Long claimed to be the dominant conception of practical reason, the Humean theory that reasons for action are instrumental, or explained by desires, is the basis for a range of worries about the objective prescriptivity of morality. As a result, it has come under intense attack in recent decades. A wide variety of arguments have been advanced which purport to show that it is false, or surprisingly, even that it is incoherent. Slaves of the Passions aims toset the record straight, by advancing a version of the Humean theory of reasons which withstands this sophisticated array of objections. Mark Schroeder defends a radical new view which, if correct, means that the commitments of the Humean theory have been widely misunderstood. Along the way, he raises and addresses questions about the fundamental structure of reasons, the nature of normative explanations, the aims of and challenges facing reductive views in metaethics, the weight of reasons, the nature of desire, moral epistemology, and most importantly, the relationship between agent-relational and agent-neutral reasons foraction.