20 ideas
23367 | Even pointing a finger should only be done for a reason [Epictetus] |
10282 | Logic is the study of sound argument, or of certain artificial languages (or applying the latter to the former) [Hodges,W] |
10283 | A formula needs an 'interpretation' of its constants, and a 'valuation' of its variables [Hodges,W] |
10284 | There are three different standard presentations of semantics [Hodges,W] |
10285 | I |= φ means that the formula φ is true in the interpretation I [Hodges,W] |
10288 | Down Löwenheim-Skolem: if a countable language has a consistent theory, that has a countable model [Hodges,W] |
10289 | Up Löwenheim-Skolem: if infinite models, then arbitrarily large models [Hodges,W] |
10287 | If a first-order theory entails a sentence, there is a finite subset of the theory which entails it [Hodges,W] |
10286 | A 'set' is a mathematically well-behaved class [Hodges,W] |
20657 | There are 23 core brain functions, with known circuit, transmitters, genes and behaviour [Watson] |
20656 | Traditional ideas of the mind were weakened in the 1950s by mind-influencing drugs [Watson] |
20655 | Humans have been hunter-gatherers for 99.5% of their existence [Watson] |
20650 | The Uncertainty Principle implies that cause and effect can't be measured [Watson] |
20649 | The interference of light through two slits confirmed that it is waves [Watson] |
20661 | Electrons rotate in hyrogen atoms 10^13 times per second [Watson] |
20647 | Quantum theory explains why nature is made up of units, such as elements [Watson] |
20654 | Only four particles are needed for matter: up and down quark, electron, electron-neutrino [Watson] |
20651 | The shape of molecules is important, as well as the atoms and their bonds [Watson] |
20652 | In 1828 the animal substance urea was manufactured from inorganic ingredients [Watson] |
20658 | Information is physical, and living can be seen as replicating and preserving information [Watson] |