42 ideas
1708 | In "Callias is just/not just/unjust", which of these are contraries? [Aristotle] |
21544 | It seems that when a proposition is false, something must fail to subsist [Russell] |
1703 | It is necessary that either a sea-fight occurs tomorrow or it doesn't, though neither option is in itself necessary [Aristotle] |
1704 | Statements are true according to how things actually are [Aristotle] |
22272 | Aristotle's later logic had to treat 'Socrates' as 'everything that is Socrates' [Potter on Aristotle] |
9405 | Square of Opposition: not both true, or not both false; one-way implication; opposite truth-values [Aristotle] |
9728 | Modal Square 1: □P and ¬◊¬P are 'contraries' of □¬P and ¬◊P [Aristotle, by Fitting/Mendelsohn] |
9729 | Modal Square 2: ¬□¬P and ◊P are 'subcontraries' of ¬□P and ◊¬P [Aristotle, by Fitting/Mendelsohn] |
9730 | Modal Square 3: □P and ¬◊¬P are 'contradictories' of ¬□P and ◊¬P [Aristotle, by Fitting/Mendelsohn] |
9731 | Modal Square 4: □¬P and ¬◊P are 'contradictories' of ¬□¬P and ◊P [Aristotle, by Fitting/Mendelsohn] |
9732 | Modal Square 5: □P and ¬◊¬P are 'subalternatives' of ¬□¬P and ◊P [Aristotle, by Fitting/Mendelsohn] |
9733 | Modal Square 6: □¬P and ¬◊P are 'subalternatives' of ¬□P and ◊¬P [Aristotle, by Fitting/Mendelsohn] |
10482 | The logic of ZF is classical first-order predicate logic with identity [Boolos] |
10492 | A few axioms of set theory 'force themselves on us', but most of them don't [Boolos] |
10485 | Naïve sets are inconsistent: there is no set for things that do not belong to themselves [Boolos] |
10484 | The iterative conception says sets are formed at stages; some are 'earlier', and must be formed first [Boolos] |
21593 | In talking of future sea-fights, Aristotle rejects bivalence [Aristotle, by Williamson] |
1701 | A prayer is a sentence which is neither true nor false [Aristotle] |
21539 | Excluded middle can be stated psychologically, as denial of p implies assertion of not-p [Russell] |
10491 | Infinite natural numbers is as obvious as infinite sentences in English [Boolos] |
10483 | Mathematics and science do not require very high orders of infinity [Boolos] |
10490 | Mathematics isn't surprising, given that we experience many objects as abstract [Boolos] |
1706 | Non-existent things aren't made to exist by thought, because their non-existence is part of the thought [Aristotle] |
1707 | Maybe necessity and non-necessity are the first principles of ontology [Aristotle] |
21538 | If two people perceive the same object, the object of perception can't be in the mind [Russell] |
21534 | The only thing we can say about relations is that they relate [Russell] |
21540 | Relational propositions seem to be 'about' their terms, rather than about the relation [Russell] |
10488 | It is lunacy to think we only see ink-marks, and not word-types [Boolos] |
10487 | I am a fan of abstract objects, and confident of their existence [Boolos] |
10489 | We deal with abstract objects all the time: software, poems, mistakes, triangles.. [Boolos] |
21536 | When I perceive a melody, I do not perceive the notes as existing [Russell] |
21535 | Objects only exist if they 'occupy' space and time [Russell] |
21533 | Contingency arises from tensed verbs changing the propositions to which they refer [Russell] |
21537 | I assume we perceive the actual objects, and not their 'presentations' [Russell] |
21532 | Full empiricism is not tenable, but empirical investigation is always essential [Russell] |
21542 | Do incorrect judgements have non-existent, or mental, or external objects? [Russell] |
21541 | The complexity of the content correlates with the complexity of the object [Russell] |
2337 | For Aristotle meaning and reference are linked to concepts [Aristotle, by Putnam] |
21543 | If p is false, then believing not-p is knowing a truth, so negative propositions must exist [Russell] |
13763 | Spoken sounds vary between people, but are signs of affections of soul, which are the same for all [Aristotle] |
1705 | It doesn't have to be the case that in opposed views one is true and the other false [Aristotle] |
1702 | Things may be necessary once they occur, but not be unconditionally necessary [Aristotle] |