86 ideas
13466 | We are all post-Kantians, because he set the current agenda for philosophy [Hart,WD] |
13477 | The problems are the monuments of philosophy [Hart,WD] |
13515 | To study abstract problems, some knowledge of set theory is essential [Hart,WD] |
9108 | From an impossibility anything follows [William of Ockham] |
16676 | Why use more things when fewer will do? [William of Ockham] |
6806 | Do not multiply entities beyond necessity [William of Ockham] |
9107 | A proposition is true if its subject and predicate stand for the same thing [William of Ockham] |
13469 | Tarski showed how we could have a correspondence theory of truth, without using 'facts' [Hart,WD] |
13504 | Truth for sentences is satisfaction of formulae; for sentences, either all sequences satisfy it (true) or none do [Hart,WD] |
13503 | A first-order language has an infinity of T-sentences, which cannot add up to a definition of truth [Hart,WD] |
16300 | Ockham had an early axiomatic account of truth [William of Ockham, by Halbach] |
13500 | Conditional Proof: infer a conditional, if the consequent can be deduced from the antecedent [Hart,WD] |
13502 | ∃y... is read as 'There exists an individual, call it y, such that...', and not 'There exists a y such that...' [Hart,WD] |
13456 | Set theory articulates the concept of order (through relations) [Hart,WD] |
13497 | Nowadays ZFC and NBG are the set theories; types are dead, and NF is only useful for the whole universe [Hart,WD] |
13443 | ∈ relates across layers, while ⊆ relates within layers [Hart,WD] |
13442 | Without the empty set we could not form a∩b without checking that a and b meet [Hart,WD] |
13493 | In the modern view, foundation is the heart of the way to do set theory [Hart,WD] |
13495 | Foundation Axiom: an nonempty set has a member disjoint from it [Hart,WD] |
13461 | We can choose from finite and evident sets, but not from infinite opaque ones [Hart,WD] |
13462 | With the Axiom of Choice every set can be well-ordered [Hart,WD] |
13516 | If we accept that V=L, it seems to settle all the open questions of set theory [Hart,WD] |
13441 | Naïve set theory has trouble with comprehension, the claim that every predicate has an extension [Hart,WD] |
13494 | The iterative conception may not be necessary, and may have fixed points or infinitely descending chains [Hart,WD] |
13457 | A 'partial ordering' is irreflexive and transitive; the sets are ordered, but not the subsets [Hart,WD] |
13458 | A partial ordering becomes 'total' if any two members of its field are comparable [Hart,WD] |
13460 | 'Well-ordering' must have a least member, so it does the natural numbers but not the integers [Hart,WD] |
13490 | Von Neumann defines α<β as α∈β [Hart,WD] |
13481 | Maybe sets should be rethought in terms of the even more basic categories [Hart,WD] |
9106 | The word 'every' only signifies when added to a term such as 'man', referring to all men [William of Ockham] |
13506 | The universal quantifier can't really mean 'all', because there is no universal set [Hart,WD] |
13512 | Modern model theory begins with the proof of Los's Conjecture in 1962 [Hart,WD] |
13505 | Model theory studies how set theory can model sets of sentences [Hart,WD] |
13511 | Model theory is mostly confined to first-order theories [Hart,WD] |
13513 | Models are ways the world might be from a first-order point of view [Hart,WD] |
13496 | First-order logic is 'compact': consequences of a set are consequences of a finite subset [Hart,WD] |
13484 | Berry's Paradox: we succeed in referring to a number, with a term which says we can't do that [Hart,WD] |
13482 | The Burali-Forti paradox is a crisis for Cantor's ordinals [Hart,WD] |
13507 | The machinery used to solve the Liar can be rejigged to produce a new Liar [Hart,WD] |
9117 | The smallest heap has four objects: three on the bottom, one on the top [Hart,WD, by Sorensen] |
13459 | The less-than relation < well-orders, and partially orders, and totally orders the ordinal numbers [Hart,WD] |
13491 | The axiom of infinity with separation gives a least limit ordinal ω [Hart,WD] |
13463 | There are at least as many infinite cardinals as transfinite ordinals (because they will map) [Hart,WD] |
13492 | Von Neumann's ordinals generalise into the transfinite better, because Zermelo's ω is a singleton [Hart,WD] |
13446 | 19th century arithmetization of analysis isolated the real numbers from geometry [Hart,WD] |
