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Single Idea 12130

[filed under theme 9. Objects / F. Identity among Objects / 7. Indiscernible Objects ]

Full Idea

Suppose that a and b have all of their properties in common. a certainly has the property of-being-identical-with-a. So, by supposition, does b. Then a = b.

Gist of Idea

a and b share all properties; so they share being-identical-with-a; so a = b

Source

Baruch Brody (Identity and Essence [1980], 1.2)

Book Ref

Brody,Baruch: 'Identity and Essence' [Princeton 1980], p.9

A Reaction

Brody defends this argument, and seems to think that it proves the identity of indiscernibles. As far as I can see it totally begs the question, since we can only assume that both have the property of being-identical-with-a if we have assumed a = b.

The 38 ideas with the same theme [objects between which no differences are detectable]:

489 Each thing must be in some way unique [Diogenes of Apollonia]
13788 If we made a perfect duplicate of Cratylus, there would be two Cratyluses [Plato]
17175 There cannot be two substances with the same attributes [Spinoza]
17554 There must be some internal difference between any two beings in nature [Leibniz]
5055 No two things are totally identical [Leibniz]
13178 Things in different locations are different because they 'express' those locations [Leibniz]
19412 If two bodies only seem to differ in their position, those different environments will matter [Leibniz]
19411 In nature there aren't even two identical straight lines, so no two bodies are alike [Leibniz]
16504 Two eggs can't be identical, because the same truths can't apply to both of them [Leibniz]
7576 The Identity of Indiscernibles is true of concepts with identical properties, but not of particulars [Kant, by Jolley]
14509 If we ignore differences between water drops, we still distinguish them by their location [Kant]
12033 An object is identical with itself, and no different indiscernible object can share that [Russell/Whitehead, by Adams,RM]
11849 It at least makes sense to say two objects have all their properties in common [Wittgenstein on Russell]
14107 Terms are identical if they belong to all the same classes [Russell]
11095 We should just identify any items which are indiscernible within a given discourse [Quine]
10195 If the universe just held two indiscernibles spheres, that refutes the Identity of Indiscernibles [Black]
5477 One thing can look like something else, without being the something else [Ellis]
12034 If the universe was cyclical, totally indiscernible events might occur from time to time [Adams,RM]
14510 Two events might be indiscernible yet distinct, if there was a universe cyclical in time [Adams,RM]
16455 Black's two globes might be one globe in highly curved space [Adams,RM]
12130 a and b share all properties; so they share being-identical-with-a; so a = b [Brody]
16453 The bundle theory makes the identity of indiscernibles a necessity, since the thing is the properties [Stalnaker]
16505 By the principle of Indiscernibility, a symmetrical object could only be half of itself! [Wiggins]
7566 The Identity of Indiscernibles is really the same as the verification principle [Jolley]
4033 Two pure spheres in non-absolute space are identical but indiscernible [Campbell,K]
3145 The Indiscernibility of Identicals is a truism; but the Identity of Indiscernibles depends on possible identical worlds [Rey]
13379 If two objects are indiscernible across spacetime, how could we decide whether or not they are the same? [Jubien]
13730 The Indiscernibility of Identicals has been a big problem for modal logic [Fitting/Mendelsohn]
4203 Identity of Indiscernibles (same properties, same thing) ) is not Leibniz's Law (same thing, same properties) [Lowe]
13702 The identity of indiscernibles is necessarily true, if being a member of some set counts as a property [Sider]
4476 Most philosophers think that the identity of indiscernibles is false [Moreland]
10198 If only two indiscernible electrons exist, future differences must still be possible [Zimmerman,DW]
10199 Discernible differences at different times may just be in counterparts [Zimmerman,DW]
5746 The Identity of Indiscernibles is contentious for qualities, and trivial for non-qualities [Melia]
4639 Leibniz's Law is about the properties of objects; the Identity of Indiscernibles is about perception of objects [Baggini /Fosl]
7927 At different times Leibniz articulated three different versions of his so-called Law [Macdonald,C]
7928 The Identity of Indiscernibles is false, because it is not necessarily true [Macdonald,C]
18764 The notion of 'property' is unclear for a logical version of the Identity of Indiscernibles [Anderson,CA]