Critique of Pure Reason

by Immanuel Kant

  It is true nevertheless that, in order to admit anything, it is not enough that there should be no positive impediment to it, nor are we allowed to introduce fictions of our thoughts, transcending all our concepts, though contradicting none, as real and definite objects, on the mere credit of our somewhat perfunctory speculative reason. They should not therefore be admitted as real in themselves, but their reality should only be considered as the reality of a schema of a regulative principle for the systematical unity of all natural knowledge. Hence they are to be admitted as analoga only of real things, and not as real things in themselves. We remove from the object of an idea the conditions which limit the concepts of our understanding, and which alone enable us to have a definite concept of anything; and then we represent to ourselves a something of which we know not in the least what it is by itself, but which, nevertheless, we represent to ourselves in a relation to the whole of phenomena, analogous to that relation which phenomena have among themselves.

  If therefore we admit such ideal beings, we do not really enlarge our knowledge beyond the objects of possible experience, but only the empirical unity of those objects, by means of that systematical unity of which the idea furnishes us the schema, and which therefore cannot claim to be a constitutive, but only a regulative principle. For if we admit a something, or a real being, corresponding to the idea, we do not intend thereby to enlarge our knowledge of things by means of transcendental11 concepts; for such a being is admitted in the idea only, and not by itself, and only in order to express that systematical unity which is to guide the empirical use of our reason, without stating anything as to what is the ground of that unity or the internal nature of such a being on which, as its cause, that unity depends.

  Thus the transcendental and the only definite concept which purely speculative reason gives us of God is in the strictest sense deistic; that is, reason does not even supply us with the objective validity of such a concept, but only with the idea of something on which the highest and necessary unity of all empirical reality is founded, and which we cannot represent to ourselves except in analogy with a real substance, being, according to the laws of nature, the cause of all things; always supposing that we undertake to think it at all as a particular object, and, satisfied with the mere idea of the regulative principle of reason, do not rather put aside the completion of all the conditions of our thought, as too much for the human understanding, which, however, is hardly compatible with that perfect systematical unity of our knowledge to which reason at least imposes no limits.

  Thus it happens that, if we admit a Divine Being, we have not the slightest conception either of the internal possibility of its supreme perfection, nor of the necessity of its existence, but are able at least thus to satisfy all other questions relating to contingent things, and give the most perfect satisfaction to reason with reference to that highest unity in its empirical application that has to be investigated, but not in reference to that hypothesis itself. This proves that it is the speculative interest of reason, and not its real insight, which justifies it in starting from a point so far above its proper sphere, in order to survey from thence its objects, as belonging to a complete whole.

  Here we meet with a distinction in our mode of thought, the premisses remaining the same, a distinction which is somewhat subtle, but of great importance in transcendental philosophy. I may have sufficient ground for admitting something relatively (suppositio relative), without having a right to admit it absolutely (suppositio absoluta). This distinction comes in when we have to deal with a regulative principle, of which we know the necessity by itself, but not the source of this necessity, and where we admit a supreme cause, only in order to think the universality of the principle with greater definiteness. Thus, if I think of a being as existing which corresponds to a mere idea, and to a transcendental one, I ought not to admit the existence of such a being by itself, because no concepts through which I can conceive any object definitely, can reach it, and the conditions of the objective validity of my concepts are excluded by the idea itself. The concepts of reality, of substance, even of causality, and those of necessity in existence, have no meaning that could determine any object, unless they are used to make the empirical knowledge of an object possible. They may be used, therefore, to explain the possibility of things in the world of sense, but not to explain the possibility of a universe itself, because such an hypothesis is outside the world and could never be an object of possible experience. I can, however, admit perfectly well such an inconceivable Being, being the object of a mere idea, relative to the world of sense, though not as existing by itself. For if the greatest possible empirical use of my reason depends on an idea (on the systematically complete unity of which I shall soon speak more in detail), which by itself can never be adequately represented in experience, though it is indispensably necessary in order to bring the empirical unity as near as possible to the highest perfection, I shall not only have the right, but even the duty, to realise such an idea, that is, to assign to it a real object, though only as a something in general, which by itself I do not know at all, and to which, as the cause of that systematical unity, I ascribe, in reference to it, such qualities as are analogous to the concepts employed by the understanding in dealing with experience. I shall, therefore, according to the analogy of realities in the world, of substances, of causality, and of necessity, conceive a Being possessing all these in the highest perfection, and, as this idea rests on my reason only, conceive that Being as self-subsistent reason, being, through the ideas of the greatest harmony and unity, the cause of the universe. In doing this I omit all conditions which could limit the idea, simply in order to render, with the help of such a fundamental cause, the systematical unity of the manifold in the universe, and, through it, the greatest possible empirical use of reason, possible. I then look upon all connections in the world as if they were ordered by a supreme reason, of which our own reason is but a faint copy, and I represent to myself that Supreme Being through concepts which, properly speaking, are applicable to the world of sense only. As, however, I make none but a relative use of that transcendental hypothesis, as the substratum of the greatest possible unity of experience, I may perfectly well represent a Being which I distinguish from the world, by qualities which belong to the world of sense only. For I demand by no means, nor am I justified in demanding, that I should know that object of my idea, according to what it may be by itself. I have no concepts whatever for it, and even the concepts of reality, substance, causality, ay, of the necessity in existence, lose all their meaning, and become mere titles of concepts, void of contents, as soon as I venture with them outside the field of the senses. I only present to myself the relation of a Being, utterly unknown to me as existing by itself, to the greatest possible systematical unity of the universe, in order to use it as a schema of the regulative principle of the greatest possible empirical use of my reason.

