Single Idea 22279

[catalogued under 5. Theory of Logic / B. Logical Consequence / 3. Deductive Consequence |-]

Full Idea

Natural deduction systems generally depend on conditional proof, but for Frege everything is asserted unconditionally. The modern turnstile |- is allowed to have antecedents, and hence to represent inference rather than Frege's judgement sign |---.

Gist of Idea

Frege's sign |--- meant judgements, but the modern |- turnstile means inference, with intecedents


Michael Potter (The Rise of Analytic Philosophy 1879-1930 [2020], 03 'Axioms')

Book Reference

Potter,Michael: 'The Rise of Anaytic Philosophy 1879-1930' [Routledge 2020], p.28

A Reaction

[compressed] Shockingly, Frege's approach seems more psychological than the modern approach. I would say that the whole point of logic is that it has to be conditional, because the truth of the antecedents is irrelevant.