Immanuel Kant's Critique of Pure Reason — trans. F. Max Müller

Thirdly, how, when there are several things, something could follow from the existence of one of them as affecting the rest, and vice versa, so that there should exist, in this way, a certain community of substances. The same applies to the other categories, as, for instance, how a thing could be of the same kind as many others, and thus be a quantity. So long as there is no intuition, we do not know whether by the categories we conceive an object, nay, whether any object can at all belong to them : and thus we see again that by themselves the categories are not knowledge, but mere fo7'ms of thought, by which given intuitions are turned into knowledge.

It hkewise follows from this, that no synthetical proposition can be made out of mere categories, as, for instance, if it is said that in everything existing there is substance, i.e. something that can

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exist as subject only, and not as a mere predicate ; or, everything is a quantum, etc. Here we have really nothing whatever which would enable us to go beyond a given concept, and to connect with it another. Hence no one has ever succeeded in proving a synthetical proposition by pure concepts of the understanding only : as, for instance, the proposition that everything which exists contingently, has a cause.

All that could be proved was, that, without such a relation, we could not conceive the existence of what is contingent, that is, that we could not know a priori through the understanding the existence of such a thing ; from which it does not follow in the least that the same condition appUes to the possibility of things themselves.

If the reader will go back to our proof of the principle of causality, he will perceive that we could prove it of objects of possible experience only, by saying that everything which happens (every event) presupposes a cause. We could prove it only as the principle of the possibility of experience, that is, of the knoivledge of an object, given in empirical intuition^ but not by means of mere concepts.

It is perfectly true, that nevertheless this proposition, that everything contingent must have a cause, carries conviction to everybody from mere concepts : but it should be observed, that in this case the concept of the contingent contains no longer the category of modality (as something the non-existence of which can be conceived), but that of relation (as something which can only exist as the consequence of something else).

It thus becomes in reality an identical proposition, namely, that that which can exist as a consequence only has its cause. And thus, when we have to give examples of contingent existence, we have always recourse to changes^ and not only to the possibility of conceiving the opposite} Change, however, is an event which, as such, is

1 It is easy enough to conceive the non-existence of matter, but the ancients did not infer from this its contingency. Not even the change of being and notbeing of any given state of a thing, which constitutes all change, can prove the contingency of that state, as if from the reality of its opposite. The rest of a body, for instance, following on its motion, does not yet prove the contingency of that motion, because the former is the opposite of the latter. The opposite here is opposed to the other, not realiter, but logically only. In order to prove

784 Supplement XXII possible through a cause only, and the non-existence of which is therefore possible in itself. We thus mean by contingency, that something can exist as the effect of a cause only ; and if therefore a thing is assumed to be contingent, it becomes a merely analytical proposition to say that it has a cause.

It is still more remarkable, however, that, in order to understand the possibility of things according to the categories, and thus to establish the objective reality of the latter, we require not only intuitions, but always external intuitions. Thus, if we take, for instance, the pure concepts of relation, we find that : —

First, in order to give something permanent in intuition, corresponding to the concept of substance (and thus to show the objective reality of that concept), we require an intuition in space (of matter), because space alone can determine anything as permanent, while time, and therefore everything that exists in the internal sense, is in a constant flux.