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Ideas for 'works', 'Mathematics is Megethology' and 'Logical Properties'

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9 ideas

5. Theory of Logic / D. Assumptions for Logic / 4. Identity in Logic
In 'x is F and x is G' we must assume the identity of x in the two statements [McGinn]
     Full Idea: If we say 'for some x, x is F and x is G' we are making tacit appeal to the idea of identity in using 'x' twice here: it has to be the same object that is both F and G.
     From: Colin McGinn (Logical Properties [2000], Ch.1)
     A reaction: This may well be broadened to any utterances whatsoever. The only remaining question is to speculate about whether it is possible to think without identities. The Hopi presumably gave identity to processes rather objects. How does God think?
Both non-contradiction and excluded middle need identity in their formulation [McGinn]
     Full Idea: To formulate the law of non-contradiction ('nothing can be both F and non-F') and the law of excluded middle ('everything is either F or it is not-F'), we need the concept of identity (in 'nothing' and 'everything').
     From: Colin McGinn (Logical Properties [2000], Ch.1)
     A reaction: Two good examples in McGinn's argument that identity is basic to all thinking. But the argument also works to say that necessity is basic (since both laws claim it) and properties are basic. Let's just declare everything 'basic', and we can all go home.
Identity is unitary, indefinable, fundamental and a genuine relation [McGinn]
     Full Idea: I have endorsed four main theses about identity: it is unitary, it is indefinable, it is fundamental, and it is a genuine relation
     From: Colin McGinn (Logical Properties [2000], Ch.1)
     A reaction: That it is fundamental to our thinking seems certain (but to all possible thought?). That it is a relation looks worth questioning. One might challenge unitary by comparing the identity of numbers, values, electrons and continents. I can't define it.
5. Theory of Logic / E. Structures of Logic / 1. Logical Form
For Aristotle, the subject-predicate structure of Greek reflected a substance-accident structure of reality [Aristotle, by O'Grady]
     Full Idea: Aristotle apparently believed that the subject-predicate structure of Greek reflected the substance-accident nature of reality.
     From: report of Aristotle (works [c.330 BCE]) by Paul O'Grady - Relativism Ch.4
     A reaction: We need not assume that Aristotle is wrong. It is a chicken-and-egg. There is something obvious about subject-predicate language, if one assumes that unified objects are part of nature, and not just conventional.
5. Theory of Logic / E. Structures of Logic / 6. Relations in Logic
We can use mereology to simulate quantification over relations [Lewis]
     Full Idea: We can simulate quantification over relations using megethology. Roughly, a quantifier over relations is a plural quantifier over things that encode ordered pairs by mereological means.
     From: David Lewis (Mathematics is Megethology [1993], p.18)
     A reaction: [He credits this idea to Burgess and Haven] The point is to avoid second-order logic, which quantifies over relations as ordered n-tuple sets.
5. Theory of Logic / G. Quantification / 1. Quantification
The quantifier is overrated as an analytical tool [McGinn]
     Full Idea: The quantifier has been overrated as a tool of logical and linguistic analysis.
     From: Colin McGinn (Logical Properties [2000], Pref)
     A reaction: I find this proposal quite thrilling. Twentieth century analytical philosophy has been in thrall to logic, giving the upper hand in philosophical discussion to the logicians, who are often not very good at philosophy.
Existential quantifiers just express the quantity of things, leaving existence to the predicate 'exists' [McGinn]
     Full Idea: What the existential quantifier does is indicate the quantity of things in question - it says that some are; it is left up to the predicate 'exists' to express existence.
     From: Colin McGinn (Logical Properties [2000], Ch.2)
     A reaction: This seems right. The whole quantification business seems like a conjuring trick to conceal the embarrassingly indefinable and 'metaphysical' notion of 'existence'. Cf Idea 7697.
5. Theory of Logic / G. Quantification / 3. Objectual Quantification
'Partial quantifier' would be a better name than 'existential quantifier', as no existence would be implied [McGinn]
     Full Idea: We would do much better to call 'some' the 'partial quantifier' (rather than the 'existential quantifier'), on analogy with the universal quantifier - as neither of them logically implies existence.
     From: Colin McGinn (Logical Properties [2000], Ch.2)
     A reaction: Like McGinn's other suggestions in this chapter, this strikes me as a potentially huge clarification in linguistic analysis. I wait with interest to see whether the philosophical logicians take it up. I bet they don't.
5. Theory of Logic / G. Quantification / 7. Unorthodox Quantification
We need an Intentional Quantifier ("some of the things we talk about.."), so existence goes into the proposition [McGinn]
     Full Idea: We could introduce an 'intentional quantifier' (Ix) which means 'some of the things we talk about..'; we could then say 'some of the things we talk about are F and exist' (Ix, x is F and x exists).
     From: Colin McGinn (Logical Properties [2000], Ch.2)
     A reaction: This immediately strikes me as a promising contribution to the analytical toolkit. McGinn is supporting his view that existence is a predicate, and so belongs inside the proposition, not outside.