24 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). |
| 15941 | For intuitionists excluded middle is an outdated historical convention [Brouwer] |
| Full Idea: From the intuitionist standpoint the dogma of the universal validity of the principle of excluded third in mathematics can only be considered as a phenomenon of history of civilization, like the rationality of pi or rotation of the sky about the earth. | |
| From: Luitzen E.J. Brouwer (works [1930]), quoted by Shaughan Lavine - Understanding the Infinite VI.2 | |
| A reaction: [Brouwer 1952:510-11] |
| 18119 | Mathematics is a mental activity which does not use language [Brouwer, by Bostock] |
| Full Idea: Brouwer made the rather extraordinary claim that mathematics is a mental activity which uses no language. | |
| From: report of Luitzen E.J. Brouwer (Mathematics, Science and Language [1928]) by David Bostock - Philosophy of Mathematics 7.1 | |
| A reaction: Since I take language to have far less of a role in thought than is commonly believed, I don't think this idea is absurd. I would say that we don't use language much when we are talking! |
| 18247 | Brouwer saw reals as potential, not actual, and produced by a rule, or a choice [Brouwer, by Shapiro] |
| Full Idea: In his early writing, Brouwer took a real number to be a Cauchy sequence determined by a rule. Later he augmented rule-governed sequences with free-choice sequences, but even then the attitude is that Cauchy sequences are potential, not actual infinities. | |
| From: report of Luitzen E.J. Brouwer (works [1930]) by Stewart Shapiro - Philosophy of Mathematics 6.6 | |
| A reaction: This is the 'constructivist' view of numbers, as espoused by intuitionists like Brouwer. |
| 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'. |
| 18118 | Brouwer regards the application of mathematics to the world as somehow 'wicked' [Brouwer, by Bostock] |
| Full Idea: Brouwer regards as somehow 'wicked' the idea that mathematics can be applied to a non-mental subject matter, the physical world, and that it might develop in response to the needs which that application reveals. | |
| From: report of Luitzen E.J. Brouwer (Mathematics, Science and Language [1928]) by David Bostock - Philosophy of Mathematics 7.1 | |
| A reaction: The idea is that mathematics only concerns creations of the human mind. It presumably has no more application than, say, noughts-and-crosses. |
| 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. |
| 8728 | Intuitionist mathematics deduces by introspective construction, and rejects unknown truths [Brouwer] |
| Full Idea: Mathematics rigorously treated from the point of view of deducing theorems exclusively by means of introspective construction, is called intuitionistic mathematics. It deviates from classical mathematics, which believes in unknown truths. | |
| From: Luitzen E.J. Brouwer (Consciousness, Philosophy and Mathematics [1948]), quoted by Stewart Shapiro - Thinking About Mathematics 1.2 | |
| A reaction: Clearly intuitionist mathematics is a close cousin of logical positivism and the verification principle. This view would be anathema to Frege, because it is psychological. Personally I believe in the existence of unknown truths, big time! |
| 20653 | Six reduction levels: groups, lives, cells, molecules, atoms, particles [Putnam/Oppenheim, by Watson] |
| Full Idea: There are six 'reductive levels' in science: social groups, (multicellular) living things, cells, molecules, atoms, and elementary particles. | |
| From: report of H.Putnam/P.Oppenheim (Unity of Science as a Working Hypothesis [1958]) by Peter Watson - Convergence 10 'Intro' | |
| A reaction: I have the impression that fields are seen as more fundamental that elementary particles. What is the status of the 'laws' that are supposed to govern these things? What is the status of space and time within this picture? |
| 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. |
| 20712 | God is 'eternal' either by being non-temporal, or by enduring forever [Davies,B] |
| Full Idea: Saying 'God is eternal' means either that God is non-temporal or timeless, or that God has no beginning and no end. The first ('classical') view is found in Anselm, Augustine, Boethius, Aquinas, Calvin and Descartes. | |
| From: Brian Davies (Introduction to the Philosophy of Religion [1982], 8 'Meaning') | |
| A reaction: A God who is outside of time but performs actions is a bit of a puzzle. It seems that Augustine started the idea of a timeless God. |
| 20701 | Can God be good, if he has not maximised goodness? [Davies,B] |
| Full Idea: We may wonder whether God can be good since he has not produced more moral goodness than he has. We may wonder whether God is guilty by neglect. | |
| From: Brian Davies (Introduction to the Philosophy of Religion [1982], 3 'Freedom') | |
| A reaction: The orthodox response is that we cannot possibly know what the maximum of moral goodness would look like, so we can't make this judgement. Atheists say that God fails by human standards, which are not particularly high. |
| 20702 | The goodness of God may be a higher form than the goodness of moral agents [Davies,B] |
| Full Idea: If we can know that God exists and if God's goodness is not moral goodness, then moral goodness is not the highest form of goodness we know. There is the goodness of God to be reckoned with. | |
| From: Brian Davies (Introduction to the Philosophy of Religion [1982], 3 'Goodness') | |
| A reaction: This idea is to counter the charge that God fails to meet human standards for an ideal moral agent. But it sounds hand-wavy, since we presumably cannot comprehend the sort of goodness that is postulated here. |
