a syringe in a great fire. I have already noticed above how Kant considered it a special merit of his moral law that it is founded solely on abstract, pure _a priori_ conceptions, consequently on =pure reason=; whereby its validity obtains (he says) not only for men, but for all rational beings as such. All the more must we regret that pure, abstract conceptions _a priori_, without real contents, and without any kind of empirical basis can never move, at any rate, men; of other rational beings I am of course incapable of speaking. The second defect, then, in Kant's ethical basis is its lack of real substance. So far this has escaped notice, because the real nature of his foundation has in all probability been thoroughly understood only by an exceedingly small number of those who were its enthusiastic propagandists. The second fault, I repeat, is entire want of reality, and hence of possible efficacy. The structure floats in the air, like a web of the subtlest conceptions devoid of all contents; it is based on nothing, and can therefore support nothing, and move nothing. And yet Kant loaded it with a burden of enormous weight, namely, the hypothesis of the Freedom of the Will. In spite of his oft declared conviction that freedom in human action has absolutely no place; that theoretically not even its possibility is thinkable (_Kritik der Praktischen Vernunft_, p. 168; R., p. 223); that, if the character of a man, and all the motives which work on him were exactly known, his conduct could be calculated as certainly and as precisely as an eclipse of the moon (_ibidem_, p. 177; R., p. 230): he nevertheless makes an assumption of freedom (although only _idealiter_, and as a postulate) by his celebrated conclusion: "You can, because you ought"; and this on the strength of his precious ethical basis, which, as we see, floats in the air incorporeal. But if it has once been clearly recognised that a thing =is not=, and =cannot be=, what is the use of all the postulates in the world? It would be much more to the purpose to cast away that on which the postulate is based, because it is an impossible supposition; and this course would be justified by the rule _a non posse ad non esse valet consequentia_;[12] and by a _reductio ad absurdum_, which would at the same time be fatal to the Categorical Imperative. Instead of which one false doctrine is built up on the other.