19 ideas
18901 | Truthmakers are facts 'of' a domain, not something 'in' the domain [Sommers] |
18904 | 'Predicable' terms come in charged pairs, with one the negation of the other [Sommers, by Engelbretsen] |
18895 | Logic which maps ordinary reasoning must be transparent, and free of variables [Sommers] |
10282 | Logic is the study of sound argument, or of certain artificial languages (or applying the latter to the former) [Hodges,W] |
18897 | Predicate logic has to spell out that its identity relation '=' is an equivalent relation [Sommers] |
18893 | Translating into quantificational idiom offers no clues as to how ordinary thinkers reason [Sommers] |
18903 | Sommers promotes the old idea that negation basically refers to terms [Sommers, by Engelbretsen] |
18894 | Predicates form a hierarchy, from the most general, down to names at the bottom [Sommers] |
10283 | A formula needs an 'interpretation' of its constants, and a 'valuation' of its variables [Hodges,W] |
10285 | I |= φ means that the formula φ is true in the interpretation I [Hodges,W] |
10284 | There are three different standard presentations of semantics [Hodges,W] |
10289 | Up Löwenheim-Skolem: if infinite models, then arbitrarily large models [Hodges,W] |
10288 | Down Löwenheim-Skolem: if a countable language has a consistent theory, that has a countable model [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] |
18900 | Unfortunately for realists, modern logic cannot say that some fact exists [Sommers] |
18898 | In standard logic, names are the only way to refer [Sommers] |
7861 | Libet says the processes initiated in the cortex can still be consciously changed [Libet, by Papineau] |
6660 | Libet found conscious choice 0.2 secs before movement, well after unconscious 'readiness potential' [Libet, by Lowe] |