87 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] |
| 24084 | Seeing with other eyes is more egoism, but exploring other perspectives leads to objectivity [Nietzsche] |
| 24092 | I tell the truth, even if it is repulsive [Nietzsche] |
| 24114 | The pain in truth is when it destroys a belief [Nietzsche] |
| 24104 | We don't create logic, time and space! The mind obeys laws because they are true [Nietzsche] |
| 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] |
| 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] |
| 24112 | To think about being we must have an opinion about what it is [Nietzsche] |
| 13488 | Mass words do not have plurals, or numerical adjectives, or use 'fewer' [Hart,WD] |
| 24089 | Essences are fictions needed for beings who represent things [Nietzsche] |
| 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] |
| 24115 | There is no proof that we forget things - only that we can't recall [Nietzsche] |
| 24090 | Our inclinations would not conflict if we were a unity; we imagine unity for our multiplicity [Nietzsche] |
| 24099 | We contain many minds, which fight for the 'I' of the mind [Nietzsche] |
| 24102 | Thoughts are signs (just as words are) [Nietzsche] |
| 13475 | The Fregean concept of GREEN is a function assigning true to green things, and false to the rest [Hart,WD] |
| 24120 | Great orators lead their arguments, rather than following them [Nietzsche] |
| 24097 | The pragmatics of language is more comprehensible than the meaning [Nietzsche] |
| 24108 | Actions are just a release of force. They seize on something, which becomes the purpose [Nietzsche] |
| 24105 | Drives make us feel non-feelings; Will is the effect of those feelings [Nietzsche] |
| 24117 | We need lower and higher drives, but they must be under firm control [Nietzsche] |
| 24113 | Our motives don't explain our actions [Nietzsche] |
| 24087 | People who miss beauty seek the sublime, where even the ugly shows its 'beauty' [Nietzsche] |
| 24091 | The sublimity of nature which dwarfs us was a human creation [Nietzsche] |
| 24093 | We can aspire to greatness by creating new functions for ourselves [Nietzsche] |
| 24121 | Greeks might see modern analysis of what is human as impious [Nietzsche] |
| 24107 | Once a drive controls the intellect, it rules, and sets the goals [Nietzsche] |
| 24085 | For absolute morality a goal for mankind is needed [Nietzsche] |
| 24101 | We always assign values, but we may not value those values [Nietzsche] |
| 24094 | Humans are vividly aware of short-term effects, and almost ignorant of the long-term ones [Nietzsche] |
| 24111 | Happiness is the active equilibrium of our drives [Nietzsche] |
| 24109 | Actual morality is more complicated and subtle than theory (which gets paralysed) [Nietzsche] |
| 541 | Virtue comes more from habit than character [Critias] |
| 24110 | Some things we would never do, even for the highest ideals [Nietzsche] |
| 24103 | You should not want too many virtues; one is enough [Nietzsche] |
| 24106 | Talk of 'utility' presupposes that what is useful to people has been defined [Nietzsche] |
| 24086 | The goal is to settle human beings, like other animals, but humans are still changeable [Nietzsche] |
| 24123 | My eternal recurrence is opposed to feeling fragmented and imperfect [Nietzsche] |
| 24088 | See our present lives as eternal! Religions see it as fleeting, and aim at some different life [Nietzsche] |
| 24119 | The eternal return of wastefulness is a terrible thought [Nietzsche] |
| 24116 | Justice says people are not equal, and should become increasingly unequal [Nietzsche] |
| 24098 | Reasons that justify punishment can also justify the crime [Nietzsche] |
| 24118 | Do away with punishment. Counter-retribution is as bad as the crime [Nietzsche] |
| 24100 | If you don't want war, remove your borders; but you set up borders because you want war [Nietzsche] |
| 24095 | Our growth is too subtle to perceive, and long events are too slow for us to grasp [Nietzsche] |
| 24096 | Unlike time, space is subjective. Empty space was assumed, but it doesn't exist [Nietzsche] |
| 24122 | Life is forces conjoined by nutrition, to produce resistance, arrangement and value [Nietzsche] |
| 542 | Fear of the gods was invented to discourage secret sin [Critias] |