79 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] |
| 22309 | An idea can only be like another idea [Berkeley] |
| 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] |
| 6717 | Abstract ideas are impossible [Berkeley] |
| 13488 | Mass words do not have plurals, or numerical adjectives, or use 'fewer' [Hart,WD] |
| 18876 | Berkeley does believe in trees, but is confused about what trees are [Berkeley, by Cameron] |
| 6715 | Universals do not have single meaning, but attach to many different particulars [Berkeley] |
| 6719 | No one will think of abstractions if they only have particular ideas [Berkeley] |
| 6714 | Universals do not have any intrinsic properties, but only relations to particulars [Berkeley] |
| 6729 | Material substance is just general existence which can have properties [Berkeley] |
| 16636 | A die has no distinct subject, but is merely a name for its modes or accidents [Berkeley] |
| 6722 | Perception is existence for my table, but also possible perception, by me or a spirit [Berkeley] |
| 6723 | The 'esse' of objects is 'percipi', and they can only exist in minds [Berkeley] |
| 6732 | When I shut my eyes, the things I saw may still exist, but in another mind [Berkeley] |
| 6724 | The only substance is spirit, or that which perceives [Berkeley] |
| 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] |
| 6726 | No one can, by abstraction, conceive extension and motion of bodies without sensible qualities [Berkeley] |
| 6728 | Motion is in the mind, since swifter ideas produce an appearance of slower motion [Berkeley] |
| 6727 | Figure and extension seem just as dependent on the observer as heat and cold [Berkeley] |
| 6495 | Berkeley's idealism resulted from fear of scepticism in representative realism [Robinson,H on Berkeley] |
| 6720 | Knowledge is of ideas from senses, or ideas of the mind, or operations on sensations [Berkeley] |
| 23636 | Berkeley's idealism gives no grounds for believing in other minds [Reid on Berkeley] |
| 6736 | I know other minds by ideas which are referred by me to other agents, as their effects [Berkeley] |
| 6713 | If animals have ideas, and are not machines, they must have some reason [Berkeley] |
| 6491 | Berkeley replaced intentionality with an anti-abstractionist imagist theory of thought [Berkeley, by Robinson,H] |
| 6711 | The mind creates abstract ideas by considering qualities separated from their objects [Berkeley] |
| 10581 | I can only combine particulars in imagination; I can't create 'abstract' ideas [Berkeley] |
| 6721 | Ideas are perceived by the mind, soul or self [Berkeley] |
| 13475 | The Fregean concept of GREEN is a function assigning true to green things, and false to the rest [Hart,WD] |
| 6716 | Language is presumably for communication, and names stand for ideas [Berkeley] |
| 6718 | I can't really go wrong if I stick to wordless thought [Berkeley] |
| 6731 | No one can explain how matter affects mind, so matter is redundant in philosophy [Berkeley] |
| 6730 | We discover natural behaviour by observing settled laws of nature, not necessary connections [Berkeley] |
| 15861 | The laws of nature are mental regularities which we learn by experience [Berkeley] |
| 6734 | If properties and qualities arise from an inward essence, we will remain ignorant of nature [Berkeley] |
| 4398 | An event causes another just if the second event would not have happened without the first [Lewis, by Psillos] |
| 6735 | All motion is relative, so a single body cannot move [Berkeley] |
| 6733 | I cannot imagine time apart from the flow of ideas in my mind [Berkeley] |
| 6737 | Particular evils are really good when linked to the whole system of beings [Berkeley] |