《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2节
On the hypothesis, then, of freedom of the will, morality together with its principle follows from it by mere analysis of the conception. However, the latter is a synthetic proposition; viz., an absolutely good will is that whose maxim can always include itself regarded as a universal law; for this property of its maxim can never be discovered by analysing the conception of an absolutely good will. Now such synthetic propositions are only possible in this way: that the two cognitions are connected together by their union with a third in which they are both to be found. The positive concept of freedom furnishes this third cognition, which cannot, as with physical causes, be the nature of the sensible world (in the concept of which we find conjoined the concept of something in relation as cause to something else as effect). We cannot now at once show what this third is to which freedom points us and of which we have an idea a priori, nor can we make intelligible how the concept of freedom is shown to be legitimate from principles of pure practical reason and with it the possibility of a categorical imperative; but some further preparation is required. Freedom must be presupposed as a Property of the Will of all Rational Beings
注释摘要
这段论述处在全书论证的一个枢纽位置：康德刚刚从自由的理念推导出道德原则，现在却反过来指出，这个推导内部隐藏着一个更深的困难。表面上看，一旦我们预设意志是自由的，那么道德连同其原则似乎就可以通过单纯分析自由的概念得出来。但康德立刻纠正了这个印象，他指出“后者”，也就是“一个绝对善的意志就是那种其准则总能够将自身视为普遍法则的意志”这个命题，实际上是一个综合命…