The Critique of Practical Reason [51]
physical necessity, in opposition to the same notion as freedom, concerns only the existence of things so far as it is determinable in time, and, consequently, as phenomena, in opposition to their causality as things in themselves. Now if we take the attributes of existence of things in time for attributes of things in themselves (which is the common view), then it is impossible to reconcile the necessity of the causal relation with freedom; they are contradictory. For from the former it follows that every event, and consequently every action that takes place at a certain point of time, is a necessary result of what existed in time preceding. Now as time past is no longer in my power, hence every action that I perform must be the necessary result of certain determining grounds which are not in my power, that is, at the moment in which I am acting I am never free. Nay, even if I assume that my whole existence is independent on any foreign cause (for instance, God), so that the determining principles of my causality, and even of my whole existence, were not outside myself, yet this would not in the least transform that physical necessity into freedom. For at every moment of time I am still under the necessity of being determined to action by that which is not in my power, and the series of events infinite a parte priori, which I only continue according to a pre-determined order and could never begin of myself, would be a continuous physical chain, and therefore my causality would never be freedom. If, then, we would attribute freedom to a being whose existence is determined in time, we cannot except him from the law of necessity as to all events in his existence and, consequently, as to his actions also; for that would be to hand him over to blind chance. Now as this law inevitably applies to all the causality of things, so far as their existence is determinable in time, it follows that if this were the mode in which we had also to conceive the existence of these things in themselves, freedom must be rejected as a vain and impossible conception. Consequently, if we would still save it, no other way remains but to consider that the existence of a thing, so far as it is determinable in time, and therefore its causality, according to the law of physical necessity, belong to appearance, and to attribute freedom to the same being as a thing in itself. This is certainly inevitable, if we would retain both these contradictory concepts together; but in application, when we try to explain their combination in one and the same action, great difficulties present themselves which seem to render such a combination impracticable. When I say of a man who commits a theft that, by the law of causality, this deed is a necessary result of the determining causes in preceding time, then it was impossible that it could not have happened; how then can the judgement, according to the moral law, make any change, and suppose that it could have been omitted, because the law says that it ought to have been omitted; that is, how can a man be called quite free at the same moment, and with respect to the same action in which he is subject to an inevitable physical necessity? Some try to evade this by saying that the causes that determine his causality are of such a kind as to agree with a comparative notion of freedom. According to this, that is sometimes called a free effect, the determining physical cause of which lies within the acting thing itself, e.g., that which a projectile performs when it is in free motion, in which case we use the word freedom, because while it is in flight it is not urged by anything external; or as we call the motion of a clock a free motion, because it moves its hands itself, which therefore do not require to be pushed by external force; so although the actions of man are necessarily determined by causes which precede in time, we yet call them free, because these causes are ideas produced by our own faculties, whereby desires are evoked on occasion of circumstances, and hence actions are wrought according to our own pleasure.