44 ideas
| 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] |
| 14273 | Conditional Proof is only valid if we accept the truth-functional reading of 'if' [Edgington] |
| 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] |
| 17518 | Counting 'coin in this box' may have coin as the unit, with 'in this box' merely as the scope [Ayers] |
| 17516 | If counting needs a sortal, what of things which fall under two sortals? [Ayers] |
| 17520 | Events do not have natural boundaries, and we have to set them [Ayers] |
| 17519 | To express borderline cases of objects, you need the concept of an 'object' [Ayers] |
| 17511 | Recognising continuity is separate from sortals, and must precede their use [Ayers] |
| 17510 | Speakers need the very general category of a thing, if they are to think about it [Ayers] |
| 17522 | We use sortals to classify physical objects by the nature and origin of their unity [Ayers] |
| 17515 | Seeing caterpillar and moth as the same needs continuity, not identity of sortal concepts [Ayers] |
| 17517 | Could the same matter have more than one form or principle of unity? [Ayers] |
| 17513 | If there are two objects, then 'that marble, man-shaped object' is ambiguous [Ayers] |
| 17523 | Sortals basically apply to individuals [Ayers] |
| 17521 | You can't have the concept of a 'stage' if you lack the concept of an object [Ayers] |
| 17514 | Temporal 'parts' cannot be separated or rearranged [Ayers] |
| 17509 | Some say a 'covering concept' completes identity; others place the concept in the reference [Ayers] |
| 17512 | If diachronic identities need covering concepts, why not synchronic identities too? [Ayers] |
| 7800 | Analytic truths are divided into logically and conceptually necessary [Girle] |
| 7801 | Possibilities can be logical, theoretical, physical, economic or human [Girle] |
| 14281 | A thing works like formal probability if all the options sum to 100% [Edgington] |
| 14284 | Conclusion improbability can't exceed summed premise improbability in valid arguments [Edgington] |
| 14270 | Simple indicatives about past, present or future do seem to form a single semantic kind [Edgington] |
| 14269 | Maybe forward-looking indicatives are best classed with the subjunctives [Edgington] |
| 14275 | Truth-function problems don't show up in mathematics [Edgington] |
| 14274 | Inferring conditionals from disjunctions or negated conjunctions gives support to truth-functionalism [Edgington] |
| 14276 | The truth-functional view makes conditionals with unlikely antecedents likely to be true [Edgington] |
| 14290 | Doctor:'If patient still alive, change dressing'; Nurse:'Either dead patient, or change dressing'; kills patient! [Edgington] |
| 14271 | Non-truth-functionalist say 'If A,B' is false if A is T and B is F, but deny that is always true for TT,FT and FF [Edgington] |
| 14272 | I say "If you touch that wire you'll get a shock"; you don't touch it. How can that make the conditional true? [Edgington] |
| 14282 | On the supposition view, believe if A,B to the extent that A&B is nearly as likely as A [Edgington] |
| 14278 | Truth-functionalists support some conditionals which we assert, but should not actually believe [Edgington] |
| 14287 | Does 'If A,B' say something different in each context, because of the possibiites there? [Edgington] |
| 7792 | A world has 'access' to a world it generates, which is important in possible worlds semantics [Girle] |