To this, however, we have to add the other great mistake, that, certainly according to the procedure of earlier philosophy, he has confounded the conceptions of necessity and contingency with each other. That earlier philosophy has applied abstraction to the following mistaken use. It was clear that that of which the reason is given inevitably follows, _i.e._, cannot not be, and thus necessarily is. But that philosophy held to this last determination alone, and said that is necessary which cannot be otherwise, or the opposite of which is impossible. It left, however, the ground and root of such necessity out of account, overlooked the relativity of all necessity which follows from it, and thereby made the quite unthinkable fiction of an _absolute necessity_, _i.e._, of something the existence of which would be as inevitable as the consequent of a reason, but which yet was not the consequent of a reason, and therefore depended upon nothing; an addition which is an absurd _petitio_, for it conflicts with the principle of sufficient reason. Now, starting from this fiction, it explained, in diametrical opposition to the truth, all that is established by a reason as contingent, because it looked at the relative nature of its necessity and compared this with that entirely imaginary _absolute_ necessity, which is self-contradictory in its conception.(5) Now Kant adheres to this fundamentally perverse definition of the contingent and gives it as explanation. (Critique of Pure Reason, V. p. 289-291, 243. V. 301, 419. V. 447, 486, 488.) He falls indeed into the most evident contradiction with himself upon this point, for on p. 301 he says: “Everything contingent has a cause,” and adds, “That is contingent which might possibly not be.” But whatever has a cause cannot possibly not be: thus it is necessary. For the rest, the source of the whole of this false explanation of the necessary and the contingent is to be found in Aristotle in “_De Generatione et Corruptione_,” lib. ii. c. 9 et 11, where the necessary is explained as that which cannot possibly not be: there stands in opposition to it that which cannot possibly be, and between these two lies that which can both be and not be,—thus that which comes into being and passes away, and this would then be the contingent. In accordance with what has been said above, it is clear that this explanation, like so many of Aristotle’s, has resulted from sticking to abstract conceptions without going back to the concrete and perceptible, in which, however, the source of all abstract conceptions lies, and by which therefore they must always be controlled. “Something which cannot possibly not be” can certainly be thought in the abstract, but if we go with it to the concrete, the real, the perceptible, we find nothing to support the thought, even as possible,—as even merely the asserted consequent of a given reason, whose necessity is yet relative and conditioned.