Identity (philosophy)

{{{}}}In philosophy, identity, from Latin: identitas ("sameness"), is the relation each thing bears just to itself. The notion of identity gives rise to many philosophical problems, including the identity of indiscernibles (if x and y share all their properties, are they one and the same thing?), and questions about change and personal identity over time (what has to be the case for a person x at one time and a person y at a later time to be one and the same person?).

It is important to distinguish the philosophical concept of identity from the more well-known notion of identity in use in psychology and the social sciences. The philosophical concept concerns a relation, specifically, a relation that x and y stand in just in case they are one and the same thing, or identical to each other (i.e. just in case x = y). The sociological notion of identity, by contrast, has to do with a person's self-conception, social presentation, and more generally, the aspects of a person that make them unique, or qualitatively different from others (e.g. cultural identity, gender identity, national Identity, online identity and processes of identity formation.)

Metaphysics of identity

Metaphysicians, and sometimes philosophers of language and mind, ask other questions:

• What does it mean for an object to be the same as itself?
• If x and y are identical (are the same thing), must they always be identical? Are they necessarily identical?
• What does it mean for an object to be the same, if it changes over time? (Is apple_t the same as apple_t+1?)
• If an object's parts are entirely replaced over time, as in the Ship of Theseus example, in what way is it the same?

The Law of identity originates from classical antiquity. The modern formulation of identity is that of , who held that x is the same as y if and only if every predicate true of x is true of y as well.

Leibniz's ideas have taken root in the ,where they have influenced the development of the predicate calculus as Leibniz's law. Mathematicians sometimes distinguish identity from equality. More mundanely, an identity in mathematics may be an equation that holds true for all values of a variable. Hegel argued that things are inherently self-contradictory and that the notion of something being self-identical only made sense if it were not also not-identical or different from itself and did not also imply the latter. In Hegel's words, "Identity is the identity of identity and non-identity." More recent metaphysicians have discussed trans-world identity—the notion that there can be the same object in different possible worlds. An alternative to trans-world identity is the counterpart relation in Counterpart theory. It is a similarity relation that rejects trans-world individuals and instead defends an objects counterpart - the most similar object.

See also

• Nominal identity
• Cultural identity
• Digital identity
• Ethnic identity
• Social identity
• Online identity
• Identity theft
• Counterpart theory
• Identity (social science)

References

• Gallois, A. 1998: Occasions of identity. Oxford: Oxford University Press. ISBN 0-19-823744-8 Google books
• Parfit, D. 1984: Reasons and persons. Oxford: Oxford University Press. ISBN 0-19-824908-X Google books
• Robinson, D. 1985: Can amoebae divide without multiplying? Australasian journal of philosophy, 63(3): 299–319. doi:10.1080/00048408512341901
• Sidelle, A. 2000: [Review of Gallois (1998)]. Philosophical review, 109(3): 469-471. JSTOR
• Sider, T. 2001: [Review of Gallois (1998)]. British journal for the philosophy science, 52(2): 401-405. doi:10.1093/bjps/52.2.401

External references

General Information

• Stanford Encyclopedia of Philosophy: Identity, First published Wed Dec 15, 2004; substantive revision Sun Oct 1, 2006.
• Stanford Encyclopedia of Philosophy: Identity over time. First published Fri 18 March 2005.
• Stanford Encyclopedia of Philosophy: Personal identity. First published Tue Aug 20, 2002; substantive revision Tue Feb 20, 2007.
• Stanford Encyclopedia of Philosophy: Relative identity. First published Mon 22 April 2002.

Citations