96 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] |
| 15447 | We shouldn't always follow where the argument leads! [Lewis on Plato] |
| 13515 | To study abstract problems, some knowledge of set theory is essential [Hart,WD] |
| 243 | It is foolish to quarrel with the mind's own reasoning processes [Plato] |
| 241 | We ought to follow where the argument leads us [Plato] |
| 21264 | Mortals are incapable of being fully rational [Plato] |
| 251 | Truth has the supreme value, for both gods and men [Plato] |
| 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] |
| 13462 | With the Axiom of Choice every set can be well-ordered [Hart,WD] |
| 13461 | We can choose from finite and evident sets, but not from infinite opaque ones [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] |
| 13460 | 'Well-ordering' must have a least member, so it does the natural numbers but not the integers [Hart,WD] |
| 13458 | A partial ordering becomes 'total' if any two members of its field are comparable [Hart,WD] |
| 13457 | A 'partial ordering' is irreflexive and transitive; the sets are ordered, but not the subsets [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] |
| 17505 | Using proper names properly doesn't involve necessary and sufficient conditions [Putnam] |
| 13506 | The universal quantifier can't really mean 'all', because there is no universal set [Hart,WD] |
| 13513 | Models are ways the world might be from a first-order point of view [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] |
| 13512 | Modern model theory begins with the proof of Los's Conjecture in 1962 [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] |
| 13463 | There are at least as many infinite cardinals as transfinite ordinals (because they will map) [Hart,WD] |
| 13491 | The axiom of infinity with separation gives a least limit ordinal ω [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] |
| 21259 | To grasp a thing we need its name, its definition, and what it really is [Plato] |
| 11908 | Putnam bases essences on 'same kind', but same kinds may not share properties [Mackie,P on Putnam] |
| 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] |
| 17508 | Science aims at truth, not at 'simplicity' [Putnam] |
| 21260 | Soul is what is defined by 'self-generating motion' [Plato] |
| 276 | My individuality is my soul, which carries my body around [Plato] |
| 13475 | The Fregean concept of GREEN is a function assigning true to green things, and false to the rest [Hart,WD] |
| 17506 | I now think reference by the tests of experts is a special case of being causally connected [Putnam] |
| 249 | People who value beauty above virtue insult the soul by placing the body above it [Plato] |
| 265 | An action is only just if it is performed by someone with a just character and outlook [Plato] |
| 269 | Attempted murder is like real murder, but we should respect the luck which avoided total ruin [Plato] |
| 240 | It would be strange if the gods rewarded those who experienced the most pleasure in life [Plato] |
| 264 | The conquest of pleasure is the noblest victory of all [Plato] |
| 253 | Every crime is the result of excessive self-love [Plato] |
| 4332 | Virtue is a concord of reason and emotion, with pleasure and pain trained to correct ends [Plato] |
| 248 | A serious desire for moral excellence is very rare indeed [Plato] |
| 263 | The only worthwhile life is one devoted to physical and moral perfection [Plato] |
| 235 | Virtue is the aim of all laws [Plato] |
| 277 | The Guardians must aim to discover the common element in the four cardinal virtues [Plato] |
| 254 | Excessive laughter and tears must be avoided [Plato] |
| 266 | Injustice is the mastery of the soul by bad feelings, even if they do not lead to harm [Plato] |
| 256 | Virtue and great wealth are incompatible [Plato] |
| 242 | The best people are produced where there is no excess of wealth or poverty [Plato] |
| 245 | Totalitarian states destroy friendships and community spirit [Plato] |
| 239 | Education in virtue produces citizens who are active but obedient [Plato] |
| 262 | Men and women should qualify equally for honours on merit [Plato] |
| 1402 | Friendship is impossible between master and slave, even if they are made equal [Plato] |
| 236 | Sound laws achieve the happiness of those who observe them [Plato] |
| 259 | Justice is granting the equality which unequals deserve [Plato] |
| 257 | Mathematics has the widest application of any subject on the curriculum [Plato] |
| 238 | Children's games should channel their pleasures into adult activity [Plato] |
| 260 | Control of education is the key office of state, and should go to the best citizen [Plato] |
| 4331 | Education is channelling a child's feelings into the right course before it understands why [Plato] |
| 250 | The best way to educate the young is not to rebuke them, but to set a good example [Plato] |
| 275 | Creation is not for you; you exist for the sake of creation [Plato] |
| 17507 | Natural kind stereotypes are 'strong' (obvious, like tiger) or 'weak' (obscure, like molybdenum) [Putnam] |
| 11904 | Express natural kinds as a posteriori predicate connections, not as singular terms [Putnam, by Mackie,P] |
| 273 | Movement is transmitted through everything, and it must have started with self-generated motion [Plato] |
| 8004 | In 'The Laws', to obey the law is to be obey god [Plato, by MacIntyre] |
| 21257 | Self-generating motion is clearly superior to all other kinds of motion [Plato] |
| 21258 | The only possible beginning for the endless motions of reality is something self-generated [Plato] |
| 21261 | Self-moving soul has to be the oldest thing there is [Plato] |
| 274 | Soul must be the cause of all the opposites, such as good and evil or beauty and ugliness [Plato] |
| 21263 | If all the motions of nature reflect calculations of reason, then the best kind of soul must direct it [Plato] |
| 278 | If astronomical movements are seen as necessary instead of by divine will, this leads to atheism [Plato] |
| 21265 | The heavens must be full of gods, controlling nature either externally or from within [Plato] |
| 21262 | There must be at least two souls controlling the cosmos, one doing good, the other the opposite [Plato] |