23 ideas
| 16477 | Asserting not-p is saying p is false [Russell] |
| Full Idea: When you do what a logician would call 'asserting not-p', you are saying 'p is false'. | |
| From: Bertrand Russell (An Inquiry into Meaning and Truth [1940], 5) | |
| A reaction: This is presumably classical logic. If we could label p as 'undetermined' (a third truth value), then 'not-p' might equally mean 'undetermined'. |
| 16484 | There are four experiences that lead us to talk of 'some' things [Russell] |
| Full Idea: Propositions about 'some' arise, in practice, in four ways: as generalisations of disjunctions; when an instance suggests compatibility of terms we thought incompatible; as steps to a generalisation; and in cases of imperfect memory. | |
| From: Bertrand Russell (An Inquiry into Meaning and Truth [1940], 5) | |
| A reaction: Modern logicians seem to have no interest in the question Russell is investigating here, but I love his attempt, however vague the result, to connect logic to real experience and thought. |
| 16486 | The physical world doesn't need logic, but the mental world does [Russell] |
| Full Idea: The non-mental world can be completely described without the use of any logical word, …but when it comes to the mental world, there are facts which cannot be mentioned without the use of logical words. | |
| From: Bertrand Russell (An Inquiry into Meaning and Truth [1940], 5) | |
| A reaction: He adds that logical words are not needed for physics, but are needed for psychology. I love Russell's interest in the psychology of logic (in defiance of the anti-psychologism of Frege). See also the ideas of Robert Hanna. |
| 2947 | Questions wouldn't lead anywhere without the law of excluded middle [Russell] |
| Full Idea: Without the law of excluded middle, we could not ask the questions that give rise to discoveries. | |
| From: Bertrand Russell (An Inquiry into Meaning and Truth [1940], c.p.88) |
| 16480 | A disjunction expresses indecision [Russell] |
| Full Idea: A disjunction is the verbal expression of indecision, or, if a question, of the desire to reach a decision. | |
| From: Bertrand Russell (An Inquiry into Meaning and Truth [1940], 5) | |
| A reaction: Russell is fishing here for Grice's conversational implicature. If you want to assert a simple proposition, you don't introduce it into an irrelevant disjunction, because that would have a particular expressive purpose. |
| 16479 | 'Or' expresses hesitation, in a dog at a crossroads, or birds risking grabbing crumbs [Russell] |
| Full Idea: Psychologically, 'or' corresponds to a state of hesitation. A dog waits at a fork in the road, to see which way you are going. For crumbs on a windowsill, birds behave in a manner we would express by 'shall I be brave, or go hungry?'. | |
| From: Bertrand Russell (An Inquiry into Meaning and Truth [1940], 5) | |
| A reaction: I love two facts here - first, that Russell wants to link the connective to the psychology of experience, and second, that a great logician wants to connect his logic to the minds of animals. |
| 16481 | 'Or' expresses a mental state, not something about the world [Russell] |
| Full Idea: When we assert 'p or q' we are in a state which is derivative from two previous states, and we express this state, not something about the world. | |
| From: Bertrand Russell (An Inquiry into Meaning and Truth [1940], 5) | |
| A reaction: His example: at a junction this road or that road goes to Oxford, but the world only contains the roads, not some state of 'this or that road'. He doesn't deny that in one sense 'p or q' tells you something about the world. |
| 16487 | Maybe the 'or' used to describe mental states is not the 'or' of logic [Russell] |
| Full Idea: It might be contended that, in describing what happens when a man believes 'p or q', the 'or' that we must use is not the same as the 'or' of logic. | |
| From: Bertrand Russell (An Inquiry into Meaning and Truth [1940], 5) | |
| A reaction: This seems to be the general verdict on Russell's enquiries in this chapter, but I love any attempt, however lacking in rigour etc., to connect formal logic to how we think, and thence to the world. |
| 16483 | Disjunction may also arise in practice if there is imperfect memory. [Russell] |
| Full Idea: Another situation in which a disjunction may arise is practice is imperfect memory. 'Either Brown or Jones told me that'. | |
