 Purported explanations can be informally divided into two broad categories—those involving agents, agency, intention, and the like; and those involving mechanism, physical causality, natural processes, and the like. The distinction is not, of course, a clean one (functioning artifacts typically involve both), but is useful enough in a rough and ready way, and in what follows agent explanations and mechanical explanations respectively will be used as convenient handles. Nothing pernicious is built into either the broad distinction or the specified terminology.