9 ideas
| 15457 | Interdefinition is useless by itself, but if we grasp one separately, we have them both [Lewis] |
| Full Idea: All circles of interdefinition are useless by themselves. But if we reach one of the interdefined pair, then we have them both. | |
| From: David Lewis (Defining 'Intrinsic' (with Rae Langton) [1998], IV) |
| 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. |
| 15400 | We must avoid circularity between what is intrinsic and what is natural [Lewis, by Cameron] |
| Full Idea: Lewis revised his analysis of duplication because he had assumed that as a matter of necessity perfectly natural properties are intrinsic, and that necessarily how a thing is intrinsically is determined completely by the natural properties it has. | |
| From: report of David Lewis (Defining 'Intrinsic' (with Rae Langton) [1998]) by Ross P. Cameron - Intrinsic and Extrinsic Properties 'Analysis' | |
| A reaction: [This compares Lewis 1986:61 with Langton and Lewis 1998] I am keen on both intrinsic and on natural properties, but I have not yet confronted this little problem. Time for a displacement activity, I think.... |
| 15458 | A property is 'intrinsic' iff it can never differ between duplicates [Lewis] |
| Full Idea: A property is 'intrinsic' iff it never can differ between duplicates; iff whenever two things (actual or possible) are duplicates, either both of them have the property or both of them lack it. | |
| From: David Lewis (Defining 'Intrinsic' (with Rae Langton) [1998], IV) | |
| A reaction: This leaves me wondering how one could arrive at a precise definition of 'duplicates'. Can it be done without mentioning that they have the same intrinsic properties? |
| 15459 | Ellipsoidal stars seem to have an intrinsic property which depends on other objects [Lewis] |
| Full Idea: The property of being an ellipsoidal star would seem offhand to be a basic intrinsic property, but it is incompatible (nomologically) with being an isolated object. | |
| From: David Lewis (Defining 'Intrinsic' (with Rae Langton) [1998], V) | |
| A reaction: Another nice example from Lewis. It makes you wonder whether the intrinsic/extrinsic distinction should go. Modern physics, with its 'entanglements', doesn't seem to suit the distinction. |
| 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). |
| 22450 | If moral systems can't judge other moral systems, then moral relativism is true [Williams,B, by Foot] |
| Full Idea: If some societies with divergent moral systems merely confront each other, having no use for the assertion that their own systems are true and the others false except to mark the system to which they adhere, then relativism is a true theory of morality. | |
| From: report of Bernard Williams (The Truth in Relativism [1974]) by Philippa Foot - Moral Relativism p.3 | |
| A reaction: 'Having no use for' an assertion is not the same as the assertion being impossible. Some liberal cultures refuse to criticise others because their highest value is tolerance, even when the target culture wholly contradicts the critics' other values. |