33 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] |
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] |
13165 | Geometrical proofs do not show causes, as when we prove a triangle contains two right angles [Proclus] |
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] |
17937 | Mathematical generalisation is by extending a system, or by abstracting away from it [Colyvan] |
9569 | The origin of geometry started in sensation, then moved to calculation, and then to reason [Proclus] |
7096 | We may still admire a person's character even if the traits are involuntary [Statman] |
7098 | There is a new sort of moral scepticism, about the possibility of moral theories [Statman] |
7099 | With a broad concept of flourishing, it might be possible without the virtues [Statman] |
7100 | Virtue theory isn't a genuine ethical theory, because it doesn't have universal application [Statman] |
7102 | Promises create moral duties that have nothing to do with character [Statman] |
7095 | Moral education is better by concrete example than abstract principle [Statman] |
7094 | Friends express friendship even when no utility is involved [Statman] |
7093 | Behaviour may be disgusting or inhumane, but violate no duty [Statman] |
7104 | The ancients recognised imperfect duties, but we have added perfect duties like justice [Statman] |
7103 | Abortion issues focus on the mother's right over her body, and the status of the foetus [Statman] |