35 ideas
| 10476 | The idea that groups of concepts could be 'implicitly defined' was abandoned [Hodges,W] |
| 13913 | The four 'perfect syllogisms' are called Barbara, Celarent, Darii and Ferio [Engelbretsen/Sayward] |
| 13914 | Syllogistic logic has one rule: what is affirmed/denied of wholes is affirmed/denied of their parts [Engelbretsen/Sayward] |
| 13915 | Syllogistic can't handle sentences with singular terms, or relational terms, or compound sentences [Engelbretsen/Sayward] |
| 13916 | Term logic uses expression letters and brackets, and '-' for negative terms, and '+' for compound terms [Engelbretsen/Sayward] |
| 10282 | Logic is the study of sound argument, or of certain artificial languages (or applying the latter to the former) [Hodges,W] |
| 13850 | In modern logic all formal validity can be characterised syntactically [Engelbretsen/Sayward] |
| 10478 | Since first-order languages are complete, |= and |- have the same meaning [Hodges,W] |
| 13849 | Classical logic rests on truth and models, where constructivist logic rests on defence and refutation [Engelbretsen/Sayward] |
| 10477 | |= in model-theory means 'logical consequence' - it holds in all models [Hodges,W] |
| 13851 | Unlike most other signs, = cannot be eliminated [Engelbretsen/Sayward] |
| 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] |
| 10474 | |= should be read as 'is a model for' or 'satisfies' [Hodges,W] |
| 10475 | A 'structure' is an interpretation specifying objects and classes of quantification [Hodges,W] |
| 10473 | Model theory studies formal or natural language-interpretation using set-theory [Hodges,W] |
| 10481 | Models in model theory are structures, not sets of descriptions [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] |
| 13852 | Axioms are ω-incomplete if the instances are all derivable, but the universal quantification isn't [Engelbretsen/Sayward] |
| 10287 | If a first-order theory entails a sentence, there is a finite subset of the theory which entails it [Hodges,W] |
| 10480 | First-order logic can't discriminate between one infinite cardinal and another [Hodges,W] |
| 10286 | A 'set' is a mathematically well-behaved class [Hodges,W] |
| 7439 | The qualities involved in sensations are entirely intentional [Anscombe, by Armstrong] |
| 8353 | Freedom involves acting according to an idea [Anscombe] |
| 8352 | To believe in determinism, one must believe in a system which determines events [Anscombe] |
| 20041 | Intentional actions are those which are explained by giving the reason for so acting [Anscombe] |
| 8070 | It would be better to point to failings of character, than to moral wrongness of actions [Anscombe] |
| 8065 | 'Ought' and 'right' are survivals from earlier ethics, and should be jettisoned [Anscombe] |
| 8069 | Between Aristotle and us, a Judaeo-Christian legal conception of ethics was developed [Anscombe] |
| 8351 | With diseases we easily trace a cause from an effect, but we cannot predict effects [Anscombe] |
| 4777 | The word 'cause' is an abstraction from a group of causal terms in a language (scrape, push..) [Anscombe] |
| 10363 | Causation is relative to how we describe the primary relata [Anscombe, by Schaffer,J] |
| 8350 | Since Mill causation has usually been explained by necessary and sufficient conditions [Anscombe] |