6 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. |
| 6901 | Understanding is needed for imagination, just as much as the other way around [Betteridge] |
| Full Idea: Although it might be right to say that imagination is required in order to make reasoning and understanding possible, this also works the other way, as imagination cannot occur without some prior understanding. | |
| From: Alex Betteridge (talk [2005]), quoted by PG - Db (ideas) | |
| A reaction: This strikes me as a very illuminating remark, particularly for anyone who aspires to draw a simplified flowdiagram of the mind showing logical priority between its various parts. In fact, the parts are interdependent. Maybe imagination is understanding. |
| 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). |
| 18639 | If we assess what people would buy in an imaginary insurance market, our taxes could copy it [Dworkin, by Kymlicka] |
| Full Idea: If we can make sense of a hypothetical insurance market, and find a determinate answer to the question of what insurance people would buy in it, then we could use the tax system to duplicate the results. | |
| From: report of Ronald Dworkin (A Matter of Principle [1985]) by Will Kymlicka - Contemporary Political Philosophy (1st edn) 2.4.b | |
| A reaction: This is a nice alternative from Dworkin to Rawls's 'veil of ignorance' approach. |