I want to reopen the question whether the same bit of behavior, say an action we perform such as climbing a ladder, can be given both a “mechanistic” explanation, in terms of physiological processes and laws, and a “purposive” explanation, in terms of “reasons” (e.g., goals and beliefs). In a paper published in 1968, Norman Malcolm defended a negative answer. He argued that once an action has been explained by setting forth its physiological causal antecedents it is no longer open to us to explain it by citing the agent's reasons, that is, his beliefs, desires, intentions, and the like. Alvin Goldman immediately replied to Malcolm, arguing that mechanistic and purposive explanations are indeed compatible, that we can in fact characterize a type of situation in which one and the same behavior can be seen to be explainable both physiologically and rationally.

I want to reopen this debate not only because there is more to be said on this issue but also, and more importantly, because the issue has significant implications for some problems of much current interest in the philosophy of mind. A proper appreciation of the broader methodological issues and options involved will, I believe, help us to get clearer about some matters of current controversy. As we shall see, the question of explanatory compatibility leads us to more general questions about the pos-sibility of multiple explanations of a single explanandum, and the relationship between two distinct explanatory theories covering overlapping domains of phenomena.