Personal identity
Personal identity concerns the conditions under which a person at one time is the same individual as a person at another time.
Numerical identity: The relation in which an entity is one and the same entity as itself across descriptions or times. Personal identity asks whether a person at different times is numerically one and the same.
Animalism: The view that each of us is fundamentally an animal, specifically a human organism. It makes biological continuity, rather than mental continuity, decisive.
John Locke: An English philosopher whose writings helped establish empiricism and political liberalism. Locke connected personal identity to consciousness and memory in a highly influential account.
Personal identity and moral responsibility: The inquiry into how persistence conditions relate to praise, blame, and accountability over time. Responsibility may depend on whether a later person is identical to the earlier agent.
Psychological continuity: A relation linking mental states across time through overlapping memories, intentions, beliefs, and character traits. Many accounts identify a person over time through connected mental life.
Psychological criterion of personal identity: The view that a person persists through time when the right psychological connections link their mental states. It directly competes with organism-based accounts of what makes someone persist.
Derek Parfit: A British philosopher known for work on personal identity, rationality, and ethics. Parfit argued that psychological continuity can matter even when strict identity does not.
Survival (personal identity): The question of what it means for someone to continue or survive beyond a particular time or event. Parfit’s work distinguishes survival-like relations from strict numerical identity.
Bodily continuity: The persistence of one living human body through change in its parts and appearance. A bodily account treats the continuing organism as the person’s identity anchor.
Ship of Theseus: A puzzle about whether an object remains the same after all its parts are gradually replaced. It frames the broader question of how identity survives material change.