The Critique of Practical Reason [36]
to the experience of physical nature; hence, it seems absurd to expect to find in the world of sense a case which, while as such it depends only on the law of nature, yet admits of the application to it of a law of freedom, and to which we can apply the supersensible idea of the morally good which is to be exhibited in it in concreto. Thus, the judgement of the pure practical reason is subject to the same difficulties as that of the pure theoretical reason. The latter, however, had means at hand of escaping from these difficulties, because, in regard to the theoretical employment, intuitions were required to which pure concepts of the understanding could be applied, and such intuitions (though only of objects of the senses) can be given a priori and, therefore, as far as regards the union of the manifold in them, conforming to the pure a priori concepts of the understanding as schemata. On the other hand, the morally good is something whose object is supersensible; for which, therefore, nothing corresponding can be found in any sensible intuition. Judgement depending on laws of pure practical reason seems, therefore, to be subject to special difficulties arising from this, that a law of freedom is to be applied to actions, which are events taking place in the world of sense, and which, so far, belong to physical nature. But here again is opened a favourable prospect for the pure practical judgement. When I subsume under a pure practical law an action possible to me in the world of sense, I am not concerned with the possibility of the action as an event in the world of sense. This is a matter that belongs to the decision of reason in its theoretic use according to the law of causality, which is a pure concept of the understanding, for which reason has a schema in the sensible intuition. Physical causality, or the condition under which it takes place, belongs to the physical concepts, the schema of which is sketched by transcendental imagination. Here, however, we have to do, not with the schema of a case that occurs according to laws, but with the schema of a law itself (if the word is allowable here), since the fact that the will (not the action relatively to its effect) is determined by the law alone without any other principle, connects the notion of causality with quite different conditions from those which constitute physical connection. The physical law being a law to which the objects of sensible intuition, as such, are subject, must have a schema corresponding to it- that is, a general procedure of the imagination (by which it exhibits a priori to the senses the pure concept of the understanding which the law determines). But the law of freedom (that is, of a causality not subject to sensible conditions), and consequently the concept of the unconditionally good, cannot have any intuition, nor consequently any schema supplied to it for the purpose of its application in concreto. Consequently the moral law has no faculty but the understanding to aid its application to physical objects (not the imagination); and the understanding for the purposes of the judgement can provide for an idea of the reason, not a schema of the sensibility, but a law, though only as to its form as law; such a law, however, as can be exhibited in concreto in objects of the senses, and therefore a law of nature. We can therefore call this law the type of the moral law. The rule of the judgement according to laws of pure practical reason is this: ask yourself whether, if the action you propose were to take place by a law of the system of nature of which you were yourself a part, you could regard it as possible by your own will. Everyone does, in fact, decide by this rule whether actions are morally good or evil. Thus, people say: "If everyone permitted himself to deceive, when he thought it to his advantage; or thought himself justified in shortening his life as soon as he was thoroughly weary of it; or looked with perfect indifference on the necessity of others; and if you belonged to such an order of things, would you do so with the assent