34 ideas
| 1922 | Spiritual qualities only become advantageous with the growth of wisdom [Plato] |
| 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] |
| 11259 | How can you seek knowledge of something if you don't know it? [Plato] |
| 8075 | Space and time are atomic in the arrow, and divisible in the tortoise [Devlin] |
| 20219 | True opinions only become really valuable when they are tied down by reasons [Plato] |
| 5985 | Seeking and learning are just recollection [Plato] |
| 5986 | The slave boy learns geometry from questioning, not teaching, so it is recollection [Plato] |
| 1923 | As a guide to action, true opinion is as good as knowledge [Plato] |
| 1919 | You don't need to learn what you know, and how do you seek for what you don't know? [Plato] |
| 8088 | People still say the Hopi have no time concepts, despite Whorf's later denial [Devlin] |
| 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] |
| 1913 | Is virtue taught, or achieved by practice, or a natural aptitude, or what? [Plato] |
| 1921 | If virtue is a type of knowledge then it ought to be taught [Plato] |
| 1927 | It seems that virtue is neither natural nor taught, but is a divine gift [Plato] |
| 1918 | How can you know part of virtue without knowing the whole? [Plato] |
| 1916 | Even if virtues are many and various, they must have something in common to make them virtues [Plato] |
| 21244 | Conceiving a greater being than God leads to absurdity [Anselm] |
| 21241 | Even the fool can hold 'a being than which none greater exists' in his understanding [Anselm] |
| 21242 | If that than which a greater cannot be thought actually exists, that is greater than the mere idea [Anselm] |
| 1421 | A perfection must be independent and unlimited, and the necessary existence of Anselm's second proof gives this [Malcolm on Anselm] |
| 21245 | The word 'God' can be denied, but understanding shows God must exist [Anselm] |
| 21246 | Guanilo says a supremely fertile island must exist, just because we can conceive it [Anselm] |
| 21247 | Nonexistence is impossible for the greatest thinkable thing, which has no beginning or end [Anselm] |
| 21243 | An existing thing is even greater if its non-existence is inconceivable [Anselm] |
| 1420 | Anselm's first proof fails because existence isn't a real predicate, so it can't be a perfection [Malcolm on Anselm] |