42 ideas
| 23122 | Montaigne was the founding father of liberalism [Montaigne, by Gopnik] |
| Full Idea: The first liberal, the founding father if we have one, is the great sixteenth century French essayist Michel de Montaigne. | |
| From: report of Michel de Montaigne (On Cruelty [1580]) by Adam Gopnik - A Thousand Small Sanities 1 | |
| A reaction: He says this not on the basis of his politicies or achievements, but his general attitudes and values. It may be another hundred years before we can identify another obvious liberal (Locke?). |
| 125 | Is a gifted philosopher unmanly if he avoids the strife of the communal world? [Plato] |
| Full Idea: Callicles: Even a naturally gifted philosopher isn't going to develop into a real man, because he's avoiding the heart of his community and the thick of the agora. | |
| From: Plato (Gorgias [c.387 BCE], 485d) | |
| A reaction: A serious charge against philosophy. An attraction of the subject is its purity, its necessity, its timelessness, and in some ways these are just nicer and easier and more understandable than the hard mess of real life. But understanding has to be good. |
| 1654 | In "Gorgias" Socrates is confident that his 'elenchus' will decide moral truth [Vlastos on Plato] |
| Full Idea: In the 'Gorgias' Socrates is still supremely confident that the elenchus is the final arbiter of moral truth. | |
| From: comment on Plato (Gorgias [c.387 BCE]) by Gregory Vlastos - Socrates: Ironist and Moral Philosopher p.117 |
| 4321 | We should test one another, by asking and answering questions [Plato] |
| Full Idea: Test me, and let yourself be tested as well, by asking and answering questions. | |
| From: Plato (Gorgias [c.387 BCE], 462a) | |
| A reaction: The idea must be to avoid wild speculation, by continually filtering ideas through rival critical intelligences. The best philosophical method ever devised. |
| 8729 | Intuitionists deny excluded middle, because it is committed to transcendent truth or objects [Shapiro] |
| Full Idea: Intuitionists in mathematics deny excluded middle, because it is symptomatic of faith in the transcendent existence of mathematical objects and/or the truth of mathematical statements. | |
| From: Stewart Shapiro (Thinking About Mathematics [2000], 1.2) | |
| A reaction: There are other problems with excluded middle, such as vagueness, but on the whole I, as a card-carrying 'realist', am committed to the law of excluded middle. |
| 8763 | The number 3 is presumably identical as a natural, an integer, a rational, a real, and complex [Shapiro] |
| Full Idea: It is surely wise to identify the positions in the natural numbers structure with their counterparts in the integer, rational, real and complex number structures. | |
| From: Stewart Shapiro (Thinking About Mathematics [2000], 10.2) | |
| A reaction: The point is that this might be denied, since 3, 3/1, 3.00.., and -3*i^2 are all arrived at by different methods of construction. Natural 3 has a predecessor, but real 3 doesn't. I agree, intuitively, with Shapiro. Russell (1919) disagreed. |
| 18249 | Cauchy gave a formal definition of a converging sequence. [Shapiro] |
| Full Idea: A sequence a1,a2,... of rational numbers is 'Cauchy' if for each rational number ε>0 there is a natural number N such that for all natural numbers m, n, if m>N and n>N then -ε < am - an < ε. | |
| From: Stewart Shapiro (Thinking About Mathematics [2000], 7.2 n4) | |
| A reaction: The sequence is 'Cauchy' if N exists. |
| 8764 | Categories are the best foundation for mathematics [Shapiro] |
| Full Idea: There is a dedicated contingent who hold that the category of 'categories' is the proper foundation for mathematics. | |
| From: Stewart Shapiro (Thinking About Mathematics [2000], 10.3 n7) | |
| A reaction: He cites Lawvere (1966) and McLarty (1993), the latter presenting the view as a form of structuralism. I would say that the concept of a category will need further explication, and probably reduce to either sets or relations or properties. |
| 8762 | Two definitions of 3 in terms of sets disagree over whether 1 is a member of 3 [Shapiro] |
| Full Idea: Zermelo said that for each number n, its successor is the singleton of n, so 3 is {{{null}}}, and 1 is not a member of 3. Von Neumann said each number n is the set of numbers less than n, so 3 is {null,{null},{null,{null}}}, and 1 is a member of 3. | |
| From: Stewart Shapiro (Thinking About Mathematics [2000], 10.2) | |
| A reaction: See Idea 645 - Zermelo could save Plato from the criticisms of Aristotle! These two accounts are cited by opponents of the set-theoretical account of numbers, because it seems impossible to arbitrate between them. |
| 8760 | Numbers do not exist independently; the essence of a number is its relations to other numbers [Shapiro] |
| Full Idea: The structuralist vigorously rejects any sort of ontological independence among the natural numbers; the essence of a natural number is its relations to other natural numbers. | |
