7 ideas
| 11211 | If a sound conclusion comes from two errors that cancel out, the path of the argument must matter [Rumfitt] |
| Full Idea: If a designated conclusion follows from the premisses, but the argument involves two howlers which cancel each other out, then the moral is that the path an argument takes from premisses to conclusion does matter to its logical evaluation. | |
| From: Ian Rumfitt ("Yes" and "No" [2000], II) | |
| A reaction: The drift of this is that our view of logic should be a little closer to the reasoning of ordinary language, and we should rely a little less on purely formal accounts. |
| 7334 | Anti-realism needs an intuitionist logic with no law of excluded middle [Dummett, by Miller,A] |
| Full Idea: Dummett argues that antirealism implies that classical logic must be given up in favour of some form of intuitionistic logic that does not have the law of excluded middle as a theorem. | |
| From: report of Michael Dummett (works [1970]) by Alexander Miller - Philosophy of Language 9.4 | |
| A reaction: Only realists can think every proposition is either true or false, even if it is beyond the bounds of our possible knowledge (e.g. tiny details from remote history). Personally I think "Plato had brown eyes" is either true or false. |
| 11212 | The sense of a connective comes from primitively obvious rules of inference [Rumfitt] |
| Full Idea: A connective will possess the sense that it has by virtue of its competent users' finding certain rules of inference involving it to be primitively obvious. | |
| From: Ian Rumfitt ("Yes" and "No" [2000], III) | |
| A reaction: Rumfitt cites Peacocke as endorsing this view, which characterises the logical connectives by their rules of usage rather than by their pure semantic value. |
| 11210 | Standardly 'and' and 'but' are held to have the same sense by having the same truth table [Rumfitt] |
| Full Idea: If 'and' and 'but' really are alike in sense, in what might that likeness consist? Some philosophers of classical logic will reply that they share a sense by virtue of sharing a truth table. | |
| From: Ian Rumfitt ("Yes" and "No" [2000]) | |
| A reaction: This is the standard view which Rumfitt sets out to challenge. |
| 3303 | For anti-realists there are no natural distinctions between objects [Dummett, by Benardete,JA] |
| Full Idea: Dummett says that anti-realism offers us a picture of reality as an amorphous lump not yet articulated into discrete objects. | |
| From: report of Michael Dummett (works [1970]) by José A. Benardete - Metaphysics: the logical approach Ch.2 | |
| A reaction: This might be called 'weak' anti-realism, where 'strong' anti-realism is the view that reality is quite unknowable, and possibly non-existent. |
| 11214 | We learn 'not' along with affirmation, by learning to either affirm or deny a sentence [Rumfitt] |
| Full Idea: The standard view is that affirming not-A is more complex than affirming the atomic sentence A itself, with the latter determining its sense. But we could learn 'not' directly, by learning at once how to either affirm A or reject A. | |
| From: Ian Rumfitt ("Yes" and "No" [2000], IV) | |
| A reaction: [compressed] This seems fairly anti-Fregean in spirit, because it looks at the psychology of how we learn 'not' as a way of clarifying what we mean by it, rather than just looking at its logical behaviour (and thus giving it a secondary role). |
| 20543 | 'Social justice' is a confused idea, and inequalities need no justification [Hayek, by Swift] |
| Full Idea: Hayek thinks the whole idea of social justice involves a philosophical mistake, so that inequality doesn't really need justification in the first place. | |
| From: report of F.A. Hayek (The Mirage of Social Justice [1976]) by Adam Swift - Political Philosophy (3rd ed) 1 'Conc' | |
| A reaction: It is certainly hard to justify the claim that the state of nature involves equality, making its disturbance in need of justification. But surely inequalities in government policy (such as differential income tax) need justification? |