Can Psychology Be a Unified Science?

Jaegwon Kim has argued that if psychological kinds are multiply realizable then no single psychological theory can describe regularities ranging over psychological states. Instead, psychology must be fractured, with human psychology covering states realized in the human way, martian psychology covering states realized in the martian way, and so on. I show that even if one accepts the principles that motivate Kim’s argument, his conclusion does not follow. I then offer a dilemma that forces Kim to concede the possibility of a unified psychology. I close with a discussion of what, according to Jerry Fodor, is “really bugging” Kim.