34 ideas
| 3993 | Arguments are nearly always open to challenge, but they help to explain a position rather than force people to believe [Lewis] |
| 7798 | There are three axiom schemas for propositional logic [Girle] |
| 7786 | Propositional logic handles negation, disjunction, conjunction; predicate logic adds quantifiers, predicates, relations [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] |
| 7796 | Modal logics were studied in terms of axioms, but now possible worlds semantics is added [Girle] |
| 7788 | Modal logic has four basic modal negation equivalences [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] |
| 3990 | The whole truth supervenes on the physical truth [Lewis] |
| 3991 | Where pixels make up a picture, supervenience is reduction [Lewis] |
| 11976 | Aristotelian essentialism says essences are not relative to specification [Lewis] |
| 7800 | Analytic truths are divided into logically and conceptually necessary [Girle] |
| 11978 | Causal necessities hold in all worlds compatible with the laws of nature [Lewis] |
| 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] |
| 11979 | It doesn't take the whole of a possible Humphrey to win the election [Lewis] |
| 16994 | Counterpart theory is bizarre, as no one cares what happens to a mere counterpart [Kripke on Lewis] |
| 11974 | Counterparts are not the original thing, but resemble it more than other things do [Lewis] |
| 11975 | If the closest resembler to you is in fact quite unlike you, then you have no counterpart [Lewis] |
| 11977 | Essential attributes are those shared with all the counterparts [Lewis] |
| 3995 | A mind is an organ of representation [Lewis] |
| 3994 | Human pain might be one thing; Martian pain might be something else [Lewis] |
| 3989 | I am a reductionist about mind because I am an a priori reductionist about everything [Lewis] |
| 3992 | Folk psychology makes good predictions, by associating mental states with causal roles [Lewis] |
| 3996 | Folk psychology doesn't say that there is a language of thought [Lewis] |
| 3998 | If you don't share an external world with a brain-in-a-vat, then externalism says you don't share any beliefs [Lewis] |
| 3997 | Nothing shows that all content is 'wide', or that wide content has logical priority [Lewis] |
| 3999 | A spontaneous duplicate of you would have your brain states but no experience, so externalism would deny him any beliefs [Lewis] |
| 4000 | Wide content derives from narrow content and relationships with external things [Lewis] |