39 ideas
13252 | Some truths have true negations [Beall/Restall] |
16477 | Asserting not-p is saying p is false [Russell] |
13247 | A truthmaker is an object which entails a sentence [Beall/Restall] |
16484 | There are four experiences that lead us to talk of 'some' things [Russell] |
13249 | (∀x)(A v B) |- (∀x)A v (∃x)B) is valid in classical logic but invalid intuitionistically [Beall/Restall] |
13243 | Excluded middle must be true for some situation, not for all situations [Beall/Restall] |
13242 | It's 'relevantly' valid if all those situations make it true [Beall/Restall] |
13246 | Relevant logic does not abandon classical logic [Beall/Restall] |
13245 | Relevant consequence says invalidity is the conclusion not being 'in' the premises [Beall/Restall] |
13254 | A doesn't imply A - that would be circular [Beall/Restall] |
13255 | Relevant logic may reject transitivity [Beall/Restall] |
13250 | Free logic terms aren't existential; classical is non-empty, with referring names [Beall/Restall] |
13235 | Logic studies consequence; logical truths are consequences of everything, or nothing [Beall/Restall] |
13238 | Syllogisms are only logic when they use variables, and not concrete terms [Beall/Restall] |
13234 | The view of logic as knowing a body of truths looks out-of-date [Beall/Restall] |
16486 | The physical world doesn't need logic, but the mental world does [Russell] |
13232 | Logic studies arguments, not formal languages; this involves interpretations [Beall/Restall] |
13241 | The model theory of classical predicate logic is mathematics [Beall/Restall] |
13253 | There are several different consequence relations [Beall/Restall] |
13240 | A sentence follows from others if they always model it [Beall/Restall] |
2947 | Questions wouldn't lead anywhere without the law of excluded middle [Russell] |
16480 | A disjunction expresses indecision [Russell] |
16479 | 'Or' expresses hesitation, in a dog at a crossroads, or birds risking grabbing crumbs [Russell] |
16481 | 'Or' expresses a mental state, not something about the world [Russell] |
16487 | Maybe the 'or' used to describe mental states is not the 'or' of logic [Russell] |
16483 | Disjunction may also arise in practice if there is imperfect memory. [Russell] |
10792 | The substitutional quantifier is not in competition with the standard interpretation [Kripke, by Marcus (Barcan)] |
13236 | Logical truth is much more important if mathematics rests on it, as logicism claims [Beall/Restall] |
16475 | A 'heterological' predicate can't be predicated of itself; so is 'heterological' heterological? Yes=no! [Russell] |
13237 | Preface Paradox affirms and denies the conjunction of propositions in the book [Beall/Restall] |
13244 | Relevant necessity is always true for some situation (not all situations) [Beall/Restall] |
16482 | All our knowledge (if verbal) is general, because all sentences contain general words [Russell] |
4758 | Naïve realism leads to physics, but physics then shows that naïve realism is false [Russell] |
16476 | For simple words, a single experience can show that they are true [Russell] |
16485 | Perception can't prove universal generalisations, so abandon them, or abandon empiricism? [Russell] |
13239 | Judgement is always predicating a property of a subject [Beall/Restall] |
13248 | We can rest truth-conditions on situations, rather than on possible worlds [Beall/Restall] |
13233 | Propositions commit to content, and not to any way of spelling it out [Beall/Restall] |
16478 | A mother cat is paralysed if equidistant between two needy kittens [Russell] |