| From: Stewart Shapiro (Thinking About Mathematics [2000], 10.1) | |
| A reaction: This seems to place the emphasis on ordinals (what order?) rather than on cardinality (how many?). I am strongly inclined to think that this is the correct view, though you can't really have relations if there is nothing to relate. |
| 8761 | A 'system' is related objects; a 'pattern' or 'structure' abstracts the pure relations from them [Shapiro] |
| Full Idea: A 'system' is a collection of objects with certain relations among them; a 'pattern' or 'structure' is the abstract form of a system, highlighting the interrelationships and ignoring any features they do not affect how they relate to other objects. | |
| From: Stewart Shapiro (Thinking About Mathematics [2000], 10.1) | |
| A reaction: Note that 'ignoring' features is a psychological account of abstraction, which (thanks to Frege and Geach) is supposed to be taboo - but which I suspect is actually indispensable in any proper account of thought and concepts. |
| 8744 | Logicism seems to be a non-starter if (as is widely held) logic has no ontology of its own [Shapiro] |
| Full Idea: The thesis that principles of arithmetic are derivable from the laws of logic runs against a now common view that logic itself has no ontology. There are no particular logical objects. From this perspective logicism is a non-starter. | |
| From: Stewart Shapiro (Thinking About Mathematics [2000], 5.1) | |
| A reaction: This criticism strikes me as utterly devastating. There are two routes to go: prove that logic does have an ontology of objects (what would they be?), or - better - deny that arithmetic contains any 'objects'. Or give up logicism. |
| 8749 | Term Formalism says mathematics is just about symbols - but real numbers have no names [Shapiro] |
| Full Idea: Term Formalism is the view that mathematics is just about characters or symbols - the systems of numerals and other linguistic forms. ...This will cover integers and rational numbers, but what are real numbers supposed to be, if they lack names? | |
| From: Stewart Shapiro (Thinking About Mathematics [2000], 6.1.1) | |
| A reaction: Real numbers (such as pi and root-2) have infinite decimal expansions, so we can start naming those. We could also start giving names like 'Harry' to other reals, though it might take a while. OK, I give up. |
| 8750 | Game Formalism is just a matter of rules, like chess - but then why is it useful in science? [Shapiro] |
| Full Idea: Game Formalism likens mathematics to chess, where the 'content' of mathematics is exhausted by the rules of operating with its language. ...This, however, leaves the problem of why the mathematical games are so useful to the sciences. | |
| From: Stewart Shapiro (Thinking About Mathematics [2000], 6.1.2) | |
| A reaction: This thought pushes us towards structuralism. It could still be a game, but one we learned from observing nature, which plays its own games. Chess is, after all, modelled on warfare. |
| 8752 | Deductivism says mathematics is logical consequences of uninterpreted axioms [Shapiro] |
| Full Idea: The Deductivist version of formalism (sometimes called 'if-thenism') says that the practice of mathematics consists of determining logical consequences of otherwise uninterpreted axioms. | |
| From: Stewart Shapiro (Thinking About Mathematics [2000], 6.2) | |
| A reaction: [Hilbert is the source] More plausible than Term or Game Formalism (qv). It still leaves the question of why it seems applicable to nature, and why those particular axioms might be chosen. In some sense, though, it is obviously right. |
| 8753 | Critics resent the way intuitionism cripples mathematics, but it allows new important distinctions [Shapiro] |
| Full Idea: Critics commonly complain that the intuitionist restrictions cripple the mathematician. On the other hand, intuitionist mathematics allows for many potentially important distinctions not available in classical mathematics, and is often more subtle. | |
| From: Stewart Shapiro (Thinking About Mathematics [2000], 7.1) | |
| A reaction: The main way in which it cripples is its restriction on talk of infinity ('Cantor's heaven'), which was resented by Hilbert. Since high-level infinities are interesting, it would be odd if we were not allowed to discuss them. |
| 8731 | Conceptualist are just realists or idealist or nominalists, depending on their view of concepts [Shapiro] |
| Full Idea: I classify conceptualists according to what they say about properties or concepts. If someone classified properties as existing independent of language I would classify her as a realist in ontology of mathematics. Or they may be idealists or nominalists. | |
| From: Stewart Shapiro (Thinking About Mathematics [2000], 2.2.1) | |
| A reaction: In other words, Shapiro wants to eliminate 'conceptualist' as a useful label in philosophy of mathematics. He's probably right. All thought involves concepts, but that doesn't produce a conceptualist theory of, say, football. |
