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Single Idea 9552

[filed under theme 5. Theory of Logic / K. Features of Logics / 2. Consistency ]

Full Idea

In first-order logic a set of sentences is 'consistent' iff there is an interpretation (or structure) in which the set of sentences is true. ..For Frege, though, a set of sentences is consistent if it is not possible to deduce a contradiction from it.

Gist of Idea

Sentences are consistent if they can all be true; for Frege it is that no contradiction can be deduced

Source

Charles Chihara (A Structural Account of Mathematics [2004], 02.1)

Book Ref

Chihara,Charles: 'A Structural Account of Mathematics' [OUP 2004], p.33

A Reaction

The first approach seems positive, the second negative. Frege seems to have a higher standard, which is appealing, but the first one seems intuitively right. There is a possible world where this could work.

The 17 ideas from 'A Structural Account of Mathematics'

10192 We can replace existence of sets with possibility of constructing token sentences [Chihara, by MacBride]
9547 Mathematical entities are causally inert, so the causal theory of reference won't work for them [Chihara]
9550 We only know relational facts about the empty set, but nothing intrinsic [Chihara]
9551 What is special about Bill Clinton's unit set, in comparison with all the others? [Chihara]
9549 The set theorist cannot tell us what 'membership' is [Chihara]
9552 Sentences are consistent if they can all be true; for Frege it is that no contradiction can be deduced [Chihara]
9553 Analytic geometry gave space a mathematical structure, which could then have axioms [Chihara]
9559 If a successful theory confirms mathematics, presumably a failed theory disconfirms it? [Chihara]
9561 The mathematics of relations is entirely covered by ordered pairs [Chihara]
9562 In simple type theory there is a hierarchy of null sets [Chihara]
9563 A pack of wolves doesn't cease when one member dies [Chihara]
9566 No scientific explanation would collapse if mathematical objects were shown not to exist [Chihara]
9568 I prefer the open sentences of a Constructibility Theory, to Platonist ideas of 'equivalence classes' [Chihara]
9571 ZFU refers to the physical world, when it talks of 'urelements' [Chihara]
9573 The null set is a structural position which has no other position in membership relation [Chihara]
9572 Realists about sets say there exists a null set in the real world, with no members [Chihara]
9574 'Gunk' is an individual possessing no parts that are atoms [Chihara]