83 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] |
| 15801 | Many philosophers aim to understand metaphysics by studying ourselves [Chisholm] |
| 13515 | To study abstract problems, some knowledge of set theory is essential [Hart,WD] |
| 15802 | I use variables to show that each item remains the same entity throughout [Chisholm] |
| 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] |
| 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] |
| 15832 | Events are states of affairs that occur at certain places and times [Chisholm] |
| 13488 | Mass words do not have plurals, or numerical adjectives, or use 'fewer' [Hart,WD] |
| 15809 | A state of affairs pertains to a thing if it implies that it has some property [Chisholm] |
| 15828 | I propose that events and propositions are two types of states of affairs [Chisholm] |
| 15829 | The mark of a state of affairs is that it is capable of being accepted [Chisholm] |
| 15830 | Some properties can never be had, like being a round square [Chisholm] |
| 15827 | Some properties, such as 'being a widow', can be seen as 'rooted outside the time they are had' [Chisholm] |
| 15804 | If some dogs are brown, that entails the properties of 'being brown' and 'being canine' [Chisholm] |
| 15810 | Maybe we can only individuate things by relating them to ourselves [Chisholm] |
| 15805 | Being the tallest man is an 'individual concept', but not a haecceity [Chisholm] |
| 15807 | A haecceity is a property had necessarily, and strictly confined to one entity [Chisholm] |
| 15814 | A peach is sweet and fuzzy, but it doesn't 'have' those qualities [Chisholm] |
| 12852 | If x is ever part of y, then y is necessarily such that x is part of y at any time that y exists [Chisholm, by Simons] |
| 15808 | A traditional individual essence includes all of a thing's necessary characteristics [Chisholm] |
| 12851 | Intermittence is seen in a toy fort, which is dismantled then rebuilt with the same bricks [Chisholm, by Simons] |
| 15806 | The property of being identical with me is an individual concept [Chisholm] |
| 15826 | There is 'loose' identity between things if their properties, or truths about them, might differ [Chisholm] |
| 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] |
| 15819 | Do sense-data have structure, location, weight, and constituting matter? [Chisholm] |
| 15816 | 'I feel depressed' is more like 'he runs slowly' than like 'he has a red book' [Chisholm] |
| 15817 | If we can say a man senses 'redly', why not also 'rectangularly'? [Chisholm] |
| 15818 | So called 'sense-data' are best seen as 'modifications' of the person experiencing them [Chisholm] |
| 411 | If we succeed in speaking the truth, we cannot know we have done it [Xenophanes] |
| 412 | If God had not created honey, men would say figs are sweeter [Xenophanes] |
| 15831 | Explanations have states of affairs as their objects [Chisholm] |
| 15811 | I am picked out uniquely by my individual essence, which is 'being identical with myself' [Chisholm] |
| 15815 | Sartre says the ego is 'opaque'; I prefer to say that it is 'transparent' [Chisholm] |
| 15813 | People use 'I' to refer to themselves, with the meaning of their own individual essence [Chisholm] |
| 15803 | Bad theories of the self see it as abstract, or as a bundle, or as a process [Chisholm] |
| 15821 | Determinism claims that every event has a sufficient causal pre-condition [Chisholm] |
| 13475 | The Fregean concept of GREEN is a function assigning true to green things, and false to the rest [Hart,WD] |
| 15824 | There are mere omissions (through ignorance, perhaps), and people can 'commit an omission' [Chisholm] |
| 15822 | The concept of physical necessity is basic to both causation, and to the concept of nature [Chisholm] |
| 1640 | The basic Eleatic belief was that all things are one [Xenophanes, by Plato] |
| 15823 | Some propose a distinct 'agent causation', as well as 'event causation' [Chisholm] |
| 15820 | A 'law of nature' is just something which is physically necessary [Chisholm] |
| 3055 | Xenophanes said the essence of God was spherical and utterly inhuman [Xenophanes, by Diog. Laertius] |
| 407 | Mortals believe gods are born, and have voices and clothes just like mortals [Xenophanes] |
| 408 | Ethiopian gods have black hair, and Thracian gods have red hair [Xenophanes] |