46 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] |
22886 | The modern idea of 'limit' allows infinite quantities to have a finite sum [Bardon] |
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] |
22914 | An equally good question would be why there was nothing instead of something [Bardon] |
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] |
17937 | Mathematical generalisation is by extending a system, or by abstracting away from it [Colyvan] |
6005 | Animals are dangerous and nourishing, and can't form contracts of justice [Hermarchus, by Sedley] |
22902 | Why does an effect require a prior event if the prior event isn't a cause? [Bardon] |
22905 | Becoming disordered is much easier for a system than becoming ordered [Bardon] |
22913 | The universe expands, so space-time is enlarging [Bardon] |
22889 | We should treat time as adverbial, so we don't experience time, we experience things temporally [Bardon, by Bardon] |
22900 | How can we question the passage of time, if the question takes time to ask? [Bardon] |
22898 | What is time's passage relative to, and how fast does it pass? [Bardon] |
22897 | The A-series says a past event is becoming more past, but how can it do that? [Bardon] |
22901 | The B-series needs a revised view of causes, laws and explanations [Bardon] |
22896 | The B-series is realist about time, but idealist about its passage [Bardon] |
22903 | The B-series adds directionality when it accepts 'earlier' and 'later' [Bardon] |
22910 | To define time's arrow by causation, we need a timeless definition of causation [Bardon] |
22909 | We judge memories to be of the past because the events cause the memories [Bardon] |
22904 | The psychological arrow of time is the direction from our memories to our anticipations [Bardon] |
22906 | The direction of entropy is probabilistic, not necessary, so cannot be identical to time's arrow [Bardon] |
22907 | It is arbitrary to reverse time in a more orderly universe, but not in a sub-system of it [Bardon] |
22883 | It seems hard to understand change without understanding time first [Bardon] |
22890 | We experience static states (while walking round a house) and observe change (ship leaving dock) [Bardon] |
22884 | The motion of a thing should be a fact in the present moment [Bardon] |
22892 | Experiences of motion may be overlapping, thus stretching out the experience [Bardon] |
22911 | At least eternal time gives time travellers a possible destination [Bardon] |
22912 | Time travel is not a paradox if we include it in the eternal continuum of events [Bardon] |
22882 | We use calendars for the order of events, and clocks for their passing [Bardon] |