  If now we glance at the transcendental object of our idea, we find that we cannot, according to the concepts of reality, substance, causality, etc., presuppose its reality by itself, because such concepts are altogether inapplicable to something totally distinct from the world of sense. The supposition, therefore, which reason makes of a Supreme Being, as the highest cause, is relative only, devised for the sake of the systematical unity in the world of sense, and a mere Something in the idea, while we have no concept of what it may be by itself. Thus we are able to understand why we require the idea of an original Being, necessary by itself, with reference to all that is given to the senses as existing, but can never have the slightest conception of it and of its absolute necessity.

  At this point we are able to place the results of the whole transcendental Dialectic clearly before our eyes, and to define accurately the final aim of the ideas of pure reason, which could become dialectical through misapprehension and carelessness only. Pure reason is, in fact, concerned with nothing but itself, nor can it have any other occupation, because what is given to it are not the objects i
ntended for the unity of an empirical concept, but the knowledge supplied by the understanding for the unity of the concept of reason, that is, of its connection according to a principle. The unity of reason is the unity of a system, and that systematical unity does not serve objectively as a principle of reason to extend its sway over objects, but subjectively as a maxim to extend its sway over all possible empirical knowledge of objects. Nevertheless, the systematical connection which reason can impart to the understanding in its empirical use helps not only to extend that use, but confirms at the same time its correctness; nay, the principle of such systematical unity is objective also, though in an indefinite manner (principium vagum), not as a constitutive principle, determining something in its direct object, but only as a regulative principle and maxim, advancing and strengthening infinitely (indefinitely), the empirical use of reason by the opening of new paths unknown to the understanding, without ever running counter to the laws of its practical use.

  Reason, however, cannot think this systematical unity, without attributing to its idea an object, which, as experience has never given an example of complete systematical unity, can never be given in any experience. This Being, demanded by reason (ens rationis ratiocinatae), is no doubt a mere idea, and not therefore received as something absolutely real and real by itself. It is only admitted problematically (for we cannot reach it by any concepts of the understanding), in order to enable us to look upon the connection of things in the world of sense, as if they had their ground in that being, the real intention being to found upon it that systematical unity which is indispensable to reason, helpful in every way to the empirical knowledge of the understanding, and never a hindrance to it.

  We misapprehend at once the true meaning of that idea, if we accept it as the assertion, or even as the hypothesis of a real thing to which the ground of the systematical construction of the world should be ascribed. What we ought to do is to leave it entirely uncertain, what that ground which escapes all our concepts may be by itself, and to use the idea only as a point of view from which alone we may expand that unity which is as essential to reason as beneficial to the understanding. In one word, that transcendental thing is only the schema of the regulative principle with which reason spreads systematical unity, as far as possible, over all experience.

  The first object of such an idea is the ego, considered merely as a thinking nature (soul). Now if I want to know the qualities with which a thinking being exists in itself, I have to consult experience: but of all the categories, I cannot apply a single one to that object, unless its schema is given in sensuous intuition. Thus, however, I can never arrive at a systematical unity of all the phenomena of the internal sense. Reason, therefore, instead of taking from experience the concept of that which the soul is in reality, which would not lead us very far, prefers the concept of the empirical unity of all thought, and by representing that unity as unconditioned and original, it changes it into a concept of reason, or an idea of a simple substance, a substance unchangeable in itself (personally identical), and in communication with other real things outside it; in one word, into a simple self-subsistent intelligence. In doing this, its object is merely to find principles of systematical unity for the explanation of the phenomena of the soul, so that all determinations may be received as existing in one subject, all powers, as much as possible, as derived from one fundamental power, and all changes as belonging to the states of one and the same permanent being, while all phenomena in space are represented as totally different from the acts of thought. That simplicity of substance, etc., was only meant to be the schema of this regulative principle; it is not assumed to be the real ground of all the properties of the soul. These properties may rest on quite different grounds, of which we know nothing; nor could we know the soul even by these assumed predicates by itself, even if we regarded them as absolutely valid with regard to it, for they really constitute a mere idea which cannot be represented in concreto. Nothing but good can spring from such a psychological idea, if only we take care not to take it for more than an idea, that is, if we apply it only in relation to the systematical use of reason, with reference to the phenomena of our soul. For in that case no empirical laws of corporeal phenomena, which are of a totally different kind, are mixed up with the explanation of what belongs to the internal sense; and no windy hypothesis of generation, extinction, and palingenesis of souls are admitted. The consideration of this object of the internal sense remains pure and unmixed with heterogeneous matters, while reason in its investigations is directed towards tracing all the grounds of explanation, as far as possible, to one single principle; and this can best be achieved, nay, cannot be achieved otherwise but by such a schema which attributes to the soul hypothetically the character of a real being. The psychological idea cannot be anything but such a schema of a regulative concept. The very question, for instance, whether the soul by itself be of a spiritual nature, would have no meaning, because, by such a concept, I should take away not only corporeal, but all nature, that is, all predicates of any possible experience, and therefore all the conditions under which the object of such a concept could be thought; and, in that case, the concept would have no meaning at all.

