18 ideas
| 13010 | In order to select the logic justified by experience, we would need to use a lot of logic [Boghossian on Quine] |
| Full Idea: Quine ends up with the logic that is maximally justified by experience, ...but a large number of the core principles of logic will have to be used to select the logic that is maximally justified by experience. | |
| From: comment on Willard Quine (Carnap and Logical Truth [1954]) by Paul Boghossian - Knowledge of Logic p.233 | |
| A reaction: In order to grasp some core principles of logic, you will probably need a certain amount of experience. I take logic to be an abstracted feature of reality (unless it is extended by pure fictions). Some basic logic may be hard wired in us. |
| 9002 | Elementary logic requires truth-functions, quantifiers (and variables), identity, and also sets of variables [Quine] |
| Full Idea: Elementary logic, as commonly systematized nowadays, comprises truth-function theory (involving 'or', 'and', 'not' etc.), quantifiers (and their variables), and identity theory ('='). In addition, set theory requires classes among values of variables. | |
| From: Willard Quine (Carnap and Logical Truth [1954], II) | |
| A reaction: Quine is famous for trying to squeeze properties out of the picture, which would then block higher-order logics (which quantify over properties). Quine's list gives a nice programme for a student of the philosophy of logic to understand. |
| 13681 | Logical consequence is marked by being preserved under all nonlogical substitutions [Quine, by Sider] |
| Full Idea: Quine's view of logical consequence is that it is when there is no way of uniformly substituting nonlogical expressions in the premises and consequences so that the premises all remain true but the consequence now becomes false. | |
| From: report of Willard Quine (Carnap and Logical Truth [1954], p.103) by Theodore Sider - Logic for Philosophy 1.5 | |
| A reaction: One might just say that the consequence holds if you insert consistent variables for the nonlogical terms, which looks like Aristotle's view of the matter. |
| 13829 | If logical truths essentially depend on logical constants, we had better define the latter [Hacking on Quine] |
| Full Idea: Quine said a logical truth is a truth in which only logical constants occur essentially, ...but then a fruitful definition of 'logical constant' is called for. | |
| From: comment on Willard Quine (Carnap and Logical Truth [1954]) by Ian Hacking - What is Logic? §02 |
| 9003 | Set theory was struggling with higher infinities, when new paradoxes made it baffling [Quine] |
| Full Idea: Unlike elementary logic, the truths of set theory are not obvious. Set theory was straining at the leash of intuition ever since Cantor discovered higher infinites; and with the added impetus of the paradoxes of set theory the leash snapped. | |
| From: Willard Quine (Carnap and Logical Truth [1954], II) | |
| A reaction: This problem seems to have forced Quine into platonism about sets, because he felt they were essential for mathematics and science, but couldn't be constructed with precision. So they must be real, but we don't quite understand them. |
| 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 |
| 9004 | If set theory is not actually a branch of logic, then Frege's derivation of arithmetic would not be from logic [Quine] |
| Full Idea: We might say that set theory is not really logic, but a branch of mathematics. This would deprive 'includes' of the status of a logical word. Frege's derivation of arithmetic would then cease to count as a derivation from logic: for he used set theory. | |
| From: Willard Quine (Carnap and Logical Truth [1954], II) | |
| A reaction: Quine has been making the point that higher infinities and the paradoxes undermine the status of set theory as logic, but he decides to continue thinking of set theory as logic. Critics of logicism frequently ask whether the reduction is to logic. |
| 6402 | In 1927, Russell analysed force and matter in terms of events [Russell, by Grayling] |
| Full Idea: In his 'Analysis of Matter' (1927), Russell sought to analyse the chief concepts of physics, such as force and matter, in terms of events. | |
| From: report of Bertrand Russell (The Analysis of Matter [1927]) by A.C. Grayling - Russell Ch.2 | |
| A reaction: My immediate reaction is that this is not very promising, simply because we can always ask why a particular event occurred, and this seems to point to a deeper level in the analysis. See Idea 4779, for example. |
