On the other hand the question, how the imperative of morality is possible, is undoubtedly one, the only one? demanding a solution, as this is not at all hypothetical, and the objective necessity which it presents cannot rest on any hypothesis, as is the case with the hypothetical imperatives.  Only here we must never leave out of consideration that we cannot make out by any example, in other words empirically, whether there is such an imperative at all; but it is rather to be feared that all those which seem to be categorical may yet be at bottom hypothetical.  For instance, when the precept is:  Thou shalt not promise deceitfully; and it is assumed that the necessity of this is not a mere counsel to avoid some other evil, so that it should mean:  thou shalt not make a lying promise, lest if it become known thou shouldst destroy thy credit, but that an action of this kind must be regarded as evil in itself, so that the imperative of the prohibition is categorical; then we cannot show with certainty in any example that the will was determined merely by the law, without any other spring of action, although it may appear to be so.  For it is always possible that fear of disgrace, perhaps also obscure dread of other dangers, may have a secret influence on the will.  Who can prove by experience the non-existence of a cause when all that experience tells us is that we do not perceive it?  But in such a case the so-called moral imperative, which as such appears to be categorical and unconditional, would in reality be only a pragmatic precept, drawing our attention to our own interests, and merely teaching us to take these into consideration.

We shall therefore have to investigate a priori the possibility of a categorical imperative, as we have not in this case the advantage of its reality being given in experience, so that [the elucidation of] its possibility should be requisite only for its explanation, not for its establishment.  In the mean-time it may be discerned beforehand that the categorical imperative alone has the purport of a practical law:  all the rest may indeed be called principles of the will but not laws, since whatever is only necessary for the attainment of some arbitrary purpose may be considered as in itself contingent, and we can at any time be free from the precept if we give up the purpose:  on the contrary, the unconditional command leaves the will no liberty to choose the opposite; consequently it alone carries with it that necessity which we require in a law.

Secondly, in the case of this categorical imperative or law of morality, the difficulty (of discerning its possibility) is a very profound one.  It is an a priori synthetical practical proposition; [Footnote:  I connect the act with the will without presupposing any condition resulting from any inclination, but d priori, and therefore necessarily (though only objectively, i. e. assuming the idea of a reason possessing full power over all subjective motives).  This is accordingly