| From: Bertrand Russell (An Inquiry into Meaning and Truth [1940], 5) |
| 16475 | A 'heterological' predicate can't be predicated of itself; so is 'heterological' heterological? Yes=no! [Russell] |
| Full Idea: A predicate is 'heterological' when it cannot be predicated of itself; thus 'long' is heterological because it is not a long word, but 'short' is homological. So is 'heterological' heterological? Either answer leads to a contradiction. | |
| From: Bertrand Russell (An Inquiry into Meaning and Truth [1940], 5) | |
| A reaction: [Grelling's Paradox] Yes: 'heterological' is heterological because it isn't heterological; No: it isn't, because it is. Russell says we therefore need a hierarchy of languages (types), and the word 'word' is outside the system. |
| 16482 | All our knowledge (if verbal) is general, because all sentences contain general words [Russell] |
| Full Idea: All our knowledge about the world, in so far as it is expressed in words, is more or less general, because every sentence contains at least one word that is not a proper name, and all such words are general. | |
| From: Bertrand Russell (An Inquiry into Meaning and Truth [1940], 5) | |
| A reaction: I really like this, especially because it addresses the excessive reliance of some essentialists on sortals, categories and natural kinds, instead of focusing on the actual physical essences of individual objects. |
| 4758 | Naïve realism leads to physics, but physics then shows that naïve realism is false [Russell] |
| Full Idea: Naïve realism leads to physics, and physics, if true, shows that naïve realism is false. Therefore naïve realism, if true, is false, therefore it is false. | |
| From: Bertrand Russell (An Inquiry into Meaning and Truth [1940], p.13) | |
| A reaction: I'm inclined to agree with this, though once you have gone off and explored representation and sense data you may be driven back to naïve realism again. |
| 16476 | For simple words, a single experience can show that they are true [Russell] |
| Full Idea: So long as a man avoids words which are condensed inductions (such as 'dog'), and confines himself to words that can describe a single experience, it is possible for a single experience to show that his words are true. | |
| From: Bertrand Russell (An Inquiry into Meaning and Truth [1940], 5) | |
| A reaction: One might question whether a line can be drawn between the inductive and the non-inductive in this way. I'm inclined just to say that the simpler the proposition the less room there is for error in confirming it. |
| 16485 | Perception can't prove universal generalisations, so abandon them, or abandon empiricism? [Russell] |
| Full Idea: Propositions about 'some' may be proved empirically, but propositions about 'all' are difficult to know, and can't be proved unless such propositions are in the premisses. These aren't in perception, so forgo general propositions, or abandon empiricism? | |
| From: Bertrand Russell (An Inquiry into Meaning and Truth [1940], 5) | |
| A reaction: This is obviously related to the difficulty empiricists have with induction. You could hardly persuade logicians to give up the universal quantifier, because it is needed in mathematics. Do we actually know any universal empirical truths? |
| 5662 | Maybe induction could never prove the existence of something unobservable [Ayer] |
| Full Idea: Some people hold that no inductive argument can give us any reason to believe in the existence of something which could not even in principle be observed. | |
| From: A.J. Ayer (The Concept of a Person [1963], §I) | |
| A reaction: I see nothing illogical in inferring the existence of a poltergeist from the recurrent flight of objects around my lounge. Only an excessive empiricism (which used to afflict Ayer) could lead to this claim. |
| 5664 | Consciousness must involve a subject, and only bodies identify subjects [Ayer] |
| Full Idea: It may not make sense to talk of states of consciousness except as the experiences of some conscious subject; and it may well be that this conscious subject can not be identified except by reference to his body. | |
| From: A.J. Ayer (The Concept of a Person [1963], §IV) | |
