Critique of Pure Reason

by Immanuel Kant

  We can easily perceive that although the same spaces are perfectly filled by two different kinds of matter, so that there is no point in either of them where matter is not present, yet the real in either, the quality being the same, has its own degrees (of resistance or weight) which, without any diminution of its extensive quantity, may grow smaller and smaller in infinitum, before it reaches the void and vanishes. Thus a certain expansion which fills a space, for instance, heat, and every other kind of phenomenal reality, may, without leaving the smallest part of space empty, diminish by degrees in infinitum, and nevertheless fill space with its smaller, quite as much as another phenomenon with greater degrees. I do not mean to say that this is really the case with different kinds of matter according to their specific of gravity. I only want to show by a fundamental principle of the pure understanding, that the nature of our perceptions renders such an explanation possible, and that it is wrong to look upon the real in phenomena as equal in degree, and differing only in aggregation and its extensive quantity, nay to maintain this on the pretended authority of an a priori principle of the understanding.

  Nevertheless, this anticipation of perception is apt to startle5 an enquirer accustomed to and rendered cautious by transcendental disquisitions, and we may naturally wonder that the understanding should be able to anticipate⊃2; a synthetical proposition with regard to the degree of all that is real in phenomena, and, therefore, with regard to the possibility of an internal difference of sensation itself, apart from its empirical quality; and it seems therefore a question well worthy of a solution, how the understanding can pronounce synthetically and a priori about phenomena, nay, anticipate them with regard to what, properly speaking, is empirical, namely, sensation.

  The quality of sensation, colour, taste, etc., is always empirical, and cannot be conceived a priori. But the real that corresponds to sensations in general, as opposed to negation = 0, does only represent something the concept of which implies being, and means nothing but the synthesis in any empirical consciousness. In the internal sense that empirical consciousness can be raised from o to any higher degree, so that an extensive quantity of intuition (for instance, an illuminated plain) excites the same amount of sensation, as an aggregate of many other less illuminated plains. It is quite possible, therefore, to take no account of the extensive quantity of a phenomenon, and yet to represent to oneself in the mere sensation in any single moment a synthesis of a uniform progression from o to any given empirical consciousness. All sensations, as such, are therefore given a posteriori6 only, but their quality, in so far as they must possess a degree, can be known a priori. It is remarkable that of quantities in general we can know one quality only a priori, namely, their continuity, while with regard to quality (the real of phenomena) nothing is known to us a priori, but their intensive quantity, that is, that they must have a degree. Everything else is left to experience.

  III

  [The Analogies of Experience

  The general principle of them is: All phenomena, as far as their existence is concerned, are subject a priori to rules, determining their mutual relation in one and the same time⊃2;]

  The three modi of time are permanence, succession, and coexistence. There will therefore be three rules of all relations of phenomena in time, by which the existence of every phenomenon with regard to the unity of time is determined, and these rules will precede all experience, nay, render experience possible.

  The general principle of the three analogies depends on the necessary unity of apperception with reference to every possible empirical consciousness (perception) at every time, and, consequently, as that unity forms an a priori ground, on the synthetical unity of all phenomena, according to their relation in time. For the original apperception refers to the internal sense (comprehending all representations), and it does so a priori to its form, that is, to the relation of the manifold of the empirical consciousness in time. The original apperception is intended to combine all this manifold according to its relations in time, for this is what is meant by its transcendental unity a priori, to which all is subject which is to belong to my own and my uniform knowledge, and thus to become an object for me. This synthetical unity in the time relations of all perceptions, which is determined a priori, is expressed therefore in the law, that all empirical determinations of time must be subject to rules of the general determination of time; and the analogies of experience, of which we are now going to treat, are exactly rules of this kind.

  These principles have this peculiarity, that they do not refer to phenomena and the synthesis of their empirical intuition, but only to the existence of phenomena and their mutual relation with regard to their existence. The manner in which something is apprehended as a phenomenon may be so determined a priori that the rule of its synthesis may give at the same time this intuition a priori in any empirical case, nay, may really render it possible. But the existence of phenomena can never be known a priori, and though we might be led in this way to infer some kind of existence, we should never be able to know it definitely, or to anticipate that by which the empirical intuition of one differs from that of others.

  The principles which we considered before and which, as they enable us to apply mathematics to phenomena, I called mathematical, refer to phenomena so far only as they are possible, and showed how, with regard both to their intuition and to the real in their perception, they can be produced according to the rules of a mathematical synthesis, so that, in the one as well as in the other, we may use numerical quantities, and with them a determination of all phenomena as quantities. Thus I might, for example, compound the degree of sensations of the sunlight out of, say, 200,000 illuminations by the moon, and thus determine it a priori or construct it. Those former principles might therefore be called constitutive.

