27 ideas
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. |
18086 | Weierstrass eliminated talk of infinitesimals [Weierstrass, by Kitcher] |
Full Idea: Weierstrass effectively eliminated the infinitesimalist language of his predecessors. | |
From: report of Karl Weierstrass (works [1855]) by Philip Kitcher - The Nature of Mathematical Knowledge 10.6 |
18092 | Weierstrass made limits central, but the existence of limits still needed to be proved [Weierstrass, by Bostock] |
Full Idea: After Weierstrass had stressed the importance of limits, one now needed to be able to prove the existence of such limits. | |
From: report of Karl Weierstrass (works [1855]) by David Bostock - Philosophy of Mathematics 4.4 | |
A reaction: The solution to this is found in work on series (going back to Cauchy), and on Dedekind's cuts. |
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. |
20086 | Nowadays sovereignty (once the basis of a state) has become relative [Reybrouck] |
Full Idea: In the twenty-first century, sovereignty, once the basis of the nation state, has become a relative concept. ...Powerlessness is the key word of our time. | |
From: David van Reybrouck (Against Elections [2013], 1 'Crisis') | |
A reaction: The point is that nation states now have limited power, in the face of larger unions, multinational companies, and global problems. |
20090 | Today it seems almost impossible to learn the will of the people [Reybrouck] |
Full Idea: Imagine having to develop a system today that would express the will of the people. | |
From: David van Reybrouck (Against Elections [2013], 2 'electoral') | |
A reaction: Our recent Brexit referendum didn't do the job, because it was confined to a single question. Van Reybrouck laughs at the idea of expressing it through a polling both. How about a council of 500, drawn by lots? Meet for three months. |
20087 | There are no united monolothic 'peoples', and no 'national gut feelings' [Reybrouck] |
Full Idea: There is no such thing as one monolithic 'people' (every society has its diversity), nor is there anything that could be described as a 'national gut feeling'. | |
From: David van Reybrouck (Against Elections [2013], 2 'populism') | |
A reaction: Rousseau yearned for a republic no bigger than Geneva. I don't see why we should give up on the general will in huge modern societies. It is likely, though, to be an anodyne lowest common denominator. No bad thing, perhaps. |
20089 | Technocrats may be efficient, but they lose legitimacy as soon as they do unpopular things [Reybrouck] |
Full Idea: Efficiency does not automatically generate legitimacy, and faith in the technocrat melts away as soon as spending cuts are implemented. | |
From: David van Reybrouck (Against Elections [2013], 2 'democracy') | |
A reaction: They can hang on to legitimacy if they can come up with some technical mumbo-jumbo like 'monetarism' which the people will swallow. |
20088 | Technocrats are expert managers, who replace politicians, and can be long-term and unpopular [Reybrouck] |
Full Idea: Technocracy is a system where experts are charged with looking after the public interest. ...Technocrats are managers who replace politicians, so they can concentrate on long-term solutions and announce unpopular measures. | |
From: David van Reybrouck (Against Elections [2013], 2 'technocracy') | |
A reaction: I like technocrats. They just need to be accountable. In the UK we have far more respect for the governor of the Bank of England than for any politician. |
20085 | Democracy is the best compromise between legitimacy and efficiency [Reybrouck] |
Full Idea: Democracy is the least bad form of all governments precisely because it attempts to find a healthy balance between legitimacy and efficiency. | |
From: David van Reybrouck (Against Elections [2013], 1 'Crisis') | |
A reaction: There seems to be a widespread feeling that democracy is declining in efficiency, and that may be because our remoteness from government decreases legitimacy, so we have less commitment to getting things done. |
20095 | A referendum result arises largely from ignorance [Reybrouck] |
Full Idea: In a referendum you ask everyone to vote on a subject that usually only a few know anything about. | |
From: David van Reybrouck (Against Elections [2013], 4 'remedies') | |
A reaction: Tell me about it! I was forced to vote in the 2016 Brexit referendum, and felt thoroughly out of my depth on such a complex economic question. |
20094 | You don't really govern people if you don't involve them [Reybrouck] |
Full Idea: Even with the best of intentions, those who govern the people without involving them, govern them only in a limited sense. | |
From: David van Reybrouck (Against Elections [2013], 4 intro) | |
A reaction: But if they are highly involved, who is governing who? Do we want the people to become happier about being governed, or do we want them more involved in doing the governing? |
20093 | In the 18th century democratic lots lost out to elections, that gave us a non-hereditary aristocracy [Reybrouck] |
Full Idea: The drawing of lots, the most democratic of all political instruments, lost out in the eighteenth century to elections, a procedure that was not invented as a democratic instrument, but as a means of bringing a new non-hereditary aristocracy to power. | |
From: David van Reybrouck (Against Elections [2013], 3 'democratisation') | |
A reaction: This is the basic thesis of Van Reybrouck's book. He argues for the extensive use of lots ('sortition') for getting people involved in modern democracies. I love the idea that in a good democracy you get an occasional chance to rule. |
20091 | Representative elections were developed in order to avoid democracy [Reybrouck] |
Full Idea: Bernard Manin (1995) revealed how, immediately after the American and French revolutions, the electoral-representative system was chosen with the intention of keeping at bay the tumult of democracy. | |
From: David van Reybrouck (Against Elections [2013], 3 'procedure') | |
A reaction: At the time America and France were two of the largest countries in the world, and communication and transport were slow. That has changed. |