28 ideas
| 15118 | A successful Aristotelian 'definition' is what sciences produces after an investigation [Koslicki] |
| Full Idea: My current use of the Aristotelian term 'definition' is intended to correspond to what is typically accessible to a scientist only at the end of a successful investigation into the nature of a particular phenomenon. | |
| From: Kathrin Koslicki (Essence, Necessity and Explanation [2012], 13.3.1) | |
| A reaction: It is crucial to understand that Aristotle's definitions could be several hundred pages long. It has nothing to do with dictionary definitions. He proposes 'nominal' and 'real' definitions. |
| 15116 | Essences cause necessary features, and definitions describe those necessary features [Koslicki] |
| Full Idea: Since essences cause the other necessary features of a thing, so definitions, as the linguistic correlates of essences, explain, together with other axioms, the propositions describing those necessary features. | |
| From: Kathrin Koslicki (Essence, Necessity and Explanation [2012], 13.3.1) | |
| A reaction: This is nice and clear. Definitions are NOT essences - they are the linguistic correlates of essences, and mirror those essences. The necessary features are not the only things needing explanation. That picture is too passive. |
| 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. |
| 15110 | An essence and what merely follow from it are distinct [Koslicki] |
| Full Idea: We can distinguish (as Aristotle and Fine do) between what belongs to the essence of an object, and what merely follows from the essence of an object. | |
| From: Kathrin Koslicki (Essence, Necessity and Explanation [2012], 13.1) | |
| A reaction: This can help to clarify the confusions that result from treating necessary properties as if they were essential. |
| 15113 | Individuals are perceived, but demonstration and definition require universals [Koslicki] |
| Full Idea: Individual instances of a kind of phenomenon, in Aristotle's view, can only be perceived through sense-perception; but they are not the proper subject-matter of scientific demonstration and definition. | |
| From: Kathrin Koslicki (Essence, Necessity and Explanation [2012], 13.3.1) | |
| A reaction: A footnote (11) explains that this is because they involve syllogisms, which require universals. I take Aristotle, and anyone sensible, to rest on individual essences, but inevitably turn to generic essences when language becomes involved. |
| 15112 | If an object exists, then its essential properties are necessary [Koslicki] |
| Full Idea: If an object has a certain property essentially, then it follows that the object has the property necessarily (if it exists). | |
| From: Kathrin Koslicki (Essence, Necessity and Explanation [2012], 13.2) | |
| A reaction: She is citing Fine, who says that the converse (necessity implying essence) is false. I agree with that. I also willing to challenge the first bit. I suspect an object can retain identity and lose essence. Coma patient; broken clock; aged athlete. |
| 18969 | How do you distinguish three beliefs from four beliefs or two beliefs? [Quine] |
| Full Idea: Suppose I say that I have given up precisely three beliefs since lunch. An over-coarse individuation could reduce the number to two, and an over-fine one could raise it to four. | |
| From: Willard Quine (Propositional Objects [1965], p.144) | |
| A reaction: Obviously if you ask how many beliefs I hold, it would be crazy to give a precise answer. But if I search for my cat, I give up my belief that it is in the kitchen, in the lounge and in the bathroom. That's precise enough to be three beliefs, I think. |
| 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. |
| 15111 | In demonstration, the explanatory order must mirror the causal order of the phenomena [Koslicki] |
| Full Idea: Demonstration encompasses more than deductive entailment, in that the explanatory order of priority represented in a successful demonstration must mirror precisely the causal order of priority present in the phenomena in question. | |
| From: Kathrin Koslicki (Essence, Necessity and Explanation [2012], 13.1) | |
| A reaction: She is referring to Aristotle's 'Posterior Analytics'. Put so clearly this sounds like an incredibly useful concept in discussing how we present good modern scientific explanations. Reinstating Aristotle is a major priority for philosophy! |
| 15115 | In a demonstration the middle term explains, by being part of the definition [Koslicki] |
| Full Idea: In a proper demonstrative argument, the middle term must be explanatory of the conclusion, in a very specific sense: the middle term must state what properly belongs to the definition of the kind of phenomenon in question. | |
| From: Kathrin Koslicki (Essence, Necessity and Explanation [2012], 13.3.1) | |
| A reaction: So 'All men are mortal, S is a man, so S is mortal'. The middle term is 'man', which gives a generic explanation for why S is mortal. Explanation as categorisation? I don't think this is the whole story of Aristotelian explanation. |
| 15117 | Greek uses the same word for 'cause' and 'explanation' [Koslicki] |
| Full Idea: The Greek does not disambiguate between 'cause' and 'explanation', since the same terms ('aitia' and 'aition') can be translated in both ways. | |
| From: Kathrin Koslicki (Essence, Necessity and Explanation [2012], 13.3.1 n15) | |
| A reaction: This is essential information if we are to understand Aristotle's Four Causes, which are quite baffling if we take 'causes' in the modern way. The are the Four Modes of Explanation. |
| 15114 | Discovering the Aristotelian essence of thunder will tell us why thunder occurs [Koslicki] |
| Full Idea: Both the question 'what is thunder?', and the question 'why does thunder occur?', for Aristotle, are answered simultaneously, once it has been discovered what the essence of thunder it, i.e. what it is to be thunder. | |
| From: Kathrin Koslicki (Essence, Necessity and Explanation [2012], 13.3.1 n10) | |
| A reaction: I take this idea to be pretty much the whole story about essences. |
| 18967 | A 'proposition' is said to be the timeless cognitive part of the meaning of a sentence [Quine] |
| Full Idea: A 'proposition' is the meaning of a sentence. More precisely, since propositions are supposed to be true or false once and for all, it is the meaning of an eternal sentence. More precisely still, it is the 'cognitive' meaning, involving truth, not poetry. | |
| From: Willard Quine (Propositional Objects [1965], p.139) | |
| A reaction: Quine defines this in order to attack it. I equate a proposition with a thought, and take a sentence to be an attempt to express a proposition. I have no idea why they are supposed to be 'timeless'. Philosophers have some very odd ideas. |
| 18968 | The problem with propositions is their individuation. When do two sentences express one proposition? [Quine] |
| Full Idea: The trouble with propositions, as cognitive meanings of eternal sentences, is individuation. Given two eternal sentences, themselves visibly different linguistically, it is not sufficiently clear under when to say that they mean the same proposition. | |
| From: Willard Quine (Propositional Objects [1965], p.140) | |
| A reaction: If a group of people agree that two sentences mean the same thing, which happens all the time, I don't see what gives Quine the right to have a philosophical moan about some dubious activity called 'individuation'. |
| 18970 | The concept of a 'point' makes no sense without the idea of absolute position [Quine] |
| Full Idea: Unless we are prepared to believe that absolute position makes sense, the very idea of a point as an entity in its own right must be rejected as not merely mysterious but absurd. | |
| From: Willard Quine (Propositional Objects [1965], p.149) | |
| A reaction: The fact that without absolute position we can only think of 'points' as relative to a conceptual grid doesn't stop the grid from picking out actual locations in space, as shown by latitude and longitude. |