Abstract
This article examines the free will problem as it arises within Thomas Hobbes' naturalistic science of morals in early modern Europe. It explains that during this period, the problem of moral and legal responsibility became acute as mechanical philosophy was extended to human psychology and as a result human choices were explained in terms of desires and preferences rather than being represented as acts of an autonomous faculty. It describes how Hobbes changed the face of moral philosophy, through his Leviathan, in ways that still structure and resonate within the contemporary debate.