Property

A way something can exist; a quality or characteristic that allows it to resemble, be used like, or be treated like other things with that same property.

Accidental Property

A property that can change without changing what the thing fundamentally is. Example: An apple’s color or size.

Essential Property

A property that cannot change without changing what the thing fundamentally is. Example: “Being a dog” for a dog.

Essentialism

The belief that things have essential properties that define what they truly are.

Non-Essentialism (Constructivism)

The belief that things do not have fixed essences; categories and identities are socially or conceptually constructed.

Ship of Theseus Dilemma

A thought experiment about identity and change — if all parts of something are replaced, is it still the same thing?

Definition Problem

The more specific a definition is, the fewer things it applies to; the more general it is, the less meaningful it becomes.

Locke’s Problem of the Resurrection

Questioning how a person could be the same at resurrection if their body has completely decomposed — which properties make them the same person?

Soul (Locke’s View)

The essential property of a person — not a physical object, but their continuing identity or way of being.

The Prince and the Cobbler

Locke’s thought experiment — if a prince’s soul and memories enter a cobbler’s body, it is the same self (same memories), but not the same man (different body).

Psychological Continuity Theory

The idea that personal identity depends on an unbroken stream of consciousness and memory over time.

Memory (Locke)

The core of personal identity — only you can have your memories from your point of view.

Derek Parfit’s View

There is no single, continuous self; identity is an illusion created by overlapping experiences and memories.

Psychological Connectedness

The relationship between different “versions” of yourself across time — each moment of consciousness is new but related through shared memories and traits.

Consciousness (Parfit’s Analogy)

Like a computer’s operating system — every time it restarts, it’s a new instance, not the same one continuing.