Where does identity collide?

An attribute or set of attributes that uniquely describes a subject within a given context. NIST SP 800-63-3 fixed that definition in 2017 and split the lifecycle into identity proofing, which establishes that a real person exists and is the applicant, authentication, which binds a returning claimant to the proofed record, and federation, which carries the assertion between systems. Cameron's 2005 Laws of Identity argued from failed universal schemes that a workable system must give users control, disclose minimally, and support many operators. Anderson, Durbin, and Salinger's 2008 survey of identity theft showed the construct's failure mode: the attributes are copied and the record is bound to the wrong person. What distinguishes this meaning is that identity is a record, contextual and revocable, and there can be as many as there are systems.[1][2][3]

Unit

A subject's record in one system or federation

Recovery means

Re-proofing and re-binding after compromise; account recovery

Measured by

Identity assurance level; proofing evidence strength; fraud and account-takeover rates

A person's settled sense of who they are, arrived at by working through alternatives and committing to some of them. Erikson made identity versus role confusion the crisis of adolescence in 1968 and gave the field the word moratorium for the period of search. Marcia operationalised it in 1966 as four statuses crossed from two dimensions: achievement after exploration and commitment, foreclosure with commitment but no exploration, moratorium in exploration without commitment, and diffusion with neither. Crocetti, Rubini, and Meeus's 2008 three-factor model split the process into commitment, in-depth exploration, and reconsideration, and gave it a short questionnaire. What distinguishes this meaning is that identity is a developmental outcome with a process behind it, and the process, not the content, is what the field measures.[4][5][6]

Unit

An adolescent or young adult, across domains such as education and relationships

Recovery means

Not applicable, the criterion is movement from diffusion or moratorium toward achievement

Measured by

Identity-status interview; U-MICS commitment, exploration, and reconsideration scores

The part of a person's self-concept that derives from knowledge of membership in a social group together with the value and emotional significance attached to that membership. Tajfel and Turner fixed the theory in 1979 to explain why minimal, arbitrary groups produced in-group favouritism: people seek positive distinctiveness for the groups they belong to, and discrimination follows from the comparison. Turner, Hogg, Oakes, Reicher, and Wetherell's 1987 self-categorization theory explained the mechanism: the self can be categorised at the personal or the group level, and when the group level is salient the person perceives themselves as interchangeable with other members. What distinguishes this meaning is that identity is plural and situational (a person has as many social identities as salient groups) and it explains group behaviour, not individual development.[7][8]

Unit

A person in a situation where a group membership is salient

Recovery means

Not applicable, the criterion is which categorisation is salient and what behaviour follows

Measured by

In-group identification scales; minimal-group allocation; depersonalisation and self-stereotyping measures

Members' shared answer to the question of what the organisation is. Albert and Whetten fixed the three criteria in 1985 (the features members regard as central, distinctive from comparable organisations, and enduring over time) and added that organisations may hold dual identities, such as a university that is both a church and a business. Gioia, Schultz, and Corley argued in 2000 that the enduring criterion is wrong: identity is adaptively unstable, because its labels persist while their meanings shift in response to how outsiders see the organisation, its image. What distinguishes this meaning is that identity belongs to a collective, is held as a set of shared claims, and is studied through what the organisation says about itself and does under threat.[9][10]

Unit

An organisation, as construed by its members over time

Recovery means

Not applicable, the criterion is continuity of identity claims through change, or a managed identity change

Measured by

Interview and document coding of identity claims; member consensus on central and distinctive attributes

The relation between a person now and a person at another time in virtue of which they are one and the same. Locke fixed the modern problem in 1690 by separating the person from both the soul and the body and locating identity in continuity of consciousness, so that a prince's memories in a cobbler's body make the cobbler the prince. Parfit argued in 1984 that the relation admits of degrees and can branch, that identity is therefore not what matters in survival, and that psychological continuity and connectedness carry the weight instead. Olson answered in 1997 that we are human animals, and that our persistence conditions are biological rather than psychological. What distinguishes this meaning is that identity is numerical sameness across time, a metaphysical relation tested by thought experiments, and it has nothing to do with what a person feels themselves to be.[11][12][13]

Unit

A person at two times, or one person and a candidate successor

Recovery means

Not applicable, the criterion is whether the later person is the earlier one

Measured by

Not measured; argued through cases of fission, teletransportation, and amnesia

An element of a set with a binary operation such that combining it with any element returns that element unchanged. Group theory requires exactly one, written e or 1, and Dummit and Foote's textbook proves its uniqueness in the first pages: if e and f are both identities then e = ef = f. The identity function on a set sends each element to itself and is the identity element of the group of bijections under composition; the identity matrix, with ones on the diagonal, is the identity for matrix multiplication and represents the identity map in any basis. An identity in the other meaning, such as sin²x + cos²x = 1, is an equation true for all values of its variables. What distinguishes this meaning is that identity is a neutral element defined by what it does not do, and it exists or not as a theorem, never as a matter of degree.[14]

Unit

A set with an operation, or a linear space with a basis

Recovery means

Not applicable, an identity element is unique and does not change

Measured by

Not measured; proved from the axioms