubt, that this principle of the necessary unity of apperception is itself identical, and therefore an analytical proposition; but it shows, nevertheless, the necessity of a synthesis of the manifold which is given in intuition, without which synthesis it would be impossible to think the unbroken identity of self-consciousness. For through the Ego, as a simple representation, nothing manifold is given; in the intuition, which is different from that, it can be given only, and then, by connection, be thought in one consciousness. An understanding in which, by its self-consciousness, all the manifold would be given at the same time, would possess intuition; our understanding can do nothing but think, and must seek for its intuition in the senses. I am conscious, therefore, of the identical self with respect to the manifold of the representations, which are given to me in an intuition, because I call them, altogether, my representations, as constituting one. This means, that I am conscious of a necessary synthesis of them a priori, which is called the original synthetical unity of apperception under which all representations given to me must stand, but have to be brought there, first, by means of a synthesis.