Although I shall largely use “action,” “behavior,” “decision,” and “choice” as synonymous terms, it is sometimes useful to distinguish among them. The broadest category is behavior, understood as any bodily movement whose origin is internal to the agent, not external (as when he is carried away by a landslide). Action is intentional behavior, caused by the desires and beliefs of the agent. Thus reflex behaviors are not actions; having an erection is not an action (but it may be induced by one, such as taking Viagra); falling asleep is not an action (but may be induced by taking a sleeping pill). An action may or may not be preceded by a conscious decision. When I drive to work along my usual route I do not consciously decide to turn right here and left there, although each action is intentional or goal-oriented. The very first time or times I drove to work, however, the actions were preceded by explicit decisions. In fact, they were preceded by an explicit choice among alternative paths. Although all choices are decisions, the converse is not true. When I decide to pick up the book I have been reading, I need not have any explicit alternative in mind. I see the book on the table; the sight reminds me that I have enjoyed reading it; and I decide to pick it up. No choice is involved.