32 ideas
13838 | A decent modern definition should always imply a semantics [Hacking] |
13833 | 'Thinning' ('dilution') is the key difference between deduction (which allows it) and induction [Hacking] |
13834 | Gentzen's Cut Rule (or transitivity of deduction) is 'If A |- B and B |- C, then A |- C' [Hacking] |
13835 | Only Cut reduces complexity, so logic is constructive without it, and it can be dispensed with [Hacking] |
13845 | The various logics are abstractions made from terms like 'if...then' in English [Hacking] |
13840 | First-order logic is the strongest complete compact theory with Löwenheim-Skolem [Hacking] |
13844 | A limitation of first-order logic is that it cannot handle branching quantifiers [Hacking] |
13842 | Second-order completeness seems to need intensional entities and possible worlds [Hacking] |
8358 | There are no rules for the exact logic of ordinary language, because that doesn't exist [Strawson,P] |
13837 | With a pure notion of truth and consequence, the meanings of connectives are fixed syntactically [Hacking] |
13839 | Perhaps variables could be dispensed with, by arrows joining places in the scope of quantifiers [Hacking] |
6413 | 'The present King of France is bald' presupposes existence, rather than stating it [Strawson,P, by Grayling] |
8354 | Russell asks when 'The King of France is wise' would be a true assertion [Strawson,P] |
13843 | If it is a logic, the Löwenheim-Skolem theorem holds for it [Hacking] |
12132 | Indiscernibility is a necessary and sufficient condition for identity [Brody] |
15834 | Brody bases sortal essentialism on properties required throughout something's existence [Brody, by Mackie,P] |
12140 | Modern emphasis is on properties had essentially; traditional emphasis is on sort-defining properties [Brody] |
11895 | A sortal essence is a property which once possessed always possessed [Brody, by Mackie,P] |
12141 | Maybe essential properties are those which determine a natural kind? [Brody] |
12137 | De re essentialism standardly says all possible objects identical with a have a's essential properties [Brody] |
12142 | Essentially, a has P, always had P, must have had P, and has never had a future without P [Brody] |
12143 | An object having a property essentially is equivalent to its having it necessarily [Brody] |
12144 | Essentialism is justified if the essential properties of things explain their other properties [Brody] |
12139 | Mereological essentialism says that every part that ensures the existence is essential [Brody] |
12135 | Interrupted objects have two first moments of existence, which could be two beginnings [Brody] |
12130 | a and b share all properties; so they share being-identical-with-a; so a = b [Brody] |
12138 | Identity across possible worlds is prior to rigid designation [Brody] |
8356 | The meaning of an expression or sentence is general directions for its use, to refer or to assert [Strawson,P] |
10430 | Reference is mainly a social phenomenon [Strawson,P, by Sainsbury] |
10448 | If an expression can refer to anything, it may still instrinsically refer, but relative to a context [Bach on Strawson,P] |
8355 | Expressions don't refer; people use expressions to refer [Strawson,P] |
8357 | If an utterance fails to refer then it is a pseudo-use, though a speaker may think they assert something [Strawson,P] |