74 ideas
16943 | Philosophy is continuous with science, and has no external vantage point [Quine] |
8721 | An 'impredicative' definition seems circular, because it uses the term being defined [Friend] |
8680 | Classical definitions attempt to refer, but intuitionist/constructivist definitions actually create objects [Friend] |
3678 | Reductio ad absurdum proves an idea by showing that its denial produces contradiction [Friend] |
8705 | Anti-realists see truth as our servant, and epistemically contrained [Friend] |
8713 | In classical/realist logic the connectives are defined by truth-tables [Friend] |
8708 | Double negation elimination is not valid in intuitionist logic [Friend] |
8694 | Free logic was developed for fictional or non-existent objects [Friend] |
8665 | A 'proper subset' of A contains only members of A, but not all of them [Friend] |
8672 | A 'powerset' is all the subsets of a set [Friend] |
8677 | Set theory makes a minimum ontological claim, that the empty set exists [Friend] |
8666 | Infinite sets correspond one-to-one with a subset [Friend] |
8682 | Major set theories differ in their axioms, and also over the additional axioms of choice and infinity [Friend] |
8709 | The law of excluded middle is syntactic; it just says A or not-A, not whether they are true or false [Friend] |
8711 | Intuitionists read the universal quantifier as "we have a procedure for checking every..." [Friend] |
8675 | Paradoxes can be solved by talking more loosely of 'classes' instead of 'sets' [Friend] |
8674 | The Burali-Forti paradox asks whether the set of all ordinals is itself an ordinal [Friend] |
16949 | Klein summarised geometry as grouped together by transformations [Quine] |
8667 | The 'integers' are the positive and negative natural numbers, plus zero [Friend] |
8668 | The 'rational' numbers are those representable as fractions [Friend] |
8670 | A number is 'irrational' if it cannot be represented as a fraction [Friend] |
8661 | The natural numbers are primitive, and the ordinals are up one level of abstraction [Friend] |
8664 | Cardinal numbers answer 'how many?', with the order being irrelevant [Friend] |
8671 | The 'real' numbers (rationals and irrationals combined) is the Continuum, which has no gaps [Friend] |
8663 | Raising omega to successive powers of omega reveal an infinity of infinities [Friend] |
8662 | The first limit ordinal is omega (greater, but without predecessor), and the second is twice-omega [Friend] |
8669 | Between any two rational numbers there is an infinite number of rational numbers [Friend] |
8676 | Is mathematics based on sets, types, categories, models or topology? [Friend] |
8678 | Most mathematical theories can be translated into the language of set theory [Friend] |
8701 | The number 8 in isolation from the other numbers is of no interest [Friend] |
8702 | In structuralism the number 8 is not quite the same in different structures, only equivalent [Friend] |
8699 | Are structures 'ante rem' (before reality), or are they 'in re' (grounded in physics)? [Friend] |
8696 | Structuralist says maths concerns concepts about base objects, not base objects themselves [Friend] |
8695 | Structuralism focuses on relations, predicates and functions, with objects being inessential [Friend] |
8700 | 'In re' structuralism says that the process of abstraction is pattern-spotting [Friend] |
8681 | The big problem for platonists is epistemic: how do we perceive, intuit, know or detect mathematical facts? [Friend] |
8712 | Mathematics should be treated as true whenever it is indispensable to our best physical theory [Friend] |
8716 | Formalism is unconstrained, so cannot indicate importance, or directions for research [Friend] |
8706 | Constructivism rejects too much mathematics [Friend] |
8707 | Intuitionists typically retain bivalence but reject the law of excluded middle [Friend] |
18680 | To avoid misunderstandings supervenience is often expressed negatively: no A-change without B-change [Orsi] |
16939 | Mass terms just concern spread, but other terms involve both spread and individuation [Quine] |
16948 | Once we know the mechanism of a disposition, we can eliminate 'similarity' [Quine] |
16945 | We judge things to be soluble if they are the same kind as, or similar to, things that do dissolve [Quine] |
8704 | Structuralists call a mathematical 'object' simply a 'place in a structure' [Friend] |
16944 | Science is common sense, with a sophisticated method [Quine] |
16941 | Induction relies on similar effects following from each cause [Quine] |
16940 | Induction is just more of the same: animal expectations [Quine] |
16933 | Grue is a puzzle because the notions of similarity and kind are dubious in science [Quine] |
16934 | General terms depend on similarities among things [Quine] |
16938 | To learn yellow by observation, must we be told to look at the colour? [Quine] |
8486 | Standards of similarity are innate, and the spacing of qualities such as colours can be mapped [Quine] |
16947 | Similarity is just interchangeability in the cosmic machine [Quine] |
8685 | Studying biology presumes the laws of chemistry, and it could never contradict them [Friend] |
8688 | Concepts can be presented extensionally (as objects) or intensionally (as a characterization) [Friend] |
16932 | Projectible predicates can be universalised about the kind to which they refer [Quine] |
18684 | Rather than requiring an action, a reason may 'entice' us, or be 'eligible', or 'justify' it [Orsi] |
18685 | Final value is favoured for its own sake, and personal value for someone's sake [Orsi] |
18666 | Value-maker concepts (such as courageous or elegant) simultaneously describe and evaluate [Orsi] |
18667 | The '-able' concepts (like enviable) say this thing deserves a particular response [Orsi] |
18679 | Things are only valuable if something makes it valuable, and we can ask for the reason [Orsi] |
18682 | A complex value is not just the sum of the values of the parts [Orsi] |
18683 | Trichotomy Thesis: comparable values must be better, worse or the same [Orsi] |
18686 | The Fitting Attitude view says values are fitting or reasonable, and values are just byproducts [Orsi] |
18672 | Values from reasons has the 'wrong kind of reason' problem - admiration arising from fear [Orsi] |
18677 | A thing may have final value, which is still derived from other values, or from relations [Orsi] |
18668 | Truths about value entail normative truths about actions or attitudes [Orsi] |
18670 | The Buck-Passing view of normative values says other properties are reasons for the value [Orsi] |
18669 | Values can be normative in the Fitting Attitude account, where 'good' means fitting favouring [Orsi] |
7375 | Quine probably regrets natural kinds now being treated as essences [Quine, by Dennett] |
16935 | If similarity has no degrees, kinds cannot be contained within one another [Quine] |
16936 | Comparative similarity allows the kind 'colored' to contain the kind 'red' [Quine] |
16937 | You can't base kinds just on resemblance, because chains of resemblance are a muddle [Quine] |
16942 | It is hard to see how regularities could be explained [Quine] |