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9. Objects / F. Identity among Objects / 3. Relative Identity

[identity can only ever be in respect of some feature]

18 ideas
As an infant, Socrates was not the same body, but he was the same human being [Hobbes]
     Full Idea: It makes a great difference to ask concerning Socrates whether he is the same human being or whether he is the same body. For his body, when he is old, cannot be the same it was when he was an infant. …He can, however, be the same human being.
     From: Thomas Hobbes (De Corpore (Elements, First Section) [1655], 2.11.07)
     A reaction: This is not commitment to full (Geachian) relative identity, but it notes the problem.
Same person, man or substance are different identities, belonging to different ideas [Locke]
     Full Idea: It is one thing to be the same substance, another the same man, and a third the same person, if Person, Man and Substance are three names standing for three different ideas; for such as is the idea belonging to the name, such must be the identity.
     From: John Locke (Essay Conc Human Understanding (2nd Ed) [1694], 2.27.07)
     A reaction: It might be better to say that two things can only be 'the same' in some respect. You can say 'in some respects they are the same', without citing the respects.
Geach denies Frege's view, that 'being the same F' splits into being the same and being F [Perry on Frege]
     Full Idea: Frege's position is that 'being the same F as' splits up into a general relation and an assertion about the referent ('being the same' and 'being an F'). This is what Geach denies, when he says there is no such thing as being 'just the same'.
     From: comment on Gottlob Frege (Grundlagen der Arithmetik (Foundations) [1884]) by John Perry - The Same F I
     A reaction: It looks as if you can take your pick - whether two things are perfectly identical, or whether they are identical in some respect. Get an unambiguous proposition before you begin the discussion. Identify referents, not kinds of identity, says Perry.
Things can only be judged the 'same' by citing some respect of sameness [Goodman]
     Full Idea: Identification rests upon organization into entities and kinds. The response to the question 'Same or not the same?' must always be 'Same what?'. ...Identity or constancy in a world is identity with respect to what is within that world as organised.
     From: Nelson Goodman (Ways of Worldmaking [1978], 1.4a)
     A reaction: And the gist of his book is that 'organised' is done by us, not by the world. He seems to be committed to the full Geachean relative identity, rather than the mere Wigginsian relative individuation. An unfashionable view!
Denial of absolute identity has drastic implications for logic, semantics and set theory [Wasserman on Geach]
     Full Idea: Geach's denial of absolute identity has drastic implications for logic, semantics and set theory. He must deny the axiom of extensionality in set theory, for example.
     From: comment on Peter Geach (Reference and Generality (3rd ed) [1980]) by Ryan Wasserman - Material Constitution 6
     A reaction: I'm beginning to think we have two entirely different concepts here - the logicians' and mathematicians' notion of when two things are identical, and the ordinary language concept of two things being 'the same'. 'We like the same music'.
Identity is relative. One must not say things are 'the same', but 'the same A as' [Geach]
     Full Idea: Identity is relative. When one says 'x is identical with y' this is an incomplete expression. It is short for 'x is the same A as y', where 'A' represents some count noun understood from the context of utterance.
     From: Peter Geach (Reference and Generality (3rd ed) [1980], p.39), quoted by John Perry - The Same F I
     A reaction: Perry notes that Geach's view is in conscious opposition to Frege, who had a pure notion of identity. We say 'they are the same insofar as they are animals', but not 'they are the same animal'. Perfect identity involves all possible A's.
If diachronic identities need covering concepts, why not synchronic identities too? [Ayers]
     Full Idea: Why are covering concepts required for diachronic identities, when they must be supposed unnecessary for synchronic identities?
     From: M.R. Ayers (Individuals without Sortals [1974], 'Prob')
An act of ostension doesn't seem to need a 'sort' of thing, even of a very broad kind [Cartwright,R]
     Full Idea: For an ostension to be successful it is surely not necessary that I gather what sort of object it is you have indicated, such as being a horse or a zebra. I may even gather which thing you have indicated without knowing that it is a mammal or even alive.
     From: Richard Cartwright (Some Remarks on Essentialism [1968], p.157)
     A reaction: This nicely articulates the objection I have always felt to Geach's relative identity. 'Oh my God, what the hell is THAT???' is probably going to be a successful act of verbal reference, even while explicitly denying all knowledge of sortals.
Statements of 'relative identity' are really statements of resemblance [Perry]
     Full Idea: Statements of 'relative' identity are not identity statements at all, but what I would prefer to call 'statements of resemblance' or 'common property staztements'.
     From: John Perry (The Same F [1970], n12)
     A reaction: This seems like a neat way to sweep the problem from our sight. There remains a nervous metaphysical problem, though, because something seems to be identical when we spot a resemblance. Even two shades of red have something identical in them.
