18 ideas
| 3993 | Arguments are nearly always open to challenge, but they help to explain a position rather than force people to believe [Lewis] |
| Full Idea: Philosophical arguments are never incontrovertible - well, hardly ever. Their purpose is to help expound a position, not to coerce agreement. | |
| From: David Lewis (Lewis: reduction of mind (on himself) [1994], p.419) | |
| A reaction: A bit over-cautious, perhaps. Most philosophers are converted to a position when they hear a single key argument, though it is probably 'tipping the balance' of previous discussions. |
| 6343 | For Russell, both propositions and facts are arrangements of objects, so obviously they correspond [Horwich on Russell] |
| Full Idea: Given Russell's notion of a proposition, as an arrangement of objects and properties, it is hard to see how there could be any difference at all between such a proposition and the fact corresponding to it, since they each involve the same arrangement. | |
| From: comment on Bertrand Russell (On the Nature of Truth and Falsehood [1910]) by Paul Horwich - Truth (2nd edn) Ch.7.35 | |
| A reaction: This seems a little unfair, given that Russell (in 1912) uses the notion now referred to as 'congruence', so that the correspondence is not in the objects and properties, but in how they are 'ordered', which may differ between proposition and fact. |
| 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. |
| 3990 | The whole truth supervenes on the physical truth [Lewis] |
| Full Idea: The whole truth supervenes on the physical truth. | |
| From: David Lewis (Lewis: reduction of mind (on himself) [1994], p.412) | |
| A reaction: This seems to me the central truth about brains, and we should not be lured into abandoning it. We should not, however, exclude the possibility that there is a non-physical reality. |
| 3991 | Where pixels make up a picture, supervenience is reduction [Lewis] |
| Full Idea: In the case of millions of pixels making up a picture on a computer screen, the supervenience is reduction. | |
| From: David Lewis (Lewis: reduction of mind (on himself) [1994], p.414) | |
| A reaction: Since 'supervenience' seems a suspect relationship about which no one is clear, this is a point very much worth making. |
| 3995 | A mind is an organ of representation [Lewis] |
| Full Idea: A mind is an organ of representation. | |
| From: David Lewis (Lewis: reduction of mind (on himself) [1994], p.421) | |
| A reaction: This does not seem to necessarily involve awareness, so it seems to put intentionality at the centre of things. It is a good slogan. |
| 3994 | Human pain might be one thing; Martian pain might be something else [Lewis] |
| Full Idea: Human pain might be one thing. Martian pain might be something else. | |
| From: David Lewis (Lewis: reduction of mind (on himself) [1994], p.420) | |
| A reaction: A key suggestion in support of type-type physicalism, and against the multiple realisability objection to the identity theory |
| 3989 | I am a reductionist about mind because I am an a priori reductionist about everything [Lewis] |
| Full Idea: My reductionism about mind began as part of an a priori reductionism about everything. | |
| From: David Lewis (Lewis: reduction of mind (on himself) [1994], p.412) | |
| A reaction: He says this is 'a priori' to avoid giving hostages to fortune, but I think is the best explanation of the total evidence facing us |
| 3992 | Folk psychology makes good predictions, by associating mental states with causal roles [Lewis] |
| Full Idea: Folk psychology is a powerful instrument of prediction, …which associates with each mental state a typical causal role. | |
| From: David Lewis (Lewis: reduction of mind (on himself) [1994], p.416) | |
| A reaction: This seems a good account of why we should take folk psychology very seriously, even if it is sometimes wrong (e.g. about people who are mentally ill). |
| 3996 | Folk psychology doesn't say that there is a language of thought [Lewis] |
| Full Idea: I don't believe that folk psychology says there is a language of thought. | |
| From: David Lewis (Lewis: reduction of mind (on himself) [1994], p.422) | |
| A reaction: This is aimed at Jerry Fodor. Certainly folk psychology is a strong theory, but a so-called 'language of thought' (the brain's machine code) seems a much weaker one. |
| 3998 | If you don't share an external world with a brain-in-a-vat, then externalism says you don't share any beliefs [Lewis] |
| Full Idea: If the famous brain in a bottle is your exact duplicate in brain states, but only experiences the computer's virtual reality, so that you share no objects of acquaintance, then according to externalists you share no beliefs whatsoever. | |
| From: David Lewis (Lewis: reduction of mind (on himself) [1994], p.424) | |
| A reaction: A very nice reductio ad absurdum of the idea that all concepts and beliefs have external meaning. |
| 3997 | Nothing shows that all content is 'wide', or that wide content has logical priority [Lewis] |
| Full Idea: There is nothing to support the thesis that wide content is the only kind of content, or that it is any way pre-eminent or basic. | |
| From: David Lewis (Lewis: reduction of mind (on himself) [1994], p.424) | |
| A reaction: The idea that all content is 'wide' seems quite wrong. We can't all be wrong about the meaning of a word, because the underlying facts have not yet been discovered. |
| 3999 | A spontaneous duplicate of you would have your brain states but no experience, so externalism would deny him any beliefs [Lewis] |
| Full Idea: According to externalists, Davidson's 'swampman' is your exact duplicate in brains states, but hasn't had time to become acquainted with much, so he has virtually no beliefs. | |
| From: David Lewis (Lewis: reduction of mind (on himself) [1994], p.425) | |
| A reaction: An implausible fantasy, but it does highlight the fact that beliefs and concepts are primarily internal states. |
| 4000 | Wide content derives from narrow content and relationships with external things [Lewis] |
| Full Idea: Wide content is derivative, a product of narrow content and relationships of acquaintance with external things. | |
| From: David Lewis (Lewis: reduction of mind (on himself) [1994], p.430) | |
| A reaction: I would say: content is a mental state, but it is created and fixed by a community, and wide content is the part fixed by experts in the community. We can all be wrong about meanings, and occasionally most of us are wrong about a specialised meaning. |
| 7534 | In 1906, Russell decided that propositions did not, after all, exist [Russell, by Monk] |
| Full Idea: With a characteristic readiness to abandon views that he had previously considered definitively correct, Russell declared in 1906 that there were, after all, no such 'things' as propositions. It is judgements that are true or false. | |
| From: report of Bertrand Russell (On the Nature of Truth and Falsehood [1910]) by Ray Monk - Bertrand Russell: Spirit of Solitude Ch.6 | |
| A reaction: Written 1906. Russell developed a 'multiple relation theory of judgement'. But if a judgement is an assessment of truth or falsehood, what is it that is being assessed? |
| 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). |