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Single Idea 19057

[filed under theme 5. Theory of Logic / G. Quantification / 1. Quantification ]

Full Idea

Classical quantification represents an infinite conjunction or disjunction, and the truth-value is determined by the infinite sum or product of the instances ....but this presupposes that all the instances already possess determinate truth-values.

Gist of Idea

Classical quantification is an infinite conjunction or disjunction - but you may not know all the instances

Source

Michael Dummett (The philosophical basis of intuitionist logic [1973], p.246)

Book Ref

Dummett,Michael: 'Truth and Other Enigmas' [Duckworth 1978], p.246


A Reaction

In the case of the universal quantifier, Dummett is doing no more than citing the classic empiricism objection to induction - that you can't make the universal claim if you don't know all the instances. The claim is still meaningful, though.


The 5 ideas from 'The philosophical basis of intuitionist logic'

Dummett says classical logic rests on meaning as truth, while intuitionist logic rests on assertability [Dummett, by Kitcher]
Meaning as use puts use beyond criticism, and needs a holistic view of language [Dummett]
Stating a sentence's truth-conditions is just paraphrasing the sentence [Dummett]
If a sentence is effectively undecidable, we can never know its truth conditions [Dummett]
Classical quantification is an infinite conjunction or disjunction - but you may not know all the instances [Dummett]