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] |
| 15927 | Definition just needs negation, known variables, conjunction, disjunction, substitution and quantification [Weyl, by Lavine] |
| 8187 | Frege was strongly in favour of taking truth to attach to propositions [Frege, by Dummett] |
| 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] |
| 18772 | We can treat designation by a few words as a proper name [Frege] |
| 14075 | Proper name in modal contexts refer obliquely, to their usual sense [Frege, by Gibbard] |
| 10424 | A Fregean proper name has a sense determining an object, instead of a concept [Frege, by Sainsbury] |
| 18773 | People may have different senses for 'Aristotle', like 'pupil of Plato' or 'teacher of Alexander' [Frege] |
| 4978 | The meaning of a proper name is the designated object [Frege] |
| 10510 | Frege ascribes reference to incomplete expressions, as well as to singular terms [Frege, by Hale] |
| 18937 | If sentences have a 'sense', empty name sentences can be understood that way [Frege, by Sawyer] |
| 18940 | It is a weakness of natural languages to contain non-denoting names [Frege] |
| 18939 | In a logically perfect language every well-formed proper name designates an object [Frege] |
| 13506 | The universal quantifier can't really mean 'all', because there is no universal set [Hart,WD] |
| 9462 | Frege is intensionalist about reference, as it is determined by sense; identity of objects comes first [Frege, by Jacquette] |
| 18936 | Frege moved from extensional to intensional semantics when he added the idea of 'sense' [Frege, by Sawyer] |
| 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] |
| 10533 | We can't get a semantics from nouns and predicates referring to the same thing [Frege, by Dummett] |
| 4893 | Frege was asking how identities could be informative [Frege, by Perry] |
| 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] |
| 18752 | 'The concept "horse"' denotes a concept, yet seems also to denote an object [Frege, by McGee] |
| 13475 | The Fregean concept of GREEN is a function assigning true to green things, and false to the rest [Hart,WD] |
| 22318 | Frege failed to show when two sets of truth-conditions are equivalent [Frege, by Potter] |
| 4980 | The meaning (reference) of a sentence is its truth value - the circumstance of it being true or false [Frege] |
| 9180 | Holism says all language use is also a change in the rules of language [Frege, by Dummett] |
| 4981 | The reference of a word should be understood as part of the reference of the sentence [Frege] |
| 15597 | Frege's Puzzle: from different semantics we infer different reference for two names with the same reference [Frege, by Fine,K] |
| 17002 | Frege's 'sense' is ambiguous, between the meaning of a designator, and how it fixes reference [Kripke on Frege] |
| 18778 | Every descriptive name has a sense, but may not have a reference [Frege] |
| 7805 | Frege started as anti-realist, but the sense/reference distinction led him to realism [Frege, by Benardete,JA] |
| 4976 | The meaning (reference) of 'evening star' is the same as that of 'morning star', but not the sense [Frege] |
| 4977 | In maths, there are phrases with a clear sense, but no actual reference [Frege] |
| 4979 | We are driven from sense to reference by our desire for truth [Frege] |
| 15155 | Expressions always give ways of thinking of referents, rather than the referents themselves [Frege, by Soames] |
| 11126 | 'Sense' gives meaning to non-referring names, and to two expressions for one referent [Frege, by Margolis/Laurence] |
| 8164 | Frege was the first to construct a plausible theory of meaning [Frege, by Dummett] |
| 9817 | Earlier Frege focuses on content itself; later he became interested in understanding content [Frege, by Dummett] |
| 8171 | Frege divided the meaning of a sentence into sense, force and tone [Frege, by Dummett] |
| 4954 | Frege uses 'sense' to mean both a designator's meaning, and the way its reference is determined [Kripke on Frege] |
| 7304 | Frege explained meaning as sense, semantic value, reference, force and tone [Frege, by Miller,A] |