11148 | Deduction is when we suppose one thing, and another necessarily follows [Aristotle] |
18277 | If q implies p, that is justified by q and p, not by some 'laws' of inference [Wittgenstein] |
13623 | The syntactic turnstile |- φ means 'there is a proof of φ' or 'φ is a theorem' [Bostock] |
13722 | A 'theorem' is an axiom, or the last line of a legitimate proof [Sider] |
10752 | Γ |- S says S can be deduced from Γ; Γ |= S says a good model for Γ makes S true [Rossberg] |
18808 | Normal deduction presupposes the Cut Law [Rumfitt] |