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
Source
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.