| 8730 | 'Impredicative' definitions refer to the thing being described [Shapiro] |
| Full Idea: A definition of a mathematical entity is 'impredicative' if it refers to a collection that contains the defined entity. The definition of 'least upper bound' is impredicative as it refers to upper bounds and characterizes a member of this set. | |
| From: Stewart Shapiro (Thinking About Mathematics [2000], 1.2) | |
| A reaction: The big question is whether mathematics can live with impredicative definitions, or whether they threaten to be viciously circular, and undermine the whole enterprise. |
| 8725 | Rationalism tries to apply mathematical methodology to all of knowledge [Shapiro] |
| Full Idea: Rationalism is a long-standing school that can be characterized as an attempt to extend the perceived methodology of mathematics to all of knowledge. | |
| From: Stewart Shapiro (Thinking About Mathematics [2000], 1.1) | |
| A reaction: Sometimes called 'Descartes's Dream', or the 'Enlightenment Project', the dream of proving everything. Within maths, Hilbert's Programme aimed for the same certainty. Idea 22 is the motto for the opposition to this approach. |
| 114 | Rhetoric can produce conviction, but not educate people about right and wrong [Plato] |
| Full Idea: Rhetoric is an agent of the kind of persuasion which is designed to produce conviction, but not to educate people about right and wrong. | |
| From: Plato (Gorgias [c.387 BCE], 455a) | |
| A reaction: Surely there must be good rhetoric (or at least it is an open question)? |
| 116 | Rhetoric is irrational about its means and its ends [Plato] |
| Full Idea: Rhetoric is a knack, because it lacks rational understanding of its object or what it dispenses (and can't explain the reason anything happens). | |
| From: Plato (Gorgias [c.387 BCE], 465a) | |
| A reaction: If there are cunning people who have the wrong sort of intelligence for morality, there must be cunning users of rhetoric who know exactly what they are doing. |
| 135 | All activity aims at the good [Plato] |
| Full Idea: All activity aims at the good. | |
| From: Plato (Gorgias [c.387 BCE], 499e) | |
| A reaction: He includes non-conscious activity, so this is the 'teleological' view of nature, which seems a bit optimistic to the modern mind. |
| 122 | Moral rules are made by the weak members of humanity [Plato] |
| Full Idea: Callicles: It's the weaklings who constitute the majority of the human race who make the rules. | |
| From: Plato (Gorgias [c.387 BCE], 483b) | |
| A reaction: An aristocrat bemoans democracy. Presumably the qualification for being a 'weakling' is shortage of money. How strong are the scions of the aristocrats? |
| 139 | A good person is bound to act well, and this brings happiness [Plato] |
| Full Idea: A good person is bound to do whatever he does well and successfully, and success brings fulfilment and happiness. | |
| From: Plato (Gorgias [c.387 BCE], 507c) | |
| A reaction: Not how we would see it, I guess, but this is the Greek idea that a good person is one who functions well. Anyone who functions well is probably having a good time. |
| 128 | Is it natural to simply indulge our selfish desires? [Plato] |
| Full Idea: Callicles: Nature says the only authentic way of life is to do nothing to hinder or restrain the expansion of one's desires. | |
| From: Plato (Gorgias [c.387 BCE], 491e) | |
| A reaction: Sounds like the natural desires of a young single man. Parents and spouses have natural desires that focus on other people's desires. |
| 4322 | In slaking our thirst the goodness of the action and the pleasure are clearly separate [Plato] |
| Full Idea: When we drink to quench thirst, we lose the distress of the thirst and the pleasure of drinking at the same moment, but one loss is good and the other bad, so the pleasure and the goodness must be separate. | |
| From: Plato (Gorgias [c.387 BCE], 497d) | |
| A reaction: This is open to the objection that the good of slaking one's thirst is a long-term pleasure, where the drinking is short-term, so pleasure is still the good. |
| 136 | Good should be the aim of pleasant activity, not the other way round [Plato] |
| Full Idea: Good should be the goal of pleasant activities, rather than pleasure being the goal of good activities. | |
| From: Plato (Gorgias [c.387 BCE], 500a) | |
| A reaction: Nice. Not far off what Aristotle says on the topic. So what activities should we seek out? Narrow the pleasures down to the good ones, or narrow the good ones down to the pleasurable? |
| 134 | Good and bad people seem to experience equal amounts of pleasure and pain [Plato] |
| Full Idea: There is little to tell between good and bad people (e.g. cowards) in terms of how much pleasure and distress they experience. | |
| From: Plato (Gorgias [c.387 BCE], 498c) | |
