20 ideas
| 8092 | Logic was merely a branch of rhetoric until the scientific 17th century [Devlin] |
| 8081 | 'No councillors are bankers' and 'All bankers are athletes' implies 'Some athletes are not councillors' [Devlin] |
| 8085 | Modern propositional inference replaces Aristotle's 19 syllogisms with modus ponens [Devlin] |
| 8086 | Predicate logic retains the axioms of propositional logic [Devlin] |
| 8091 | Situation theory is logic that takes account of context [Devlin] |
| 8087 | Golden ages: 1900-1960 for pure logic, and 1950-1985 for applied logic [Devlin] |
| 8089 | Montague's intensional logic incorporated the notion of meaning [Devlin] |
| 8082 | Where a conditional is purely formal, an implication implies a link between premise and conclusion [Devlin] |
| 8072 | Sentences of apparent identical form can have different contextual meanings [Devlin] |
| 8075 | Space and time are atomic in the arrow, and divisible in the tortoise [Devlin] |
| 10245 | One geometry cannot be more true than another [Poincaré] |
| 8088 | People still say the Hopi have no time concepts, despite Whorf's later denial [Devlin] |
| 23681 | The first motion or effect cannot be produced necessarily, so the First Cause must be a free agent [Reid] |
| 23676 | A willed action needs reasonable understanding of what is to be done [Reid] |
| 23680 | We are morally free, because we experience it, we are accountable, and we pursue projects [Reid] |
| 8073 | How do we parse 'time flies like an arrow' and 'fruit flies like an apple'? [Devlin] |
| 8076 | The distinction between sentences and abstract propositions is crucial in logic [Devlin] |
| 23678 | A motive is merely an idea, like advice, and not a force for action [Reid] |
| 23677 | We all know that mere priority or constant conjunction do not have to imply causation [Reid] |
| 23679 | The principle of the law of nature is that matter is passive, and is acted upon [Reid] |