65 ideas
3656 | The greatest good for a state is true philosophers [Descartes] |
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] |
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] |
16744 | All powers can be explained by obvious features like size, shape and motion of matter [Descartes] |
5016 | Five universals: genus, species, difference, property, accident [Descartes] |
5015 | A universal is a single idea applied to individual things that are similar to one another [Descartes] |
8704 | Structuralists call a mathematical 'object' simply a 'place in a structure' [Friend] |
16630 | If we perceive an attribute, we infer the existence of some substance [Descartes] |
5013 | A substance needs nothing else in order to exist [Descartes] |
16633 | A substance has one principal property which is its nature and essence [Descartes] |
3658 | Total doubt can't include your existence while doubting [Descartes] |
5005 | I think, therefore I am, because for a thinking thing to not exist is a contradiction [Descartes] |
5006 | 'Thought' is all our conscious awareness, including feeling as well as understanding [Descartes] |
5012 | 'Nothing comes from nothing' is an eternal truth found within the mind [Descartes] |
5004 | We can know basic Principles without further knowledge, but not the other way round [Descartes] |
5014 | We can understand thinking occuring without imagination or sensation [Descartes] |
5017 | In thinking we shut ourselves off from other substances, showing our identity and separateness [Descartes] |
5010 | Our free will is so self-evident to us that it must be a basic innate idea [Descartes] |
5011 | There are two ultimate classes of existence: thinking substance and extended substance [Descartes] |
5018 | Even if tightly united, mind and body are different, as God could separate them [Descartes] |
8685 | Studying biology presumes the laws of chemistry, and it could never contradict them [Friend] |
5007 | Most errors of judgement result from an inaccurate perception of the facts [Descartes] |
8688 | Concepts can be presented extensionally (as objects) or intensionally (as a characterization) [Friend] |
5008 | The greatest perfection of man is to act by free will, and thus merit praise or blame [Descartes] |
5009 | We do not praise the acts of an efficient automaton, as their acts are necessary [Descartes] |
468 | Musical performance can reveal a range of virtues [Damon of Ath.] |
15987 | Physics only needs geometry or abstract mathematics, which can explain and demonstrate everything [Descartes] |
12730 | We will not try to understand natural or divine ends, or final causes [Descartes] |
16601 | Matter is not hard, heavy or coloured, but merely extended in space [Descartes] |