| A reaction: It strikes me that Ayer deserves more credit as a pioneer of this view. It tracks back to what may turn out to be the key difficulty for Descartes - how do you individuate a mental substance? I may identify me, but how do I identify you? |
| 5668 | People own conscious states because they are causally related to the identifying body [Ayer] |
| Full Idea: I think personal identity depends on the identity of the body, and that a person's ownership of states of consciousness consists in their standing in a special causal relation to the body by which he is identified. | |
| From: A.J. Ayer (The Concept of a Person [1963], §IV) | |
| A reaction: I think with this is right, with the slight reservation that Ayer talks as if there were two things which have a causal relationship, implying that the link is contingent. Better to think of the whole thing as a single causal network. |
| 5661 | We identify experiences by their owners, so we can't define owners by their experiences [Ayer] |
| Full Idea: Normally we identify experiences in terms of the persons whose experiences they are; but this will lead to a vicious circle if persons themselves are to be analysed in terms of their experiences. | |
| From: A.J. Ayer (The Concept of a Person [1963], §I) | |
| A reaction: This (from a leading empiricist) is a nice basic challenge to all empiricist accounts of personal identity. One might respond my saying that the circle is not vicious. There are two interlinked concepts (experience and persons), like day and night. |
| 5665 | Memory is the best proposal as what unites bundles of experiences [Ayer] |
| Full Idea: The most promising suggestion is that the bundles are tied together by means of memory. | |
| From: A.J. Ayer (The Concept of a Person [1963], §IV) | |
| A reaction: This is interesting for showing how Locke was essentially trying to meet (in advance) Hume's 'bundle' scepticism. Hume proposed associations as the unifying factor, instead of memories. Ayer proposes concepts as a candidate. |
| 5666 | Not all exerience can be remembered, as this would produce an infinite regress [Ayer] |
| Full Idea: Not every experience can be remembered; otherwise each piece of remembering, which is itself an experience, would have to be remembered, and each remembering of a remembering and so ad infinitum. | |
| From: A.J. Ayer (The Concept of a Person [1963], §IV) | |
| A reaction: See Idea 5667. Ayer takes for granted two sorts of consciousness - current awareness, and memory. Ayer brings out a nice difficulty for Locke's proposal, but also draws attention to what may be a very basic misunderstanding about the mind. |
| 5669 | Personal identity can't just be relations of experiences, because the body is needed to identify them [Ayer] |
| Full Idea: A Humean theory, in which a person's identity is made to depend upon relations between experiences ..is not tenable unless the experiences themselves can be identified, and that is only possible through their association with the body. | |
| From: A.J. Ayer (The Concept of a Person [1963], §IV) | |
| A reaction: This seems to me a very fruitful response to difficulties with the 'bundle' view of a person - a better response than the a priori claims of Butler and Reid, or the transcendental argument of Kant. Only a philosopher could ignore the body. |
| 16478 | A mother cat is paralysed if equidistant between two needy kittens [Russell] |
| Full Idea: I once, to test the story of Buridan's Ass, put a cat exactly half-way between her two kittens, both too young to move: for a time she found the disjunction paralysing. | |
| From: Bertrand Russell (An Inquiry into Meaning and Truth [1940], 5) | |
| A reaction: Buridan's Ass is said to have starved between two equal piles of hay. Reason can't be the tie-breaker; reason obviously says 'choose one!', but intellectualism demands a reason for the one you choose. |
| 5271 | Prejudice apart, push-pin has equal value with music and poetry [Bentham] |
| Full Idea: Prejudice apart, the game of push-pin is of equal value with the arts and science of music and poetry. | |
| From: Jeremy Bentham (Constitutional Code I [1827], p.139), quoted by J.R. Dinwiddy - Bentham p.114 | |
| A reaction: Mill quoted this with implied outrage, but Bentham was attacking public subsidies to the arts when he said it. It is a basic idea in the debate on pleasure - that pleasures are only distinguished by their intensity, not some other value. |