In logic, the law (or principle) of identity states simply: 'A is A'. This article gives a concise account of identity

Akman, Varol

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BIBLIOGRAPHYThe bibliographies which follow the entries for indi-vidual philosophers contain a number of studies ofthose single thinkers. In addition the following generalaccounts which survey the movement as a whole maybe consulted.Boucher, David and Andrew Vincent, British Idealismand Political Theory (Edinburgh, 2000).Bradley, James, ‘Hegel in Britain: A Brief History ofBritish Commentary and Attitudes’, The HeythropJournal, 20 (1979), pp. 1–24, 163–82.Den Otter, Sandra, British Idealism and SocialExplanation (Oxford, 1996).Mander, W.J. (ed.), Anglo-American Idealism1865–1927 (Westport, Connecticut and London,2000).Nicholson, P.P., The Political Philosophy of the BritishIdealists (Cambridge, 1990).Quinton, Anthony, ‘Absolute Idealism’, Proceedings ofthe British Academy, 57 (1971), pp. 303–29.Robbins, Peter, The British Hegelians 1875–1925 (NewYork and London, 1982).Sell, A.P.F., Philosophical Idealism and Christian Belief(Cardiff, 1995).Vincent, Andrew and Raymond Plant, Philosophy,Politics and Citizenship: The Life and Thought ofthe British Idealists (Oxford, 1984).W.J. ManderSee also Cambridge Platonism; Common SensePhilosophy; Education, Philosophy of; OxfordPhilosophy; Rationalism; Social SciencesIDENTITYIn LOGIC, the law (or principle) of identity states simply:‘A is A’. Identity is thus the relation that holds betweensomething and itself (and not between something and anyother thing). Questions about identity are relevant to, butdo not exhaust, questions about the much richer subjectof PERSONAL IDENTITY. Though nearly all the philoso-phers mentioned in this article have contributed to dis-cussions of personal identity, sometimes very substan-tially, philosophers such as Derek PARFIT, whose work ismore distinctively in that area, are not discussed.In logic, identity may be defined via the principle ofthe ‘identity of indiscernibles’ (sometimes known as‘Leibniz’s Law’): if A and B have exactly the same prop-erties, then they are identical. John McTaggart EllisMCTAGGART’s ‘dissimilarity of the diverse’ is akin toLeibniz’s Law: if A and B are distinct then there is at leastone property that A has and B does not, or vice versa.Identity may alternatively be introduced as a primitiverelational idiom, in which case the converse principle,the ‘indiscernibility of identicals’, applies: if A is identi-cal with B, then every property that A has B has, and viceversa. Criteria of identity were often debated in the seven-teenth and eighteenth centuries. Thomas HOBBESproposed a puzzle that occupies philosophers to thepresent day: [I]f, for example, that ship of Theseus, concerningthe difference whereof made by continued reparationin taking out the old planks and putting in new, […],were, after all the planks were changed, the samenumerical ship it was at the beginning; and if someman had kept the old planks as they were taken out,and by putting them afterwards together in the sameorder, had made a ship of them, this, without doubt,had also been the same numerical ship with thatwhich was at the beginning; and so there would havebeen two ships numerically the same, which is absurd.(De Corpore, p. 136)Other important contributions came from John LOCKE,Joseph BUTLER, Thomas REID and David HUME. Lockeclaimed that identity does not depend on having thesame atomic particles: ‘[A]n oak growing from a plantto a great tree and lopped, is still the same oak; and acolt grown up to a horse, sometimes fat, sometimeslean, is all the while the same horse’ (Essay). Butlerfamously stated that everything is what it is and notanother thing. Reid noted that ‘wherever identity isreal, it admits of no degrees’ (Essay on the IntellectualPowers of Man, 1785). And Hume had a characteristi-cally psychological take on questions about identity –‘We have a distinct idea of an object that remains invari-able and uninterrupted through a supposed variation oftime; and this idea we call that of identity or sameness’(Treatise) – though he had trouble accounting for thebasis of the idea of identity in experience.Debates about identity revived in the middle of thetwentieth century, perhaps unsurprisingly in a perioddominated by PHILOSOPHY OF LANGUAGE and logic. Forthe average person, to say that a thing is the same asitself appears to be trifling or silly. (Even W.V.O. Quinenotably confesses in his Methods of Logic (1950): ‘Ofwhat use is the notion of identity if identifying an objectwith itself is trivial and identifying it with anything elseis false?’) In ‘On Denoting’, however, Bertrand RUSSELLsuggested how certain identity statements can be