Ordinary English usage for the terms 'identity', 'identical', etc.

C. M. Sperberg-McQueen, October 2014


Documentation of ordinary English usage

The definitions given for the usage I propose we should follow are adapted from the following definitions, drawn from the dictionaries listed below. Note that this is not an exhaustive list of every definition offered by the dictionaries in question.

identity
  • the condition of being oneself or itself, and not another ... (ACD, def 2)
  • state or fact of being the same one (ACD, def 4)
  • the condition or fact of being some specific person or thing ... (NWD, def 2a)
  • Your identity is ... who you are. E.g. I had guess the identity of her lover... The clues he left did not establish his identity... Glen whipped off the mask to reveal his identity. (Cobuild, def 1.1)
  • condition or character as to who a person or what a thing is: a case of mistaken identity (ACD, def 3)
  • the condition or fact of being some specific person or thing; individuality (NWD, def 2a)
  • the condition of being the same as something or someone assumed, described, or claimed (NWD, def 2b)
  • the condition of being the same with something described or asserted (W7, def 3)
  • The sameness of a person or thing at all times or in all circumstances; the condition or fact that a person or thing is itself and not something else; ... (OED, def 2)
  • state or fact of remaining the same one, as under varying aspects or conditions (ACD, def 1)
  • the condition or fact of being the same in all qualities under consideration; sameness; oneness (NWD, def 1)
  • unity and persistence of personality (W7, def 2)
  • The quality or condition of being the same in substance, composition, nature, properties, or in particular qualities under consideration; absolute or essential sameness; oneness. (OED, def 1)
  • sameness in all that constitutes the objective reality of a thing : ONENESS (W7, def 1b)

Omitted here are definitions that delineate the broader sense of identity as strong similarity (e.g. "exact likeness in nature or qualities"). It is not proposed that we use the word in that sense.

The OED discusses the relation to other terms in a note:

Various suggestions have been offered as to the formation. Need was evidently felt for a noun of condition or quality from idem to express the notion of 'sameness', side by side with those of 'likeness' and 'oneness' expressed by similitās and ūnitās: hence the form of the suffix. ...

Note the occurrence in several definitions of the idea of identity as involving sameness over time or sameness under different circumstances; this connects with the use of the term identity to discuss the effects of mutation or other side effects in programming languages which have mutation and other side effects. But note also that these definitions do not restrict the concept of identity to things which themselves undergo mutation. They apply both to mutable and to immutable objects which persist over time or which can be considered in different circumstances.

identify
  • to establish the identity of (W7, def 2a)
  • To determine (something) to be the same with something conceived, known, asserted, etc.; to determine or establish the identity of; to ascertain or establish what a given thing or who a given person is; in Nat. Hist. to refer a specimen to its proper species. (OED, def 2)
  • to recognize or establish as being a particular person or thing; attest or prove to be as purported or asserted: to identify handwriting, identify the bearer of a check (ACD, def 1)
  • to show to be a certain person or thing; fix the identity of; show to be the same as something or someone assumed, described, or claimed. (NWD, def 2)
  • If you can identify someone or something, you are able to recognize them ... because they have a particular quality. eg An individual bird can identify the call of its own species... a device which identifies its owner through his fingerprint pattern. (Cobuild, def 1.1).
  • [If you can identify someone or something,] 1.2 you are able to name them. eg ...schoolboys who could identify every car as it passed by... ...officials, who asked not to be identified... The guard had been identified as Viktor Kowalski. (Cobuild, def 1.2)
  • to determine the taxonomic position of (a biological specimen) (W7, def 2b)
  • Biol. to determine to what group (a given specimen) belongs (ACD, def 2)

Omitted here are definitions identifying the meanings of identify in examples like He really identified with the novel's hero, Keats identifies truth with beauty (i.e. treats them as identical), or Wear on your third finger an iron ring, which will identify you. None of these usages seem likely to cause confusion if they occur in our specifications or discussions; in their current state, I don't believe the specifications now use the term identify in either of the first two senses; there are passages which speak of this or that thing being uniquely identified by something else (often by an identifier of some kind).

identical
  • the same or being the same one. (ACD, def 2)
  • the very same. (NWD, def 1)
  • being the same < the ⁓ place we stopped before > (W7, def 1)
  • the same; the very same: said of one thing (or set of things) viewed at different times or in different relations. (Often emphasized by same, very). (OED, def 1)
  • Logic. Said of a proposition, the terms of which denote the same thing; expressing an identity; as the propositions A horse is a horse; man is a human being. (OED, def 3)
  • Alg. Expressing identity, as identical equation, an equation which is true for all values of the literal quantities; as (x + a) ** 2 = x**2 + 2ax + a**2 (OED, def 4a)
  • [Alg.] Effecting identity, as identical operation, an operation which leaves the operand unchanged. (OED, def 4b)

Omitted here are definitions that delineate the broader sense of identical as very very similar (e.g. "exactly alike"); it is not proposed that we use the word in that sense.

The dictionaries consulted for this unsystematic survey include:

ACD
American College Dictionary ed. Clarence L. Barnhart (New York: Random House, 1947)
Cobuild
Cobuild: Collins Cobuild / English Language Dictionary (London, Glasgow: Collins, 1987)
NWD
Webster's New World Dictionary of the American Language, College Edition (Cleveland and New York: The World Publishing Company, 1968)
OED
the Oxford English Dictionary
W7
Webster's Seventh New Collegiate Dictionary, based on Webster's third new international dictionary (Springfield, Mass.: G. & C. Merriam Company, 1963)