| 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. |
| 9006 | Commitment to universals is as arbitrary or pragmatic as the adoption of a new system of bookkeeping [Quine] |
| Full Idea: One's hypothesis as to there being universals is at bottom just as arbitrary or pragmatic a matter as one's adoption of a new brand of set theory or even a new system of bookkeeping. | |
| From: Willard Quine (Carnap and Logical Truth [1954], x) | |
| A reaction: This spells out clearly the strongly pragmatist vein in Quine's thinking. |
| 14732 | A perceived physical object is events grouped around a centre [Russell] |
| Full Idea: The physical object, as inferred from perception, is a group of events arranged about a centre. | |
| From: Bertrand Russell (The Analysis of Matter [1927], 23) | |
| A reaction: At least I like the active aspect of this definition. You then have to explain what an event is, without mentioning objects. You'd better no mention properties either, since they will probably depend on the dreaded objects. |
| 14733 | An object produces the same percepts with or without a substance, so that is irrelevant to science [Russell] |
| Full Idea: There may be a substance at the centre of an object, but is no reason to think so, since the group of events making up the object will produce exactly the same percepts; so the substance, if there is one, is an abstract possibility irrelevant to science. | |
| From: Bertrand Russell (The Analysis of Matter [1927], 23) | |
| A reaction: All empiricists (as Russell is in this passage) seem to neglect inference to the best explanation. Things can be indirectly testable, and I would say that there are genuine general entities which are too close to abstraction to ever be testable. |
| 9001 | Frege moved Kant's question about a priori synthetic to 'how is logical certainty possible?' [Quine] |
| Full Idea: When Kant's arithmetical examples of a priori synthetic judgements were sweepingly disqualified by Frege's reduction of arithmetic to logic, attention moved to the less tendentious and logically prior question 'How is logical certainty possible?' | |
| From: Willard Quine (Carnap and Logical Truth [1954], I) | |
| A reaction: A nice summary of the story so far, from someone who should know. This still leaves the question open of whether any synthetic truths can be derived from the logical certainties which are available. |
| 6418 | Russell rejected phenomenalism because it couldn't account for causal relations [Russell, by Grayling] |
| Full Idea: Russell reverted to realism when he recognised that the notion of causality is problematic for phenomenalism; things in the world seem to affect one another causally in ways that are difficult to account for properly by mere reports of sense-experiences. | |
| From: report of Bertrand Russell (The Analysis of Matter [1927]) by A.C. Grayling - Russell Ch.3 | |
| A reaction: This is very interesting, and doesn't seem to have been enough to make A.J. Ayer eschew phenomenalism (Idea 5170). Once your metaphysics becomes realist (like Russell), your account of perception and objects has to change too. |
| 9005 | Examination of convention in the a priori begins to blur the distinction with empirical knowledge [Quine] |
| Full Idea: In trying to make sense of the role of convention in a priori knowledge, the very distinction between a priori and empirical begins to waver and dissolve. | |
| From: Willard Quine (Carnap and Logical Truth [1954], VI) | |
| A reaction: This is the next stage in the argument after Wittgenstein presents the apriori as nothing more than what arises from truth tables. The rationalists react by taking us back to the original 'natural light of reason' view. Then we go round again... |
| 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. |
| 21706 | At first matter is basic and known by sense-data; later Russell says matter is constructed [Russell, by Linsky,B] |
| Full Idea: In the beginning Russell's ontology included matter as basic, to be known, however, only by inference from sense-data. By the end he wanted to 'contruct' matter from sense-data. | |
| From: report of Bertrand Russell (The Analysis of Matter [1927]) by Bernard Linsky - Russell's Metaphysical Logic 1 | |
| A reaction: [see also p.133] Russell always seems to have been a robust realist about the external world, but the later view seems a lot less realist than the earlier view. |