display all the ideas for this combination of texts
3 ideas
18121 | In logic a proposition means the same when it is and when it is not asserted [Bostock] |
Full Idea: In Modus Ponens where the first premise is 'P' and the second 'P→Q', in the first premise P is asserted but in the second it is not. Yet it must mean the same in both premises, or it would be guilty of the fallacy of equivocation. | |
From: David Bostock (Philosophy of Mathematics [2009], 7.2) | |
A reaction: This is Geach's thought (leading to an objection to expressivism in ethics, that P means the same even if it is not expressed). |
3403 | We assume people believe the obvious logical consequences of their known beliefs [Kim] |
Full Idea: We attribute to a subject beliefs that are obvious logical consequences of beliefs already attributed to him. | |
From: Jaegwon Kim (Philosophy of Mind [1996], p.135) | |
A reaction: Depends what you mean by 'obvious'. Presumably they must be judged obvious to the believer, but only if they have thought of them. We can't believe all the simple but quirky implications of our beliefs. |
3402 | If someone says "I do and don't like x", we don't assume a contradiction [Kim] |
Full Idea: If someone says "I do and I don't like x", we do not take her to be expressing a literally contradictory belief. | |
From: Jaegwon Kim (Philosophy of Mind [1996], p.135) | |
A reaction: It might mean 'one minute I like it, and the next minute I don't', where there seems to be a real contradiction, with a time factor. You can't sustain both preferences with conviction. |