People engage in pure moral inquiry whenever they inquire into the moral features of some act, agent, or state of affairs without inquiring into the non-moral features of that act, agent, or state of affairs. The first section of this chapter argues that ordinary people act rationally when they engage in pure moral inquiry, and so any adequate view in metaethics ought to be able to explain this fact. The Puzzle of Pure Moral Motivation is to provide such an explanation. The remaining sections of the chapter argue that each of the standard views in metaethics has trouble providing such an explanation. A metaethical view can provide such an explanation only if it meets two constraints: it allows ordinary moral inquirers to know the essences of moral properties, and the essence of each moral property makes it rational to care for its own sake whether that property is instantiated.
