Abstract
Biological agency has received much attention in recent philosophy of biology. But what is the motivation for introducing talk of agency into biology and what is meant by “agent”? Two distinct motivations can be discerned. The first is that thinking of organisms as agents helps to articulate what is distinctive about organisms vis-à-vis other biological entities. The second is that treating organisms as agent-like is a useful heuristic for understanding their evolved behavior. The concept of agent itself may be understood in at least four different ways: minimal agent, intelligent agent, rational agent, and intentional agent. Which understanding is most appropriate depends on which of the two motivations we are concerned with.