25 ideas
13917 | Metaphysics aims to identify categories of being, and show their interdependency [Lowe] |
13919 | Philosophy aims not at the 'analysis of concepts', but at understanding the essences of things [Lowe] |
4037 | Ockham's Razor is the principle that we need reasons to believe in entities [Mellor/Oliver] |
7786 | Propositional logic handles negation, disjunction, conjunction; predicate logic adds quantifiers, predicates, relations [Girle] |
7798 | There are three axiom schemas for propositional logic [Girle] |
7799 | Proposition logic has definitions for its three operators: or, and, and identical [Girle] |
7797 | Axiom systems of logic contain axioms, inference rules, and definitions of proof and theorems [Girle] |
7794 | There are seven modalities in S4, each with its negation [Girle] |
7793 | ◊p → □◊p is the hallmark of S5 [Girle] |
7795 | S5 has just six modalities, and all strings can be reduced to those [Girle] |
7787 | Possible worlds logics use true-in-a-world rather than true [Girle] |
7788 | Modal logic has four basic modal negation equivalences [Girle] |
7796 | Modal logics were studied in terms of axioms, but now possible worlds semantics is added [Girle] |
7789 | Necessary implication is called 'strict implication'; if successful, it is called 'entailment' [Girle] |
7790 | If an argument is invalid, a truth tree will indicate a counter-example [Girle] |
4027 | Properties are respects in which particular objects may be alike or differ [Mellor/Oliver] |
4029 | Nominalists ask why we should postulate properties at all [Mellor/Oliver] |
13918 | Holes, shadows and spots of light can coincide without being identical [Lowe] |
13921 | All things must have an essence (a 'what it is'), or we would be unable to think about them [Lowe] |
13922 | Knowing an essence is just knowing what the thing is, not knowing some further thing [Lowe] |
13920 | Each thing has to be of a general kind, because it belongs to some category [Lowe] |
7800 | Analytic truths are divided into logically and conceptually necessary [Girle] |
7801 | Possibilities can be logical, theoretical, physical, economic or human [Girle] |
7792 | A world has 'access' to a world it generates, which is important in possible worlds semantics [Girle] |
4039 | Abstractions lack causes, effects and spatio-temporal locations [Mellor/Oliver] |