Adorno's moral philosophy is famously problematic. One of the main reasons for this is that it revolves around the moral addendum: a physical impulse of solidarity with suffering beings that, he argues, cannot and should not be rationalized. I show that, since this moral addendum remains vague and since Adorno's radical negativity forces him to dismiss as uncritical all other approaches to morality, he deliberately places his thought in danger of relapsing into irrationality. Most commentators therefore disagree about the manner in which Adorno's references to the moral addendum can be translated into a moral theory. In this paper, I bring in some often overlooked material to form a more complete overview of the issues at hand and to adjudicate this contested area. I do this by briefly discussing Schopenhauer's moral observations on Mitleid and by focusing on Adorno's references to animal cruelty and corporeality. Although this interpretation stays close to Adorno's observations on the moral addendum, it forces us to accept that his moral philosophy is rather weak. I conclude, however, that this weakness reflects a disturbing aspect of reality and in that sense has critical value.