《道德形而上学基础·第三节·从道德形而上学过渡到纯粹实践理性批判》第19节
Concluding Remark The speculative employment of reason with respect to nature leads to the absolute necessity of some supreme cause of the world: the practical employment of reason with a view to freedom leads also to absolute necessity, but only of the laws of the actions of a rational being as such. Now it is an essential principle of reason, however employed, to push its knowledge to a consciousness of its necessity (without which it would not be rational knowledge). It is, however, an equally essential restriction of the same reason that it can neither discern the necessity of what is or what happens, nor of what ought to happen, unless a condition is supposed on which it is or happens or ought to happen. In this way, however, by the constant inquiry for the condition, the satisfaction of reason is only further and further postponed. Hence it unceasingly seeks the unconditionally necessary and finds itself forced to assume it, although without any means of making it comprehensible to itself, happy enough if only it can discover a conception which agrees with this assumption. It is therefore no fault in our deduction of the supreme principle of morality, but an objection that should be made to human reason in general, that it cannot enable us to conceive the absolute necessity of an unconditional practical law (such as the categorical imperative must be). It cannot be blamed for refusing to explain this necessity by a condition, that is to say, by means of some interest assumed as a basis, since the law would then cease to be a supreme law of reason. And thus while we do not comprehend the practical unconditional necessity of the moral imperative, we yet comprehend its incomprehensibility, and this is all that can be fairly demanded of a philosophy which strives to carry its principles up to the very limit of human reason.
注释摘要
这部著作的整个论证，到这段结语，其实是在做一件边界勘定的事。康德在全书开头提出要寻找并确立道德的最高原则，现在他走到了终点，但他并没有说“我们找到了”。他说的是：我们已经走到人类理性能够走到的最远处，再往前不是知识，而是深渊。 他在这里做了一个对称的比较。理性的思辨运用，也就是我们用来认识自然的那部分理性，它一路追问因果链条，最后必然要假定一个世界的最高的…