77 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] |
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] |
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] |
13536 | Skolem did not believe in the existence of uncountable sets [Skolem] |
13481 | Maybe sets should be rethought in terms of the even more basic categories [Hart,WD] |
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] |
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] |
13471 | Mathematics makes existence claims, but philosophers usually say those are never analytic [Hart,WD] |
13488 | Mass words do not have plurals, or numerical adjectives, or use 'fewer' [Hart,WD] |
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] |
20589 | Maybe a person's true self is their second-order desires [Tuckness/Wolf] |
13475 | The Fregean concept of GREEN is a function assigning true to green things, and false to the rest [Hart,WD] |
20583 | If maximising pleasure needs measurement, so does fulfilling desires [Tuckness/Wolf] |
20584 | Desire satisfaction as the ideal is confused, because we desire what we judge to be good [Tuckness/Wolf] |
20598 | In a democracy, which 'people' are included in the decision process? [Tuckness/Wolf] |
20614 | People often have greater attachment to ethnic or tribal groups than to the state [Tuckness/Wolf] |
20596 | For global justice, adopt rules without knowing which country you will inhabit [Tuckness/Wolf] |
20593 | The veil of ignorance ensures both fairness and unanimity [Tuckness/Wolf] |
20608 | Unjust institutions may be seen as just; are they legitimate if just but seen as unjust? [Tuckness/Wolf] |
20597 | If winning elections depends on wealth, we have plutocracy instead of democracy [Tuckness/Wolf] |
20606 | Epistemic theories defend democracy as more likely to produce the right answer [Tuckness/Wolf] |
20600 | Which areas of public concern should be decided democratically, and which not? [Tuckness/Wolf] |
20609 | If several losing groups would win if they combine, a runoff seems called for [Tuckness/Wolf] |
20605 | Rights as interests (unlike rights as autonomy) supports mandatory voting [Tuckness/Wolf] |
20599 | How should democratic votes be aggregated? Can some person's votes count for more? [Tuckness/Wolf] |
20601 | Discussion before voting should be an essential part of democracy [Tuckness/Wolf] |
20613 | We have obligations to our family, even though we didn't choose its members [Tuckness/Wolf] |
20586 | Free speech does not include the right to shout 'Fire!' in a crowded theatre [Tuckness/Wolf] |
20587 | Most people want equality because they want a flourishing life [Tuckness/Wolf] |
20591 | If there is no suffering, wealth inequalities don't matter much [Tuckness/Wolf] |
20602 | Some rights are 'claims' that other people should act in a certain way [Tuckness/Wolf] |
20604 | Choice theory says protecting individual autonomy is basic (but needs to cover infants and animals) [Tuckness/Wolf] |
20603 | One theory (fairly utilitarian) says rights protect interests (but it needs to cover trivial interests) [Tuckness/Wolf] |
20607 | Having a right does not entail further rights needed to implement it [Tuckness/Wolf] |
20612 | If being subject to the law resembles a promise, we are morally obliged to obey it [Tuckness/Wolf] |
20611 | If others must obey laws that we like, we must obey laws that they like? [Tuckness/Wolf] |
20610 | Instead of against natural law, we might assess unjust laws against the values of the culture [Tuckness/Wolf] |
20617 | How should the punishment fit the crime (for stealing chickens?) [Tuckness/Wolf] |
20615 | Just wars: resist aggression, done on just cause, proportionate, last resort, not futile, legal [Tuckness/Wolf] |
20616 | During wars: proportional force, fair targets, fair weapons, safe prisoners, no reprisals [Tuckness/Wolf] |
20620 | If minority views are accepted in debate, then religious views must be accepted [Tuckness/Wolf] |
20619 | Is abortion the ending of a life, or a decision not to start one? [Tuckness/Wolf] |