13509 | We can establish truths about infinite numbers by means of induction [Hart,WD] |
13474 | Euclid has a unique parallel, spherical geometry has none, and saddle geometry has several [Hart,WD] |
9113 | Just as unity is not a property of a single thing, so numbers are not properties of many things [William of Ockham] |
13471 | Mathematics makes existence claims, but philosophers usually say those are never analytic [Hart,WD] |
9110 | The words 'thing' and 'to be' assert the same idea, as a noun and as a verb [William of Ockham] |
16062 | A necessary relation between fact-levels seems to be a further irreducible fact [Lynch/Glasgow] |
16061 | If some facts 'logically supervene' on some others, they just redescribe them, adding nothing [Lynch/Glasgow] |
13488 | Mass words do not have plurals, or numerical adjectives, or use 'fewer' [Hart,WD] |
16060 | Nonreductive materialism says upper 'levels' depend on lower, but don't 'reduce' [Lynch/Glasgow] |
16064 | The hallmark of physicalism is that each causal power has a base causal power under it [Lynch/Glasgow] |
16608 | Ockham was an anti-realist about the categories [William of Ockham, by Pasnau] |
16654 | Our words and concepts don't always correspond to what is out there [William of Ockham] |
18529 | Relations are expressed either as absolute facts, or by a relational concept [William of Ockham] |
22132 | Species and genera are individual concepts which naturally signify many individuals [William of Ockham] |
9103 | A universal is not a real feature of objects, but only a thought-object in the mind [William of Ockham] |
15388 | Universals are single things, and only universal in what they signify [William of Ockham] |
16779 | Cut wood doesn't make a new substance, but seems to make separate subjects [William of Ockham] |
16757 | Hot water naturally cools down, which is due to the substantial form of the water [William of Ockham] |
16599 | Ockham says matter must be extended, so we don't need Quantity [William of Ockham, by Pasnau] |
16681 | Matter gets its quantity from condensation and rarefaction, which is just local motion [William of Ockham] |
9109 | If essence and existence were two things, one could exist without the other, which is impossible [William of Ockham] |
16792 | If parts change, the whole changes [William of Ockham] |
9089 | Knowledge is a quality existing subjectively in the soul [William of Ockham] |
9091 | Sometimes 'knowledge' just concerns the conclusion, sometimes the whole demonstration [William of Ockham] |
9100 | Our intellect only assents to what we believe to be true [William of Ockham] |
9090 | Knowledge is certain cognition of something that is true [William of Ockham] |
13480 | Fregean self-evidence is an intrinsic property of basic truths, rules and definitions [Hart,WD] |
13476 | The failure of key assumptions in geometry, mereology and set theory throw doubt on the a priori [Hart,WD] |
9101 | Abstractive cognition knows universals abstracted from many singulars [William of Ockham] |
9102 | If an animal approached from a distance, we might abstract 'animal' from one instance [William of Ockham] |
9114 | There are no secure foundations to prove the separate existence of mind, in reason or experience [William of Ockham] |
13475 | The Fregean concept of GREEN is a function assigning true to green things, and false to the rest [Hart,WD] |
9104 | A universal is the result of abstraction, which is only a kind of mental picturing [William of Ockham] |
9105 | Some concepts for propositions exist only in the mind, and in no language [William of Ockham] |
16675 | Every extended material substance is composed of parts distant from one another [William of Ockham] |
19381 | The past has ceased to exist, and the future does not yet exist, so time does not exist [William of Ockham] |
9111 | God is not wise, but more-than-wise; God is not good, but more-than-good [William of Ockham] |
8010 | William of Ockham is the main spokesman for God's commands being the source of morality [William of Ockham] |
9112 | We could never form a concept of God's wisdom if we couldn't abstract it from creatures [William of Ockham] |
9115 | To love God means to love whatever God wills to be loved [William of Ockham] |
16679 | Even an angel must have some location [William of Ockham, by Pasnau] |