Combining Texts

Ideas for 'Thinking About Mathematics', 'A Structural Account of Mathematics' and 'Occasions of Identity'

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4 ideas

9. Objects / B. Unity of Objects / 3. Unity Problems / b. Cat and its tail
A CAR and its major PART can become identical, yet seem to have different properties [Gallois]
     Full Idea: At t1 there is a whole CAR, and a PART of it, which is everything except the right front wheel. At t2 the wheel is removed, leaving just PART, so that CAR is now PART. But PART was a proper part of CAR, and CAR had the front wheel. Different properties!
     From: André Gallois (Occasions of Identity [1998], 1.II)
     A reaction: [compressed summary] The problem is generated by appealing to Leibniz's Law. My immediate reaction is that this is the sort of trouble you get into if you include such temporal truths about things as 'properties'.
9. Objects / E. Objects over Time / 1. Objects over Time
Gallois hoped to clarify identity through time, but seems to make talk of it impossible [Hawley on Gallois]
     Full Idea: A problem for Gallois is that he leaves us no way to talk about questions of genuine identity through time, and thus undercuts one motivation for his own position.
     From: comment on André Gallois (Occasions of Identity [1998]) by Katherine Hawley - How Things Persist 5.8
     A reaction: Gallois seems to need a second theory of identity to support his Occasional Identity theory. Two things need an identity each, before we can say that the two identities coincide. (Time to read Gallois!)
9. Objects / F. Identity among Objects / 3. Relative Identity
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.
9. Objects / F. Identity among Objects / 6. Identity between Objects
Occasional Identity: two objects can be identical at one time, and different at others [Gallois, by Hawley]
     Full Idea: Gallois' Occasional Identity Thesis is that objects can be identical at one time without being identical at all times.
     From: report of André Gallois (Occasions of Identity [1998]) by Katherine Hawley - How Things Persist 5.4
     A reaction: The analogy is presumably with two crossing roads being identical at one place but not at others. It is a major misunderstanding to infer from Special Relativity that time is just like space.