How can reasons explain actions? What is the force of "because" in "He did this because..." followed by a statement of the agent's intentions? The answer involves some concept of what can count as explanation, and the history of science indicates that the acceptability of explanations depends, in part, on a scientific community which has decided to pursue its inquiries in one direction rather than another. The first part of this paper examines this pragmatic aspect of explanations; the second part (...) draws on this examination in the hope of elucidating the way reasons explain actions. The possibility of eliminating our ordinary, "purposive," explanations of actions in favor of some "mechanistic," neuro-physiological, account is then considered. (shrink)