15 ideas
| 12452 | Our dislike of contradiction in logic is a matter of psychology, not mathematics [Brouwer] |
| Full Idea: Not to the mathematician, but to the psychologist, belongs the task of explaining why ...we are averse to so-called contradictory systems in which the negative as well as the positive of certain propositions are valid. | |
| From: Luitzen E.J. Brouwer (Intuitionism and Formalism [1912], p.79) | |
| A reaction: Was the turning point of Graham Priest's life the day he read this sentence? I don't agree. I take the principle of non-contradiction to be a highly generalised observation of how the world works (and Russell agrees with me). |
| 12451 | Scientific laws largely rest on the results of counting and measuring [Brouwer] |
| Full Idea: A large part of the natural laws introduced by science treat only of the mutual relations between the results of counting and measuring. | |
| From: Luitzen E.J. Brouwer (Intuitionism and Formalism [1912], p.77) | |
| A reaction: His point, I take it, is that the higher reaches of numbers have lost touch with the original point of the system. I now see the whole issue as just depending on conventions about the agreed extension of the word 'number'. |
| 12454 | Intuitionists only accept denumerable sets [Brouwer] |
| Full Idea: The intuitionist recognises only the existence of denumerable sets. | |
| From: Luitzen E.J. Brouwer (Intuitionism and Formalism [1912], p.80) | |
| A reaction: That takes you up to omega, but not beyond, presumably because it then loses sight of the original intuition of 'bare two-oneness' (Idea 12453). I sympathise, but the word 'number' has shifted its meaning a lot these days. |
| 12453 | Neo-intuitionism abstracts from the reuniting of moments, to intuit bare two-oneness [Brouwer] |
| Full Idea: Neo-intuitionism sees the falling apart of moments, reunited while remaining separated in time, as the fundamental phenomenon of human intellect, passing by abstracting to mathematical thinking, the intuition of bare two-oneness. | |
| From: Luitzen E.J. Brouwer (Intuitionism and Formalism [1912], p.80) | |
| A reaction: [compressed] A famous and somewhat obscure idea. He goes on to say that this creates one and two, and all the finite ordinals. |
| 23438 | Full rationality must include morality [Foot] |
| Full Idea: You haven't got a full idea of rationality until you've got morality within it. | |
| From: Philippa Foot (Interview with Philippa Foot [2003], p.35) | |
| A reaction: Does this mean that mathematical proofs are not rational, or that they are moral? |
| 10117 | Intuitonists in mathematics worried about unjustified assertion, as well as contradiction [Brouwer, by George/Velleman] |
| Full Idea: The concern of mathematical intuitionists was that the use of certain forms of inference generates, not contradiction, but unjustified assertions. | |
| From: report of Luitzen E.J. Brouwer (Intuitionism and Formalism [1912]) by A.George / D.J.Velleman - Philosophies of Mathematics Ch.6 | |
| A reaction: This seems to be the real origin of the verificationist idea in the theory of meaning. It is a hugely revolutionary idea - that ideas are not only ruled out of court by contradiction, but that there are other criteria which should also be met. |
| 23437 | Practical reason is goodness in choosing actions [Foot] |
| Full Idea: Practical rationality is goodness in respect of reason for actions, just as rationality of thinking is goodness in respect of beliefs. | |
| From: Philippa Foot (Interview with Philippa Foot [2003], p.35) | |
| A reaction: It is very Greek to think that rationality involves goodness. There seems to be a purely instrumental form of practical reason that just gets from A to B, as when giving accurate street directions to someone. |
| 23436 | It is an odd Humean view to think a reason to act must always involve caring [Foot] |
| Full Idea: One would need a very special, very Humean, view about reasons for actions to think a man doesn't have a reason unless he cares. | |
| From: Philippa Foot (Interview with Philippa Foot [2003], p.34-5) | |
| A reaction: She says she used to believe this, but was wrong. It is hard to imagine acting for reasons if they don't care about anything at all (even that it's their job). But then people just do care about things. |
| 23431 | Human defects are just like plant or animal defects [Foot] |
| Full Idea: We describe defects in human beings in the same way as we do defects in plants and animals. …You cannot talk about a river as being defective. | |
| From: Philippa Foot (Interview with Philippa Foot [2003], p.33) | |
| A reaction: This is a much clearer commitment to naturalistic ethics than I have found in her more academic writings. My opinion of Foot (which was already high) went up when I read this interview. …She says vice is a defect of the will. |
| 23433 | Humans need courage like a plant needs roots [Foot] |
| Full Idea: A plant needs strong roots in the same way human beings need courage. | |
| From: Philippa Foot (Interview with Philippa Foot [2003], p.33) | |
| A reaction: I'm not quite convince by the analogy, but I strongly agree with her basic approach. |
| 23432 | Concepts such as function, welfare, flourishing and interests only apply to living things [Foot] |
| Full Idea: There are concepts which apply only to living things, considered in their own right, which would include function, welfare, flourishing, interests and the good of something. | |
| From: Philippa Foot (Interview with Philippa Foot [2003], p.33) | |
| A reaction: This is a very Aristotelian view, with which I entirely agree. The central concept is function. |
| 23434 | There is no fact-value gap in 'owls should see in the dark' [Foot] |
| Full Idea: If you say 'an owl should be able to see in the dark' …you're not going to think that there's a gap between facts and evaluation. | |
| From: Philippa Foot (Interview with Philippa Foot [2003], p.33) | |
| A reaction: I take this to be a major and fundamental idea, which pinpoints the failure of Humeans to understand the world correctly. There is always total nihilism, of course, but that is a sort of blindness to how things are. Demanding 'proof' of values is crazy. |
| 23439 | Principles are not ultimate, but arise from the necessities of human life [Foot] |
| Full Idea: I don't believe in ultimate principles that must be simply affirmed or denied, but rather in an appeal to the necessities of human life. | |
| From: Philippa Foot (Interview with Philippa Foot [2003], p.37) | |
| A reaction: I agree. Humans have a strong tendency to elevate anything which they consider important into an absolute (such as the value of life, or freedom). |
| 23435 | If you demonstrate the reason to act, there is no further question of 'why should I?' [Foot] |
| Full Idea: You lose the sense of 'should' if you go on saying 'why should I?' when you've finished the argument about what is rational to do, what you've got reason to do. | |
| From: Philippa Foot (Interview with Philippa Foot [2003], P.34) | |
| A reaction: Some people reify the concept of duty, so that they do what is required without caring about the reason. I suppose that would wither if they were shown that no reason exists. |
| 15877 | The aim of science is just to create a comprehensive, elegant language to describe brute facts [Poincaré, by Harré] |
| Full Idea: In Poincaré's view, we try to construct a language within which the brute facts of experience are expressed as comprehensively and as elegantly as possible. The job of science is the forging of a language precisely suited to that purpose. | |
| From: report of Henri Poincaré (The Value of Science [1906], Pt III) by Rom Harré - Laws of Nature 2 | |
| A reaction: I'm often struck by how obscure and difficult our accounts of self-evident facts can be. Chairs are easy, and the metaphysics of chairs is hideous. Why is that? I'm a robust realist, but I like Poincaré's idea. He permits facts. |