  The second regulative idea of speculative reason is the concept of the universe. For nature is really the only object given to us in regard to which reason requires regulative principles. Nature, however, is twofold, either thinking or corporeal. In order to think the internal possibility of the latter, that is, in order to determine the application of the categories to it, we require no idea, that is, no representation which transcends experience. Nor is such an idea possible in regard to it, because we are here guided by sensuous intuition only, different from what it was in the case of the psychological fundamental concept of the I, which contains a priori a certain form of thought, namely, the unity of the I. There remains therefore for pure reason nothing to deal with but nature in general, and the completeness of its conditions according to some principle. The absolute totality of the series of these conditions determining the derivation of all their members, is an idea which, though never brought to perfection in the empirical use of reason, may yet become a rule, telling us how to proceed in the explanation of given phenomena (whether in an ascending or descending line), namely, as if the series were in themselves infinite, that is, in indefinitum; while, when reason itself is considered as the determining cause (in freedom), in the case of practical principles therefore, we must proceed as if we had to deal, not with an object of the senses, but with one of the pure understanding. Here the conditions are no longer placed within the series of phenomena, but outside it, and the series of states considered, as if it had an absolute beginning through an intelligible cause. All this proves that cosmological ideas are nothing but regulative principles, and by no means constitutive, as establishing a real totality of such series. The remainder of this argument may be seen in its place, namely, in the chapter on the Antinomy of Pure Reason.

  The third idea of pure reason, containing a merely relative hypothesis of a Being which is the only and all-sufficient cause of all cosmological series, is the idea of God. We have not the slightest ground to admit absolutely the object of that idea (to suppose it in itself); for what could enable, or even justify us in believing or asserting a Being of the highest perfection, and absolutely necessary from its very nature, on the strength of its concept only, except the world with reference to which alone such an hypothesis may be called necessary? We then perceive that the idea of it, like all speculative ideas, means no more than that reason requires us to consider all connection in the world according to the principles of a systematical unity, and, therefore, as if the whole of it had sprung from a single all-embracing Being, as its highest and all-sufficient cause. We see, therefore, that reason can have no object here but its own formal rule in the extension of its empirical use, but can never aim at extension beyond all limits of its empirical application. This idea, therefore, does not involve a constitutive principle of its us
e as applied to possible experience.

  The highest formal unity, which is based on concepts of reason alone, is the systematical and purposeful unity of things, and it is the speculative interest of reason which makes it necessary to regard all order in the world as if it had originated in the purpose of a supreme wisdom. Such a principle opens to our reason in the field of experience quite new views, how to connect the things of the world according to teleological laws, and thus to arrive at their greatest systematical unity. The admission of a highest intelligence, as the only cause of the universe, though in the idea only, can therefore always benefit reason, and yet never injure it. For if, with regard to the figure of the earth (which is round, though somewhat flattened12), of mountains, and seas, etc., we admit at once nothing but wise intentions of their author, we are enabled to make in this wise a number of important discoveries. If we keep to this hypothesis as a purely regulative principle, even error cannot hurt us much; for the worst that could happen would be that, when we expected a teleological connection (nexus finalis), we only find a mechanical or physical (nexus effectivus), in which case we merely lose an additional unity, but we do not destroy the unity of reason in its empirical application. And even this failure could not affect the law itself, in its general and teleological character. For although an anatomist may be convicted of error, if referring any member of an animal body to a purpose of which it can clearly be shown that it does not belong to it, it is entirely impossible in any given case to prove that an arrangement of nature, be it what it may, has no purpose at all. Medical physiology, therefore, enlarges its very limited empirical knowledge of the purposes of the members of an organic body by a principle inspired by pure reason only, so far as to admit confidently, and with the approbation of all intelligent persons, that everything in an animal has its purpose and advantage. Such a supposition, if used constitutively, goes far beyond where our present observation would justify us in going, which shows that it is nothing but a regulative principle of reason, leading us on to the highest systematical unity, by the idea of an intelligent causality in the supreme cause of the world, and by the supposition that this, as the highest intelligence, is the cause of everything, according to the wisest design.