The term "self" is used to refer to a person as that person conceives and knows itself. Locke's definition asserts a close connection between the nature of selves, or persons, and the access they have to themselves and their identities. The contents of self-consciousness, which includes both introspective awareness of one's current psychological states and memory awareness of one's past, are neutral with respect to the metaphysical nature of the self. There are memory demonstratives that enable one to refer to specific things remembered in the past; and these things can include persons, and these persons can include oneself. This chapter addresses the question of what gives memories their first-person content. It uses the example of the Parfit people rather than a more realistic, and more often discussed, case of fission, namely that in which it involves transplanting the two hemispheres of someone's brain into two different bodies.

This chapter claims that the cumulative force of various empirical data and conceptual considerations makes it more reasonable to accept than to deny that many animals are self-aware. It considers studies focusing on animals' preferences. In the philosophy of mind, desires and beliefs are classified as propositional attitudes, mental states that take propositions or sentences as their objects. Desires to do certain things and intentional actions that involve doing them suggest at least some rudimentary awareness of oneself as persisting through time. Strengthening the case for intentional action, and therefore for bodily self-awareness, is evidence of more sophisticated behaviors in animals involving planning, complex problem-solving, and/or tool use. Like intentional action involving a plan, fear requires some awareness that one will continue into the future. Since Gordon Gallup's pioneering experiments, self-recognition with mirrors has often been cited as evidence of self-awareness in animals.