Who are the agents?

The question who (or which things) are the agents has attracted a very wide range of different answers. For some, only humans can satisfy the necessary conditions for agency; others extend the concept to a wide range of animals or even plants; and some believe there are also agents outside the biological realm. Do these different answers constitute substantively different views about the same question? Or are the disagreements really terminological ones, at root, owed to different ‘definitions’ of agency? In this paper, I try to provide examples both of disputes which do, and disputes which do not seem amenable to this sort of terminological deflation. I then try to diagnose the difference, by offering a view about how we must think about the concept of agency if it is to play a role in genuinely substantive disagreement, combining Susan Carey’s idea that agency is a ‘core concept’ with an externalist account of how the concept must work, if it is to figure in thoroughly substantive disputes about who the agents are.