In § 116 of Achenwall/Pütter Elementa Iuris Naturae the following possibilities of conflicts of duties are listed: “There can be a conflict 1. of prohibiting laws with each other, 2. of prescribing laws with each other, 3. of prescribing laws with prohibiting laws.” It will be examined in this article, whether the three theses can be made plausible by examples, and especially, whether thesis No. 1 is convincing in relation to the idea that perfect duties (or prohibiting laws) cannot come into conflict with each other. Furthermore the thesis of Immanuel Kant in his Metaphysics of Morals will be discussed, that there is no conflict of duties at all, but only a “contradiction of reasons of bindingness”. Finally, the argument of Achenwall/Pütter, that the well known duty “bring yourself to perfection!” (Latin: “perfice te!”) may come into conflict with duties in respect to others, and that an argument for a right to act against others in cases of necessity can be given in this context (cf. Achenwall/Pütter, §§ 118, 205, 296).
Kant’s Categorical Imperative and Duty