  The case is totally different with those principles which are meant to bring the existence of phenomena under rules a priori, for as existence cannot be constructed, they can only refer to the relations of existence and become merely regulative principles. Here therefore we could not think of either axioms or anticipations, and whenever a perception is given us as related in time to some others (although undetermined), we could not say a priori what other perception or how great a perception is necessarily connected with it, but only how, if existing, it is necessarily connected with the other in a certain mode of time. In philosophy analogy means something very different to what it does in mathematics. In the latter they are formulas which state the equality of two quantitative relations, and they are always constitutive so that when three7 terms of a proposition are given, the fourth also is given by it, that is, can be constructed out of it. In philosophy, on the contrary, analogy does not consist in the equality of two quantitative, but of two qualitative relations, so that when three terms are given I may learn from them a priori the relation to a fourth only, but not that fourth term itself. All I can thus gain is a rule according to which I may look in experience for the fourth term, or a characteristic mark by which I may find it. An analogy of experience can therefore be no more than a rule according to which a certain unity of experience may arise from perceptions (but not how perception itself, as an empirical intuition, may arise); it may serve as a principle for objects (as phenomena8) not in a constitutive, but only in a regulative capacity.

  Exactly the same applies to the postulates of empirical thought in general, which relate to the synthesis of mere intuition (the form of phenomena), the synthesis of perception (the matter of them), and the synthesis of experience (the relation of these perceptions). They too are regulative principles only, and differ from the mathematical, which are constitutive, not in their certainty, which is established in both a priori, but in the character of their evidence, that is, in that which is intuitive in it, and therefore in their demonstration also.

  What has been remarked of all synthetical principles and must be enjoined here more particularly is this, that these analogies have their meaning and validity, not as principles of the transcen
dent, but only as principles of the empirical use of the understanding. They can be established in this character only, nor can phenomena ever be comprehended under the categories directly, but only under their schemata. If the objects to which these principles refer were things by themselves, it would be perfectly impossible to know anything of them a priori and synthetically. But they are nothing but phenomena, and our whole knowledge of them, to which, after all, all principles a priori must relate, is only our possible experience of them. Those principles therefore can aim at nothing but the conditions of the unity of empirical knowledge in the synthesis of phenomena, which synthesis is represented only in the schema of the pure concepts of the understanding, while the category contains the function, restricted by no sensuous condition, of the unity of that synthesis as synthesis in general. Those principles will therefore authorise us only to connect phenomena, according to analogy, with the logical and universal unity of concepts, so that, though in using the principle we use the category, yet in practice (in the application to phenomena) we put the schema of the category, as a practical key, in its9 place, or rather put it by the side of the category as a restrictive condition, or, as what may be called, a formula of the category.

  A

  [First Analogy

  Principle of Permanence10

  All phenomena contain the permanent (substance) as the object itself, and the changeable as its determination only, that is, as a mode in which the object exists

  Proof of the First Analogy

  All phenomena take place in time. Time can determine in two ways the relation in the existence of phenomena, so far as they are either successive or coexistent. In the first case time is considered as a series, in the second as a whole.]

  Our apprehension of the manifold of phenomena is always successive, and therefore always changing. By it alone therefore we can never determine whether the manifold, as an object of experience, is coexistent or successive, unless there is something in it which exists always, that is, something constant and permanent, while change and succession are nothing but so many kinds (modi) of time in which the permanent exists. Relations of time are therefore possible in the permanent only (coexistence and succession being the only relations of time) so that the permanent is the substratum of the empirical representation of time itself, and in it alone all determination of time is possible. Permanence expresses time as the constant correlative of all existence of phenomena, of all change and concomitancy. For change does not affect time itself, but only phenomena in time (nor is coexistence a mode of time itself, because in it no parts can be coexistent, but successive only). If we were to ascribe a succession to time itself, it would be necessary to admit another time in which such succession should be possible. Only through the permanent does existence in different parts of a series of time assume a quantity which we call duration. For in mere succession existence always comes and goes, and never assumes the slightest quantity. Without something permanent therefore no relation of time is possible. Time by itself, however, cannot be perceived, and it is therefore the permanent in phenomena that forms the substratum for all determination of time, and at the same time the condition of the possibility of all synthetical unity of perceptions, that is, of experience; while with regard to that permanent all existence and all change in time can only be taken as a mode of existence of what is permanent. In all phenomena therefore the permanent is the object itself, that is, the substance (phenomenon), while all that changes or can change belongs only to the mode in which substance or substances exist, therefore to their determinations.

