82 ideas
9786 | Philosophers working like teams of scientists is absurd, yet isolation is hard [Cartwright,R] |
9784 | A false proposition isn't truer because it is part of a coherent system [Cartwright,R] |
13941 | Are the truth-bearers sentences, utterances, ideas, beliefs, judgements, propositions or statements? [Cartwright,R] |
13942 | Logicians take sentences to be truth-bearers for rigour, rather than for philosophical reasons [Cartwright,R] |
8472 | Sentential logic is consistent (no contradictions) and complete (entirely provable) [Orenstein] |
10987 | Three traditional names of rules are 'Simplification', 'Addition' and 'Disjunctive Syllogism' [Read] |
8476 | Axiomatization simply picks from among the true sentences a few to play a special role [Orenstein] |
11004 | Necessity is provability in S4, and true in all worlds in S5 [Read] |
8480 | S4: 'poss that poss that p' implies 'poss that p'; S5: 'poss that nec that p' implies 'nec that p' [Orenstein] |
11018 | There are fuzzy predicates (and sets), and fuzzy quantifiers and modifiers [Read] |
11011 | Same say there are positive, negative and neuter free logics [Read] |
8474 | Unlike elementary logic, set theory is not complete [Orenstein] |
11020 | Realisms like the full Comprehension Principle, that all good concepts determine sets [Read] |
8465 | Mereology has been exploited by some nominalists to achieve the effects of set theory [Orenstein] |
14187 | If logic is topic-neutral that means it delves into all subjects, rather than having a pure subject matter [Read] |
10986 | Not all validity is captured in first-order logic [Read] |
10972 | The non-emptiness of the domain is characteristic of classical logic [Read] |
11024 | Semantics must precede proof in higher-order logics, since they are incomplete [Read] |
10985 | We should exclude second-order logic, precisely because it captures arithmetic [Read] |
14188 | Not all arguments are valid because of form; validity is just true premises and false conclusion being impossible [Read] |
14182 | If the logic of 'taller of' rests just on meaning, then logic may be the study of merely formal consequence [Read] |
14183 | Maybe arguments are only valid when suppressed premises are all stated - but why? [Read] |
10970 | A theory of logical consequence is a conceptual analysis, and a set of validity techniques [Read] |
10984 | Logical consequence isn't just a matter of form; it depends on connections like round-square [Read] |
14184 | In modus ponens the 'if-then' premise contributes nothing if the conclusion follows anyway [Read] |
14186 | Logical connectives contain no information, but just record combination relations between facts [Read] |
10973 | A theory is logically closed, which means infinite premisses [Read] |
11007 | Quantifiers are second-order predicates [Read] |
8452 | Traditionally, universal sentences had existential import, but were later treated as conditional claims [Orenstein] |
8475 | The substitution view of quantification says a sentence is true when there is a substitution instance [Orenstein] |
10978 | In second-order logic the higher-order variables range over all the properties of the objects [Read] |
10971 | A logical truth is the conclusion of a valid inference with no premisses [Read] |
10988 | Any first-order theory of sets is inadequate [Read] |
10974 | Compactness is when any consequence of infinite propositions is the consequence of a finite subset [Read] |
10975 | Compactness does not deny that an inference can have infinitely many premisses [Read] |
10977 | Compactness blocks the proof of 'for every n, A(n)' (as the proof would be infinite) [Read] |
10976 | Compactness makes consequence manageable, but restricts expressive power [Read] |
11014 | Self-reference paradoxes seem to arise only when falsity is involved [Read] |
8454 | The whole numbers are 'natural'; 'rational' numbers include fractions; the 'reals' include root-2 etc. [Orenstein] |
11025 | Infinite cuts and successors seems to suggest an actual infinity there waiting for us [Read] |
10979 | Although second-order arithmetic is incomplete, it can fully model normal arithmetic [Read] |
10980 | Second-order arithmetic covers all properties, ensuring categoricity [Read] |
10997 | Von Neumann numbers are helpful, but don't correctly describe numbers [Read] |
8473 | The logicists held that is-a-member-of is a logical constant, making set theory part of logic [Orenstein] |
11016 | Would a language without vagueness be usable at all? [Read] |
11019 | Supervaluations say there is a cut-off somewhere, but at no particular place [Read] |
11012 | A 'supervaluation' gives a proposition consistent truth-value for classical assignments [Read] |
11013 | Identities and the Indiscernibility of Identicals don't work with supervaluations [Read] |
8458 | Just individuals in Nominalism; add sets for Extensionalism; add properties, concepts etc for Intensionalism [Orenstein] |
9783 | While no two classes coincide in membership, there are distinct but coextensive attributes [Cartwright,R] |
10995 | A haecceity is a set of individual properties, essential to each thing [Read] |
14961 | Clearly a pipe can survive being taken apart [Cartwright,R] |
14962 | Bodies don't becomes scattered by losing small or minor parts [Cartwright,R] |
13952 | Essentialism says some of a thing's properties are necessary, and could not be absent [Cartwright,R] |
13954 | The difficulty in essentialism is deciding the grounds for rating an attribute as essential [Cartwright,R] |
13955 | Essentialism is said to be unintelligible, because relative, if necessary truths are all analytic [Cartwright,R] |
13953 | An act of ostension doesn't seem to need a 'sort' of thing, even of a very broad kind [Cartwright,R] |
13945 | A token isn't a unique occurrence, as the case of a word or a number shows [Cartwright,R] |
11001 | Equating necessity with truth in every possible world is the S5 conception of necessity [Read] |
10992 | The point of conditionals is to show that one will accept modus ponens [Read] |
10989 | The standard view of conditionals is that they are truth-functional [Read] |
11017 | Some people even claim that conditionals do not express propositions [Read] |
14185 | Conditionals are just a shorthand for some proof, leaving out the details [Read] |
10983 | Knowledge of possible worlds is not causal, but is an ontology entailed by semantics [Read] |
10982 | How can modal Platonists know the truth of a modal proposition? [Read] |
10996 | Actualism is reductionist (to parts of actuality), or moderate realist (accepting real abstractions) [Read] |
10981 | A possible world is a determination of the truth-values of all propositions of a domain [Read] |
11000 | If worlds are concrete, objects can't be present in more than one, and can only have counterparts [Read] |
8457 | The Principle of Conservatism says we should violate the minimum number of background beliefs [Orenstein] |
10998 | The mind abstracts ways things might be, which are nonetheless real [Read] |
13948 | For any statement, there is no one meaning which any sentence asserting it must have [Cartwright,R] |
13950 | People don't assert the meaning of the words they utter [Cartwright,R] |
8477 | People presume meanings exist because they confuse meaning and reference [Orenstein] |
8471 | Three ways for 'Socrates is human' to be true are nominalist, platonist, or Montague's way [Orenstein] |
11005 | Negative existentials with compositionality make the whole sentence meaningless [Read] |
13944 | We can pull apart assertion from utterance, and the action, the event and the subject-matter for each [Cartwright,R] |
13947 | 'It's raining' makes a different assertion on different occasions, but its meaning remains the same [Cartwright,R] |
10966 | A proposition objectifies what a sentence says, as indicative, with secure references [Read] |
13943 | We can attribute 'true' and 'false' to whatever it was that was said [Cartwright,R] |
13946 | To assert that p, it is neither necessary nor sufficient to utter some particular words [Cartwright,R] |
8484 | If two people believe the same proposition, this implies the existence of propositions [Orenstein] |
13951 | Assertions, unlike sentence meanings, can be accurate, probable, exaggerated, false.... [Cartwright,R] |