83 ideas
18996 | A statement S is 'partly true' if it has some wholly true parts [Yablo] |
19006 | An 'enthymeme' is an argument with an indispensable unstated assumption [Yablo] |
10987 | Three traditional names of rules are 'Simplification', 'Addition' and 'Disjunctive Syllogism' [Read] |
11004 | Necessity is provability in S4, and true in all worlds in S5 [Read] |
8859 | The main modal logics disagree over three key formulae [Yablo] |
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] |
11020 | Realisms like the full Comprehension Principle, that all good concepts determine sets [Read] |
18999 | y is only a proper part of x if there is a z which 'makes up the difference' between them [Yablo] |
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] |
19001 | 'Pegasus doesn't exist' is false without Pegasus, yet the absence of Pegasus is its truthmaker [Yablo] |
11007 | Quantifiers are second-order predicates [Read] |
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] |
9138 | An infinite series of sentences asserting falsehood produces the paradox without self-reference [Yablo, by Sorensen] |
8865 | If 'the number of Democrats is on the rise', does that mean that 50 million is on the rise? [Yablo] |
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] |
19002 | A nominalist can assert statements about mathematical objects, as being partly true [Yablo] |
8863 | We must treat numbers as existing in order to express ourselves about the arrangement of planets [Yablo] |
10580 | Mathematics is both necessary and a priori because it really consists of logical truths [Yablo] |
8862 | Platonic objects are really created as existential metaphors [Yablo] |
10579 | Putting numbers in quantifiable position (rather than many quantifiers) makes expression easier [Yablo] |
10578 | We are thought to know concreta a posteriori, and many abstracta a priori [Yablo] |
10577 | Concrete objects have few essential properties, but properties of abstractions are mostly essential [Yablo] |
19489 | For me, fictions are internally true, without a significant internal or external truth-value [Yablo] |
19490 | Make-believe can help us to reason about facts and scientific procedures [Yablo] |
19491 | 'The clouds are angry' can only mean '...if one were attributing emotions to clouds' [Yablo] |
8864 | We quantify over events, worlds, etc. in order to make logical possibilities clearer [Yablo] |
19494 | Fictionalism allows that simulated beliefs may be tracking real facts [Yablo] |
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] |
8858 | Philosophers keep finding unexpected objects, like models, worlds, functions, numbers, events, sets, properties [Yablo] |
10995 | A haecceity is a set of individual properties, essential to each thing [Read] |
14381 | A statue is essentially the statue, but its lump is not essentially a statue, so statue isn't lump [Yablo, by Rocca] |
18998 | Parthood lacks the restriction of kind which most relations have [Yablo] |
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] |
19493 | Governing possible worlds theory is the fiction that if something is possible, it happens in a world [Yablo] |
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] |
19004 | Gettier says you don't know if you are confused about how it is true [Yablo] |
19007 | A theory need not be true to be good; it should just be true about its physical aspects [Yablo] |
18993 | If sentences point to different evidence, they must have different subject-matter [Yablo] |
19003 | Most people say nonblack nonravens do confirm 'all ravens are black', but only a tiny bit [Yablo] |
10998 | The mind abstracts ways things might be, which are nonetheless real [Read] |
10805 | A sentence should be recarved to reveal its content or implication relations [Yablo] |
18992 | Sentence-meaning is the truth-conditions - plus factors responsible for them [Yablo] |
18994 | The content of an assertion can be quite different from compositional content [Yablo] |
11005 | Negative existentials with compositionality make the whole sentence meaningless [Read] |
18997 | Truth-conditions as subject-matter has problems of relevance, short cut, and reversal [Yablo] |
10966 | A proposition objectifies what a sentence says, as indicative, with secure references [Read] |
19005 | Not-A is too strong to just erase an improper assertion, because it actually reverses A [Yablo] |
8861 | Hardly a word in the language is devoid of metaphorical potential [Yablo] |
6005 | Animals are dangerous and nourishing, and can't form contracts of justice [Hermarchus, by Sedley] |