  I find that in all ages not only the philosopher, but also the man of common understanding has admitted this permanence as a substratum of all change of phenomena. It will be the same in future, only that a philosopher generally expresses himself somewhat more definitely by saying that in all changes in the world the substance remains, and only the accidents change. But I nowhere find even the attempt at a proof of this very synthetical proposition, and it occupies but seldom that place which it ought to occupy at the head of the pure and entirely a priori existing laws of nature. In fact the proposition that substance is permanent is tautological, because that permanence is the only ground why we apply the category of substance to a phenomenon, and it ought first to have been proved that there is in all phenomena something permanent, while the changeable is only a determination of its existence. But as such a proof can never be given dogmatically and as deduced from concepts, because it refers to a synthetical proposition a priori, and as no one ever thought that such propositions could be valid only in reference to possible experience, and could therefore be proved only by a deduction of the possibility of experience, we need not wonder that, though it served as the foundation of all experience (being felt to be indispensable for every kind of empirical knowledge), it has never been established by proof.

  A philosopher was asked, What is the weight of smoke? He replied, Deduct from the weight of the wood burnt the weight of the remaining ashes, and you have the weight of the smoke. He was therefore convinced that even in fire matter (substance) does not perish, but that its form only suffers a change. The proposition also, from nothing comes nothing, was only another conclusion from the same principle of permanence, or rather of the constant presence of the real subject in phenomena. For if that which people call substance in a phenomenon is to be the true substratum for all determination in time, then all existence in the past as well as the future must be determined in it, and in it only. Thus we can only give to a phenomenon the name of substance because we admit its existence at all times, which is not even fully expressed by the word permanence, because it refers rather to future time only. The internal necessity however of permanence is inseparably connected with the necessity to have been always, and the expression may therefore stand. Gigni de nihilo nihil, in nihilum nil posse reverti, were two propositions which the ancients never separated, but which at present are sometimes parted, because people imagine that they refer to things by themselves, and that the former might contradict the dependence of the world on a Supreme Cause (even with regard to its substance), an apprehension entirely needless, as we are only speaking here of phenomena in the sphere of experience, the unity of which would never be possible, if we allowed that new things (new in substance) could ever arise. For in that case we should lose that which alone can represent the unity of time, namely, the identity of the substratum, in which alone all change retains complete unity. This permanence, however, is nothing but the manner in which we represent the existence of things (as phenomenal).

  The different determinations of a substance, which are nothing but particular modes in which it exists, are called accidents. They are always real, because they concern the existence of a substance (negations are nothing but determinations which express the non-existence of something in the substance). If we want to ascribe a particular kind of existence to these real determinations of the substance, as, for instance, to motion, as an accident of matter, we call it inherence, in order to distinguish it from the existence of substance, which11 we call subsistence. This, however, has given rise to many misunderstandings, and we shall express ourselves better and more correctly, if we define the accident through the manner only in which the existence of a substance is positively determined. It is inevitable, however, according to the conditions of the logical use of our understanding, to separate, as it were, whatever can change in the existence of a substance, while the substance itself remains unchanged, and to consider it in its relation to that which is radical and truly permanent. Hence a place has been assigned to this category under the title of relations, not so much because it contains itself a relation, as because it contains their condition.

  On this permanence depends also the right understanding of the concept of change. To arise and to perish are not changes of that which arises or perishes. Change is a mode of existence, which follows another mode of existence of the same object. Hence whatever changes is permanent, and its condition onl
y changes. As this alteration refers only to determinations which may have an end or a beginning, we may use an expression that seems somewhat paradoxical and say: the permanent only (substance) is changed, the changing itself suffers no change, but only an alteration, certain determinations ceasing to exist, while others begin.

  It is therefore in substances only that change can be perceived. Arising or perishing absolutely, and not referring merely to a determination of the permanent can never become a possible perception, because it is the permanent only which renders the representations of a transition from one state to another, from not being to being, possible, which (changes) consequently can only be known empirically, as alternating determinations of what is permanent. If you suppose that something has an absolute beginning, you must have a moment of time in which it was not. But with what can you connect that moment, if not with that which already exists? An empty antecedent time cannot be an object of perception. But if you connect this beginning with things which existed already and continue to exist till the beginning of something new, then the latter is only a determination of the former, as of the permanent. The same holds good with regard to perishing, for this would presuppose the empirical representation of a time in which a phenomenon exists no longer.

  Substances therefore (as phenomena) are the true substrata of all determinations of time. If some substances could arise and others perish, the only condition of the empirical unity of time would be removed, and phenomena would then be referred to two different times, in which existence would pass side by side, which is absurd. For there is but one time in which all different times must be placed, not as simultaneous, but as successive.