Kant’s theory of friendship is crucial in defending his ethics against the longstanding charge of emotional detachment. But his theory of friendship is vulnerable to this charge too: the Kantian sage can appear to reject sympathetic suffering when she cannot help a suffering friend. I argue that Kant is committed to the view that both sages and ordinary people must suffer in sympathy with friends even when they cannot help, because sympathy is necessary to fulfill the imperfect duty to adopt others’ merely permissible ends (MPEs), and we ought to take friends’ MPEs as our own. MPEs are individuated in terms of concepts which include marks of the first person, and no marks of law other than permissibility. To adopt ends of others individuated in terms of such concepts rather than merely promote them as means to different ends, those concepts must engage with one’s feelings in a way that requires sympathy.

This paper argues that Kant endorses a distinction between rational and natural sympathy, and it presents an interpretation of rational sympathy as a power of voluntary a posteriori productive imagination. In rational sympathy we draw on the imagination’s voluntary powers (a) to subjectively unify the contents of intuition, in order to imaginatively put ourselves in others’ places, and (b) to associate imagined intuitional contents with the concepts others use to convey their feelings, in such a way that those contents prompt feelings in us that are like their feelings.

In Kant’s Defense of Common Moral Experience: A Phenomenological Account, Jeanine Grenberg argues for the centrality to Kant’s ethics of the experience of the feeling of moral constraint, especially as that feeling is described in Kant’s fact of reason argument. She criticizes interpretations of the fact of reason that interpret it as primarily a certain kind of act. I defend my version of an act-based interpretation against Grenberg’s criticisms, flesh out the Fichtean background of that interpretation and raise some further questions about Grenberg’s account.