20 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] |
15375 | If terms change their designations in different states, they are functions from states to objects [Fitting] |
15376 | Intensional logic adds a second type of quantification, over intensional objects, or individual concepts [Fitting] |
15378 | Awareness logic adds the restriction of an awareness function to epistemic logic [Fitting] |
15379 | Justication logics make explicit the reasons for mathematical truth in proofs [Fitting] |
9406 | A class is natural when everybody can spot further members of it [Quinton] |
11026 | Classical logic is deliberately extensional, in order to model mathematics [Fitting] |
11028 | λ-abstraction disambiguates the scope of modal operators [Fitting] |
15730 | Extreme nominalists say all classification is arbitrary convention [Quinton] |
14974 | A relation is 'Euclidean' if aRb and aRc imply bRc [Cresswell] |
15728 | The naturalness of a class depends as much on the observers as on the objects [Quinton] |
9407 | Properties imply natural classes which can be picked out by everybody [Quinton] |
15729 | Uninstantiated properties must be defined using the instantiated ones [Quinton] |
8520 | An individual is a union of a group of qualities and a position [Quinton, by Campbell,K] |
14975 | A de dicto necessity is true in all worlds, but not necessarily of the same thing in each world [Cresswell] |
15377 | Definite descriptions pick out different objects in different possible worlds [Fitting] |