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. |
| 8825 | It seems impossible to logically deduce physical knowledge from indubitable sense data [Kim] |
| Full Idea: It is agreed on all hands that the classical epistemological project, conceived as one of deductively validating physical knowledge from indubitable sensory data, cannot succeed. | |
| From: Jaegwon Kim (What is 'naturalized epistemology'? [1988], p.304) | |
| A reaction: This is the 'Enlightenment Project', which had a parallel in morality. Kim refers to the difficulty as 'The Humean Predicament'. Hume also hoped that induction might be deductive. One obvious move is to expand from 'deduction' to 'reason'. |
| 9567 | Maths deals with quantities of physical significance, ignoring irrelevant features [Geroch] |
| Full Idea: Mathematics can serve to provide a framework within which one deals only with quantities of physical significance, ignoring other, irrelevant things. | |
| From: Robert Geroch (Mathematical Physics [1985], p.1), quoted by Charles Chihara - A Structural Account of Mathematics 9.8 | |
| A reaction: This is a modern physicist espousing abstractionism, as derided and dismissed by Frege and Geach. It's common sense, really. |
| 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). |