bothtrue and informative, by focusing upon statements suchIDEALISM, BRITISH1610as ‘the author of Waverly = Scott,’ in contrast to theuninformative ‘Scott = Scott’. He declared, moreover, inhis Logic and Knowledge (1956): When you say ‘Scott is the author of Waverley’, youare half-tempted to think there are two people, one ofwhom is Scott and the other the author of Waverley,and they happen to be the same. That is obviouslyabsurd, but that is the sort of way one is alwaystempted to deal with identity. E.J. Lemmon, as reported by Cartwright, pointed outthat A = B may be true, even though A has an attrib-ute which B has not. He had in mind what he termeda paradox of intensionality: ‘[T]he morning star,though it is the evening star, has the attribute of beingnecessarily the morning star, which the evening stardoes not have.’ WITTGENSTEIN, moreover, claimed thatthe identity of indiscernibles disallows an option thatinvolves no manifest incoherence at all: two objectshaving all their properties in common. Max BLACKstudied an imaginary universe consisting only of twoexactly resembling spheres – spheres which are qual-itatively impossible to tell apart. It is suggested insuch a completely symmetrical universe that the twospheres would be indiscernible. Contrariwise, Leibnizhad taken the identity of indiscernibles for grantedbecause he thought it followed from other parts of hisMETAPHYSICS. Indeed, in a letter to Samuel CLARKE, hehad deduced the identity of indiscernibles from hisPrinciple of Sufficient Reason.Questions about conditions of identity are related todiscussions of VAGUENESS (which saw important Britishcontributions in the twentieth century). Gareth EVANSgave a formal but terse argument establishing a negativeresponse to the question whether there can be a vagueobject corresponding to the singular term ‘London’,which does not single out a sharply circumscribed localeof England. He observed that if A is vaguely identicalwith B, then there is a fact about A  – i.e. it is vaguelyidentical with B – that B fails to have. But then byLeibniz’s Law, A is not identical with B.Peter GEACH proposed that the notion of absoluteidentity has no merit and that there is only relativeidentity. He put the matter thus in his Logic Matters(1972): ‘When one says “x is identical with y”, this, Ihold, is an incomplete expression; it is short for “x is thesame A as y”, where “A” represents some count noununderstood from the context of utterance – or else, it isjust a vague expression or a half-formed thought’ (LogicMatters, p. 238).David WIGGINS is without doubt the leading present-day theorist working on identity. In Sameness andSubstance Renewed (2001) – in effect, a second editionof his earlier Sameness and Substance – Wiggins offersa tour de force concerning (personal) identity. The twobooks have comparable aims; they argue, for the mostpart against Geach, that identity is absolute. Wigginsnonetheless demonstrates that whenever A = B is true,there is a ‘sortal’ (a Lockean term) F such that A is thesame F as B. BIBLIOGRAPHYBlack, Max, ‘The Identity of Indiscernibles’, Mind,vol. 61 (1952), pp. 153–64.Cartwright, Richard, ‘Identity and Substitutivity’, inhis Philosophical Essays (Cambridge, Mass., 1987),pp. 135–47.Evans, Gareth, ‘Can There Be Vague Objects?’,Analysis, vol. 38 (1978), p. 208.Geach, Peter, Reference and Generality (Ithaca,1962).Hobbes, Thomas, De Corpore, pt. II, chap. II, in W.Molesworth (ed.), The English Works of ThomasHobbes, vol. 1 (1839–45).Hume, David, A Treatise of Human Nature: Being anAttempt to Introduce the Experimental Method ofReasoning into Moral Subjects (1739–40).Locke, John, Essay concerning HumanUnderstanding (1690).Russell, Bertrand, ‘On Denoting’, Mind, vol. 14(1905), pp. 479–93.Strawson, P.F., Individuals: An Essay in DescriptiveMetaphysics (1959).Wiggins, David, Sameness and Substance Renewed(Cambridge, 2001).Varol AkmanILLINGWORTH, John Richardson (1848–1915)John Richardson Illingworth was born in London on 26June 1848 and died in Longworth, Oxfordshire on 21August 1915. He was the son of a prison chaplain inLondon, was educated at Corpus Christi College,Oxford, and became Fellow of Jesus College and tutorat Keble College at the same university in 1872. He wasordained priest in 1876. For reasons of health hewithdrew from academic life to the rectory ofLongworth, Oxfordshire, in 1883, where he remainedfor the rest of his life despite several offers of academicpositions. He declined to give the GIFFORD LECTURES in1902, but received an honorary doctorate of divinityfrom Edinburgh University in the same year. Illingworthbecame a member of the Lux Mundi group and con-tributed two essays to Lux Mundi in 1889.ILLINGWORTH1611

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