9 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. |
| 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. |
| 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. |
| 13365 | Russell's Paradox is a stripped-down version of Cantor's Paradox [Priest,G on Russell] |
| Full Idea: Russell's Paradox is a stripped-down version of Cantor's Paradox. | |
| From: comment on Bertrand Russell (Letters to Frege [1902]) by Graham Priest - The Structure of Paradoxes of Self-Reference §2 |
| 10711 | Russell's paradox means we cannot assume that every property is collectivizing [Potter on Russell] |
| Full Idea: Russell's paradox showed that we cannot consistently assume what is sometimes called the 'naïve comprehension principle', namely that every property is collectivizing. | |
| From: comment on Bertrand Russell (Letters to Frege [1902]) by Michael Potter - Set Theory and Its Philosophy 03.6 |
| 9127 | Russell refuted Frege's principle that there is a set for each property [Russell, by Sorensen] |
| Full Idea: Russell refuted Frege's principle that there is a set for each property. | |
| From: report of Bertrand Russell (Letters to Frege [1902], 1904.12.12) by Roy Sorensen - Vagueness and Contradiction 6.1 | |
| A reaction: This is the principle stumbling block to any attempt to explain properties purely in terms of sets. I would say that Russell proved there couldn't be a set for each predicate. You can't glibly equate proper properties with predicates. |
| 7531 | We don't assert private thoughts; the objects are part of what we assert [Russell] |
| Full Idea: I believe Mont Blanc itself is a component part of what is actually asserted in the proposition 'Mont Blanc is more than 4000 metres high'; we do not assert the thought, which is a private psychological matter, but the object of the thought. | |
| From: Bertrand Russell (Letters to Frege [1902], 1904.12.12), quoted by Ray Monk - Bertrand Russell: Spirit of Solitude Ch.4 | |
| A reaction: This would appear to be pretty much externalism about concepts, given that Russell would accept that other people know much more about Mont Blanc than he does, and their knowledge is included in what he asserts. |
| 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). |
| 23897 | Once money is the main aim, society needs everyone to think wealth is possible [Weil] |
| Full Idea: Money, once it becomes the goal of desires and efforts, cannot tolerate in its domain internal conditions in which it is impossible to be enriched. | |
| From: Simone Weil (The Work of a Free Person [1942], p.134) | |
| A reaction: The possibility for everyone that they might become rich seems basic to capitalism, even though it is utterly impossible. In theory we can all set up small successful businesses, but if they are good they nearly all get squeezed out. |