| A reaction: A very perceptive remark. If the good are people with empathy for others, then they may suffer more distress than the insensitive wicked. |
| 132 | If happiness is the satisfaction of desires, then a life of scratching itches should be happiness [Plato] |
| Full Idea: Socrates: I want to ask whether a lifetime spent scratching, itching and scratching, no end of scratching, is also a life of happiness. | |
| From: Plato (Gorgias [c.387 BCE], 494c) | |
| A reaction: There are plenty of people who think 'fun' is the main aim of life, and who fit what Socrates is referring to. We don't admire such a life, but not many people can be admired. |
| 4319 | In a fool's mind desire is like a leaky jar, insatiable in its desires, and order and contentment are better [Plato] |
| Full Idea: In a fool's mind desire is a leaky jar, …which is an analogy for the mind's insatiability, showing we should prefer an orderly life, in which one is content with whatever is to hand, to a self-indulgent life of insatiable desire. | |
| From: Plato (Gorgias [c.387 BCE], 493b) | |
| A reaction: This points to an interesting paradox, that pleasure requires the misery of desire. And yet absence of desire is like death. An Aristotelian mean, of living according to nature, seems the escape route. |
| 130 | Is the happiest state one of sensual, self-indulgent freedom? [Plato] |
| Full Idea: Callicles: If a person has the means to live a life of sensual, self-indulgent freedom, there's no better or happier state of existence. | |
| From: Plato (Gorgias [c.387 BCE], 492c) |
| 120 | Should we avoid evil because it will bring us bad consequences? [Plato] |
| Full Idea: Socrates: We should avoid doing wrong because of all the bad consequences it will bring us. | |
| From: Plato (Gorgias [c.387 BCE], 480a) |
| 118 | I would rather be a victim of crime than a criminal [Plato] |
| Full Idea: Socrates: If I had to choose between doing wrong and having wrong done to me, I'd prefer the latter to the former. | |
| From: Plato (Gorgias [c.387 BCE], 469c) | |
| A reaction: cf Democritus 68B45 |
| 140 | Self-indulgent desire makes friendship impossible, because it makes a person incapable of co-operation [Plato] |
| Full Idea: Self-indulgent desire makes a person incapable of co-operation, which is a prerequisite of friendship. | |
| From: Plato (Gorgias [c.387 BCE], 507e) |
| 131 | If absence of desire is happiness, then nothing is happier than a stone or a corpse [Plato] |
| Full Idea: Callicles: If people who need nothing are happy, there would be nothing happier than a stone or a corpse. | |
| From: Plato (Gorgias [c.387 BCE], 492e) | |
| A reaction: We aren't really supposed to approve of Callicles, but to me this is a splendidly crushing western response to many of the ideals found in eastern philosophy. |
| 119 | A criminal is worse off if he avoids punishment [Plato] |
| Full Idea: Socrates: A criminal is worse off if he doesn't pay the penalty, and continues to do wrong without getting punished. | |
| From: Plato (Gorgias [c.387 BCE], 472e) |
| 129 | Do most people praise self-discipline and justice because they are too timid to gain their own pleasure? [Plato] |
| Full Idea: Callicles: Why do most people praise self-discipline and justice? Because their own timidity makes them incapable of satisfying their pleasures. | |
| From: Plato (Gorgias [c.387 BCE], 492a) |
| 4320 | The popular view is that health is first, good looks second, and honest wealth third [Plato] |
| Full Idea: I'm sure you know the list of human advantages in the party song: 'The very best is health, Second good looks, and third honest wealth'. | |
| From: Plato (Gorgias [c.387 BCE], 451e) | |
| A reaction: This invites the obvious question of why anyone wants these three things, with the implied answer of 'pleasure'. But we might want them even if we couldn't use them, implying pluralism. |
| 137 | As with other things, a good state is organised and orderly [Plato] |
| Full Idea: As in every case (an artefact, a body, a mind, a creature), a good state is an organised and orderly state. | |
| From: Plato (Gorgias [c.387 BCE], 506e) |
| 141 | A good citizen won't be passive, but will redirect the needs of the state [Plato] |
| Full Idea: The only responsibility of a good member of a community is altering the community's needs rather than going along with them. | |
| From: Plato (Gorgias [c.387 BCE], 517b) |
| 123 | Do most people like equality because they are second-rate? [Plato] |
| Full Idea: Callicles: It's because most people are second-rate that they are happy for things to be distributed equally. | |
| From: Plato (Gorgias [c.387 BCE], 483c) |
| 124 | Does nature imply that it is right for better people to have greater benefits? [Plato] |
| Full Idea: Callicles: We only have to look at nature to find evidence that it is right for better to have a greater share than worse. | |
| From: Plato (Gorgias [c.387 BCE], 483d) |