29 ideas
17926 | Rejecting double negation elimination undermines reductio proofs [Colyvan] |
17925 | Showing a disproof is impossible is not a proof, so don't eliminate double negation [Colyvan] |
17924 | Excluded middle says P or not-P; bivalence says P is either true or false [Colyvan] |
17929 | Löwenheim proved his result for a first-order sentence, and Skolem generalised it [Colyvan] |
17930 | Axioms are 'categorical' if all of their models are isomorphic [Colyvan] |
17928 | Ordinal numbers represent order relations [Colyvan] |
17923 | Intuitionists only accept a few safe infinities [Colyvan] |
17941 | Infinitesimals were sometimes zero, and sometimes close to zero [Colyvan] |
17922 | Reducing real numbers to rationals suggested arithmetic as the foundation of maths [Colyvan] |
17936 | Transfinite induction moves from all cases, up to the limit ordinal [Colyvan] |
17940 | Most mathematical proofs are using set theory, but without saying so [Colyvan] |
17931 | Structuralism say only 'up to isomorphism' matters because that is all there is to it [Colyvan] |
17932 | If 'in re' structures relies on the world, does the world contain rich enough structures? [Colyvan] |
5163 | Basic propositions refer to a single experience, are incorrigible, and conclusively verifiable [Ayer] |
17943 | Probability supports Bayesianism better as degrees of belief than as ratios of frequencies [Colyvan] |
17939 | Mathematics can reveal structural similarities in diverse systems [Colyvan] |
17938 | Mathematics can show why some surprising events have to occur [Colyvan] |
17934 | Proof by cases (by 'exhaustion') is said to be unexplanatory [Colyvan] |
17933 | Reductio proofs do not seem to be very explanatory [Colyvan] |
17935 | If inductive proofs hold because of the structure of natural numbers, they may explain theorems [Colyvan] |
17942 | Can a proof that no one understands (of the four-colour theorem) really be a proof? [Colyvan] |
5167 | The argument from analogy fails, so the best account of other minds is behaviouristic [Ayer] |
17937 | Mathematical generalisation is by extending a system, or by abstracting away from it [Colyvan] |
5164 | A statement is meaningful if observation statements can be deduced from it [Ayer] |
5165 | Directly verifiable statements must entail at least one new observation statement [Ayer] |
5166 | The principle of verification is not an empirical hypothesis, but a definition [Ayer] |
5162 | Sentences only express propositions if they are meaningful; otherwise they are 'statements' [Ayer] |
7667 | There are two sides to men - the pleasantly social, and the violent and creative [Diderot, by Berlin] |
5168 | Moral approval and disapproval concerns classes of actions, rather than particular actions [Ayer] |