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Single Idea 5746

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

Full Idea

If the Identity of Indiscernibles is referring to qualitative properties, such as 'being red' or 'having mass', it is contentious; if it is referring to non-qualitative properties, such as 'member of set s' or 'brother of a', it is true but trivial.

Gist of Idea

The Identity of Indiscernibles is contentious for qualities, and trivial for non-qualities

Source

Joseph Melia (Modality [2003], Ch.3 n 11)

Book Ref

Melia,Joseph: 'Modality' [Acumen 2003], p.177

A Reaction

I would say 'false' rather than 'contentious'. No one has ever offered a way of distinguishing two electrons, but that doesn't mean there is just one (very busy) electron. The problem is that 'indiscernible' is only an epistemological concept.

The 17 ideas from 'Modality'

5734 Possible worlds make it possible to define necessity and counterfactuals without new primitives [Melia]
5732 'De re' modality is about things themselves, 'de dicto' modality is about propositions [Melia]
5739 Sometimes we want to specify in what ways a thing is possible [Melia]
5742 In possible worlds semantics the modal operators are treated as quantifiers [Melia]
5743 If possible worlds semantics is not realist about possible worlds, logic becomes merely formal [Melia]
5740 Second-order logic needs second-order variables and quantification into predicate position [Melia]
5741 If every model that makes premises true also makes conclusion true, the argument is valid [Melia]
5735 Maybe names and predicates can capture any fact [Melia]
5736 No sort of plain language or levels of logic can express modal facts properly [Melia]
5737 Predicate logic has connectives, quantifiers, variables, predicates, equality, names and brackets [Melia]
5738 We may be sure that P is necessary, but is it necessarily necessary? [Melia]
5744 First-order predicate calculus is extensional logic, but quantified modal logic is intensional (hence dubious) [Melia]
5746 The Identity of Indiscernibles is contentious for qualities, and trivial for non-qualities [Melia]
5748 We accept unverifiable propositions because of simplicity, utility, explanation and plausibility [Melia]
5749 Possible worlds could be real as mathematics, propositions, properties, or like books [Melia]
5750 Consistency is modal, saying propositions are consistent if they could be true together [Melia]
5751 The truth of propositions at possible worlds are implied by the world, just as in books [Melia]