Difference (poststructuralism)

Difference is a key concept of philosophy, denoting the process or set of properties by which one entity is distinguished from another within a relational field or a given conceptual system. In the Western philosophical system, difference is traditionally viewed as being opposed to identity, following the Principles of Leibniz, and in particular, his Law of the identity of indiscernibles. In structuralist and poststructuralist accounts, however, difference is understood to be constitutive of both meaning and identity. In other words, because identity (particularly, personal identity) is viewed in non-essentialist terms as a construct, and because constructs only produce meaning through the interplay of differences (see below), it is the case that for both structuralism and poststructuralism, identity cannot be said to exist without difference.

Gottfried Leibniz's Principle of the identity of indiscernibles states that two things are identical if and only if they share the same and only the same properties. This is a principle which defines identity rather than difference, although it established the tradition in logic and analytical philosophy of conceiving of identity and difference as oppositional.

In his Critique of Pure Reason, Immanuel Kant argues that it is necessary to distinguish between the thing in itself and its appearance. Even if two objects have completely the same properties, if they are at two different places at the same time, they are numerically different:

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