Thick concepts and reasons for action

This thesis aims to clarify the claim that thick concepts provide reasons for action, and explore whether any version of that claim can be defended. The claim is notably connected with the philosopher Bernard Williams, but here I do not approach it as a defence of Williams or his views. I understand reasons for action to be facts that stand in a reason relation to agents and actions. Reasons for action can be normative reasons for an agent to act or reasons why she acts. In order to defend any version of the claim that thick concepts are distinctive in providing reasons for action, it is necessary to take a position on thick concepts and defend them as evaluative concepts. My conclusion is that some understandings of the claim can be defended, albeit in a restricted range of applications.