33 ideas
| 15527 | Defining terms either enables elimination, or shows that they don't require elimination [Lewis] |
| 13838 | A decent modern definition should always imply a semantics [Hacking] |
| 13833 | 'Thinning' ('dilution') is the key difference between deduction (which allows it) and induction [Hacking] |
| 13834 | Gentzen's Cut Rule (or transitivity of deduction) is 'If A |- B and B |- C, then A |- C' [Hacking] |
| 13835 | Only Cut reduces complexity, so logic is constructive without it, and it can be dispensed with [Hacking] |
| 13845 | The various logics are abstractions made from terms like 'if...then' in English [Hacking] |
| 13840 | First-order logic is the strongest complete compact theory with Löwenheim-Skolem [Hacking] |
| 13844 | A limitation of first-order logic is that it cannot handle branching quantifiers [Hacking] |
| 13842 | Second-order completeness seems to need intensional entities and possible worlds [Hacking] |
| 13837 | With a pure notion of truth and consequence, the meanings of connectives are fixed syntactically [Hacking] |
| 13839 | Perhaps variables could be dispensed with, by arrows joining places in the scope of quantifiers [Hacking] |
| 13843 | If it is a logic, the Löwenheim-Skolem theorem holds for it [Hacking] |
| 15530 | A logically determinate name names the same thing in every possible world [Lewis] |
| 15528 | A Ramsey sentence just asserts that a theory can be realised, without saying by what [Lewis] |
| 15526 | There is a method for defining new scientific terms just using the terms we already understand [Lewis] |
| 15529 | It is better to have one realisation of a theory than many - but it may not always be possible [Lewis] |
| 15531 | The Ramsey sentence of a theory says that it has at least one realisation [Lewis] |
| 3847 | Man is nothing else but the sum of his actions [Sartre] |
| 3846 | Man IS freedom [Sartre] |
| 3843 | There is no human nature [Sartre] |
| 20762 | There are no values to justify us, and no excuses [Sartre] |
| 3852 | If values depend on us, freedom is the foundation of all values [Sartre] |
| 20764 | In becoming what we want to be we create what we think man ought to be [Sartre] |
| 3848 | Cowards are responsible for their cowardice [Sartre] |
| 20763 | When my personal freedom becomes involved, I must want freedom for everyone else [Sartre] |
| 22229 | Existentialists says that cowards and heroes make themselves [Sartre] |
| 3842 | Existence before essence (or begin with the subjective) [Sartre] |
| 6868 | 'Existence precedes essence' means we have no pre-existing self, but create it through existence [Sartre, by Le Poidevin] |
| 3844 | Existentialism says man is whatever he makes of himself [Sartre] |
| 20754 | It is dishonest to offer passions as an excuse [Sartre] |
| 6571 | When a man must choose between his mother and the Resistance, no theory can help [Sartre, by Fogelin] |
| 3851 | If I do not choose, that is still a choice [Sartre] |
| 3845 | Without God there is no intelligibility or value [Sartre] |