This chapter examines David Lewis's view that we are temporal parts of animals. It examines three arguments for the view that persisting things have temporal parts–four-dimensionalism. One is that it solves the problem of temporary intrinsics. The second is that it solves metaphysical problems about the persistence of material objects without the mystery of constitutionalism–though these solutions require a counterpart-theoretic account of modality. The third is that it solves problems of personal identity–involving fission, for instance–in an attractive way. It is then argued that according to four-dimensionalism, the bearers of such properties as thinking and acting are momentary stages, forcing us to choose between saying that we don't strictly think and saying that we don't persist.
Keywords: David Lewis, fission, four-dimensionalism, modality, persistence, personal identity, temporal part, temporary intrinsic