《道德形而上学基础·第一节·从普通的道德理性知识过渡到哲学的道德理性知识》第3节
In the physical constitution of an organized being, that is, a being adapted suitably to the purposes of life, we assume it as a fundamental principle that no organ for any purpose will be found but what is also the fittest and best adapted for that purpose. Now in a being which has reason and a will, if the proper object of nature were its conservation, its welfare, in a word, its happiness, then nature would have hit upon a very bad arrangement in selecting the reason of the creature to carry out this purpose. For all the actions which the creature has to perform with a view to this purpose, and the whole rule of its conduct, would be far more surely prescribed to it by instinct, and that end would have been attained thereby much more certainly than it ever can be by reason. Should reason have been communicated to this favoured creature over and above, it must only have served it to contemplate the happy constitution of its nature, to admire it, to congratulate itself thereon, and to feel thankful for it to the beneficent cause, but not that it should subject its desires to that weak and delusive guidance and meddle bunglingly with the purpose of nature. In a word, nature would have taken care that reason should not break forth into practical exercise, nor have the presumption, with its weak insight, to think out for itself the plan of happiness, and of the means of attaining it. Nature would not only have taken on herself the choice of the ends, but also of the means, and with wise foresight would have entrusted both to instinct.
注释摘要
这段论证在全书的结构里扮演一个很特别的角色。此前的篇幅中，康德已经提出：世界上唯一无限制地称得上好的，就是一个善良意志；这个善不以它所产生的效果来衡量，甚至哪怕它完全无力实现任何目的，也像一颗宝石那样凭自身闪耀。这样一个观念乍看起来极高远，高远得令人起疑——普通人也许会点头认可，但转念一想，又难免觉得这不过是头脑发热的空想，难道我们误解了自然把理性交给人类…