Relative Identity is incompatible with the Indiscernibility of Identicals [Wiggins, by Strawson,P]
     Full Idea: Wiggins argues that Geach's Relative Identity is incompatible with the formal properties of identity, which include, besides transitivity, symmetry and reflexivity, the complete community of properties defined by the Indiscernibility of Identicals.
     From: report of David Wiggins (Sameness and Substance Renewed [2001]) by Peter F. Strawson - Review of 'Sameness and Substance' p.603
     A reaction: The tricky part is that Wiggins then goes on to say that identity depends on sortals, which sounds very close to the Geach view. I find disentangling them tricky. See Idea 14363 for a helpful comment from Strawson.
Relativity of Identity makes identity entirely depend on a category [Wiggins]
     Full Idea: The thesis of Relativity of Identity (which I steadfastly oppose) ..suggests that it makes all the difference to keeping track of continuants through space and time which concept one subsumes something under.
     From: David Wiggins (Sameness and Substance Renewed [2001], 1.1)
     A reaction: [Geach I take to be the villain of this idea] The point is that identity is entirely relative to the sortal concept, where Wiggins wants to make identity a combination of the object itself and our concept of it (I think).
To identify two items, we must have a common sort for them [Wiggins]
     Full Idea: As a necessary condition of the truth of an identity claim, some common sort f will have to be found to which they each belong. That is the point at which the primary question of identity can come into focus.
     From: David Wiggins (Sameness and Substance Renewed [2001], 2.2)
     A reaction: This is the plainest English expression I can find of Wiggins's main thesis. He maintains this thesis, while adamantly denying the idea that identity consists entirely of falling under a concept.
Gallois is committed to identity with respect to times, and denial of simple identity [Gallois, by Sider]
     Full Idea: Gallois's core claim is that the identity relation holds with respect to times, ...and he must claim that there is no such thing as the relation of identity simpliciter.
     From: report of André Gallois (Occasions of Identity [1998]) by Theodore Sider - Four Dimensionalism 5.5
     A reaction: Gallois is essentially responding to the statue and clay problem, but it seems a bit drastic to entirely change our concept of two things being identical, such as Hesperus and Phosphorus. 'Identity' seems to have several meanings; let's sort them out.
A clear idea of the kind of an object must precede a criterion of identity for it [Lowe]
     Full Idea: As Locke clearly understood, one must first have a clear conception of what kind of object one is dealing with in order to extract a criterion of identity for objects of that kind from that conception.
     From: E.J. Lowe (The Possibility of Metaphysics [1998], 10.3)
     A reaction: Archaeologist face objects which they can number, remember and take pride in, without having a clue what kind of thing they are dealing with. The two processes may not be entirely distinct.
We sometimes apply identity without having a real criterion [Hale]
     Full Idea: Not every (apparent) judgement of identity involves application of anything properly describable as a criterion of identity, ...such as being able to pronounce that mercy is the quality of being merciful.
     From: Bob Hale (Abstract Objects [1987], Ch.2.II)
     A reaction: This suggests some distinction between internal criteria (e.g. grammatical, conceptual) and external criteria (existent, sensed).
We aren't clear about 'same stuff as this', so a principle of individuation is needed to identify it [Sidelle]
     Full Idea: Independent of conventions, no definite sense can be given to the notion of 'the same stuff as this'. So reference-fixing must include some principle of individuation to determine the aspects of sameness for the identity referred to.
     From: Alan Sidelle (Necessity, Essence and Individuation [1989], Ch.6)
     A reaction: Is he really saying that we don't understand 'same stuff as this'? Surely animals can manage that, and they are not famous for their conventions. Sidelle has fallen into the sortalist trap, I think.
If identity is based on 'true of X' instead of 'property of X' we get the Masked Man fallacy ('I know X but not Y') [Baggini /Fosl, by PG]
     Full Idea: The Masked Man fallacy is when Leibniz's Law is taken as 'X and Y are identical if what is true of X is true of Y' (rather than being about properties). Then 'I know X' but 'I don't know Y' (e.g. my friend wearing a mask) would make X and Y non-identical.
     From: report of J Baggini / PS Fosl (The Philosopher's Toolkit [2003], §3.17) by PG - Db (ideas)
     A reaction: As the book goes on to explain, Descartes is guilty of this when arguing that I necessarily know my mind but not my body, so they are different. Seems to me that Kripke falls into the same trap.
Relative identity may reject transitivity, but that suggests that it isn't about 'identity' [Wasserman]
     Full Idea: If the relative identity theorist denies transitivity (to deal with the Ship of Theseus, for example), this would make us suspect that relativised identity relations are not identity relations, since transitivity seems central to identity.
     From: Ryan Wasserman (Material Constitution [2009], 6)
     A reaction: The problem here, I think, focuses on the meaning of the word 'same'. One change of plank leaves you with the same ship, but that is not transitive. If 'identical' is too pure to give the meaning of 'the same' it's not much use in discussing the world.