AbstractIn this paper, I present three claims belonging to Cavendish's theory of the passions. First, positive and negative passions are species of love and hate. Second, love and hate involve pleasure and pain. Third, pleasure and pain are regular and irregular, where these notions are to be understood in teleological terms. From these commitments, it follows that hate is irregular. I argue that this consequence is a problematic one for Cavendish. After defending my reading through a consideration of Cavendish's reflections on mental health and disorder, I explore ways in which she might revise her commitments to avoid the problem. Throughout the paper, I demonstrate the extent to which Cavendish's theory of the passions draws on Aristotelian and Augustinian ideas that loomed large in late sixteenth‐ and early seventeenth‐century writings on the topic.