| 20703 | How could God have obligations? What law could possibly impose them? [Davies,B] |
| Full Idea: We have good reason for resisting the suggestion that God has any duties or obligations. …What can oblige God in relation to his creatures? Could there be a law saying God has such obligations? Where does such a law come from? | |
| From: Brian Davies (Introduction to the Philosophy of Religion [1982], 3 'Goodness') | |
| A reaction: Plato can answer this question. Greek gods are not so supreme that nothing could put them under an obligation, but 'God' has to be supreme in every respect. |
| 20694 | 'Natural theology' aims to prove God to anyone (not just believers) by reason or argument [Davies,B] |
| Full Idea: 'Natural theology' is the attempt to show that belief in God's existence can be defended with reference to reason or argument which ought to be acceptable to anyone, not simply to those who believe in God's existence. | |
| From: Brian Davies (Introduction to the Philosophy of Religion [1982], 1 'Other') | |
| A reaction: I assume by 'reason or argument' he primarily means evidence (plus the ontological argument). He cites Karl Barth as objecting to the assumption of natural theology (preferring revelation). Presumably Kierkegaard offers a rival view too. |
| 20706 | A distinct cause of the universe can't be material (which would be part of the universe) [Davies,B] |
| Full Idea: If the universe was caused to come into being, it presumably could not have been caused to do so by anything material. For a material object would be part of the universe, and we are now asking for a cause distinct from the universe. | |
| From: Brian Davies (Introduction to the Philosophy of Religion [1982], 5 'God') | |
| A reaction: We're out of our depth here. We only have two modes of existence to offer, material and spiritual, and 'spiritual' means little more than non-material. |
| 20707 | The universe exhibits design either in its sense of purpose, or in its regularity [Davies,B] |
| Full Idea: The design argument offers two lines: the first states that the universe displays design in the sense of purpose; the second that it displays design in the sense of regularity. | |
| From: Brian Davies (Introduction to the Philosophy of Religion [1982], 6 'Versions') | |
| A reaction: I would have thought that you would infer the purpose from the regularity. How could you see purpose in a totally chaotic universe? |
| 20708 | If God is an orderly being, he cannot be the explanation of order [Davies,B] |
| Full Idea: If God is an instance of something orderly, how can he serve to account for the order of orderly things? | |
| From: Brian Davies (Introduction to the Philosophy of Religion [1982], 6 'b Has') | |
| A reaction: You can at least explain the tidiness of a house by the tidiness of its owner, but obviously that won't explain the phenomenon of tidiness. |
| 20710 | Maybe an abnormal state of mind is needed to experience God? [Davies,B] |
| Full Idea: Might it not be possible that experience of God requires an unusual state or psychological abnormality, just as an aerial view of Paris requires that one be in the unusual state of being abnormally elevated? | |
| From: Brian Davies (Introduction to the Philosophy of Religion [1982], 7 'Are the') | |
| A reaction: That would make sense if it were analogous to great mathematical or musical ability, but it sounds more like ouija boards in darkened rooms. Talent has a wonderful output, but people in mystical states don't return with proofs. |
| 20711 | A believer can experience the world as infused with God [Davies,B] |
| Full Idea: Maybe someone who believes in God can be regarded as experiencing everything as something behind which God lies. Believers see the world as a world in which God is present. | |
| From: Brian Davies (Introduction to the Philosophy of Religion [1982], 7 'Experiencing') | |
| A reaction: [Attributed to John Hick] This would count as supporting evidence for God, perhaps, if seeing reality as infused with God produces a consistent and plausible picture. But seeing reality as infused with other things might pass the same test. |
| 20709 | The experiences of God are inconsistent, not universal, and untestable [Davies,B] |
| Full Idea: A proclaimed experience of God must be rejected because a) there is no agreed test that it is such an experience, b) some people experience God's absence, and c) there is no uniformity of testimony about the experience. | |
| From: Brian Davies (Introduction to the Philosophy of Religion [1982], 7 'Objections') | |
| A reaction: [compressed] I'm not sure that absence of an experience is experience of an absence. Compare it with experiencing the greatness of Beethoven's Ninth. |
| 20697 | One does not need a full understanding of God in order to speak of God [Davies,B] |
| Full Idea: In order to speak meaningfully about God, it is not necessary that one should understand exactly the import of one's statements about him. | |
| From: Brian Davies (Introduction to the Philosophy of Religion [1982], 2 'Sayng') | |
| A reaction: Perfectly reasonable. To insist that all discussion of a thing requires exact understanding of the thing is ridiculous. Equally, though, to discuss God while denying all understanding of God is just as ridiculous. |
| 20699 | Paradise would not contain some virtues, such as courage [Davies,B] |
| Full Idea: There are virtues (such as courage) that would not be present in a paradise. | |
| From: Brian Davies (Introduction to the Philosophy of Religion [1982], 3 'Evil') | |
| A reaction: Part of a suggestion that morality would be entirely inapplicable in paradise, and so we need dangers etc in the world. |