14 ideas
| 14970 | Normal system K has five axioms and rules [Cresswell] |
| 14971 | D is valid on every serial frame, but not where there are dead ends [Cresswell] |
| 14972 | S4 has 14 modalities, and always reduces to a maximum of three modal operators [Cresswell] |
| 14973 | In S5 all the long complex modalities reduce to just three, and their negations [Cresswell] |
| 14976 | Reject the Barcan if quantifiers are confined to worlds, and different things exist in other worlds [Cresswell] |
| 14974 | A relation is 'Euclidean' if aRb and aRc imply bRc [Cresswell] |
| 11993 | Jones may cease to exist without some simple property, but that doesn't make it essential [Kung] |
| 11997 | A property may belong essentially to one thing and contingently to another [Kung] |
| 11992 | Aristotelian essences underlie a thing's existence, explain it, and must belong to it [Kung] |
| 14975 | A de dicto necessity is true in all worlds, but not necessarily of the same thing in each world [Cresswell] |
| 11995 | Some peripheral properties are explained by essential ones, but don't themselves explain properties [Kung] |
| 11996 | Some non-essential properties may explain more than essential-but-peripheral ones do [Kung] |
| 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] |