26 ideas
| 23269 | Philosophy must start from clearly observed facts [Galen] |
| 5750 | Consistency is modal, saying propositions are consistent if they could be true together [Melia] |
| 5737 | Predicate logic has connectives, quantifiers, variables, predicates, equality, names and brackets [Melia] |
| 5744 | First-order predicate calculus is extensional logic, but quantified modal logic is intensional (hence dubious) [Melia] |
| 5740 | Second-order logic needs second-order variables and quantification into predicate position [Melia] |
| 5741 | If every model that makes premises true also makes conclusion true, the argument is valid [Melia] |
| 5735 | Maybe names and predicates can capture any fact [Melia] |
| 5736 | No sort of plain language or levels of logic can express modal facts properly [Melia] |
| 5746 | The Identity of Indiscernibles is contentious for qualities, and trivial for non-qualities [Melia] |
| 5738 | We may be sure that P is necessary, but is it necessarily necessary? [Melia] |
| 5732 | 'De re' modality is about things themselves, 'de dicto' modality is about propositions [Melia] |
| 5739 | Sometimes we want to specify in what ways a thing is possible [Melia] |
| 5734 | Possible worlds make it possible to define necessity and counterfactuals without new primitives [Melia] |
| 5742 | In possible worlds semantics the modal operators are treated as quantifiers [Melia] |
| 5743 | If possible worlds semantics is not realist about possible worlds, logic becomes merely formal [Melia] |
| 5749 | Possible worlds could be real as mathematics, propositions, properties, or like books [Melia] |
| 5751 | The truth of propositions at possible worlds are implied by the world, just as in books [Melia] |
| 23266 | The spirit in the soul wants freedom, power and honour [Galen] |
| 23219 | Stopping the heart doesn't terminate activity; pressing the brain does that [Galen, by Cobb] |
| 23264 | Philosophers think faculties are in substances, and invent a faculty for every activity [Galen] |
| 23220 | The brain contains memory and reason, and is the source of sensation and decision [Galen] |
| 23265 | The rational part of the soul is the desire for truth, understanding and recollection [Galen] |
| 5748 | We accept unverifiable propositions because of simplicity, utility, explanation and plausibility [Melia] |
| 23268 | We execute irredeemable people, to protect ourselves, as a deterrent, and ending a bad life [Galen] |
| 1748 | Archelaus was the first person to say that the universe is boundless [Archelaus, by Diog. Laertius] |
| 5989 | Archelaus said life began in a primeval slime [Archelaus, by Schofield] |