47 ideas
| 10455 | Free logic at least allows empty names, but struggles to express non-existence [Bach] |
| 10775 | The axiom of choice now seems acceptable and obvious (if it is meaningful) [Tharp] |
| 10766 | Logic is either for demonstration, or for characterizing structures [Tharp] |
| 10767 | Elementary logic is complete, but cannot capture mathematics [Tharp] |
| 10769 | Second-order logic isn't provable, but will express set-theory and classic problems [Tharp] |
| 10454 | In first-order we can't just assert existence, and it is very hard to deny something's existence [Bach] |
| 10762 | In sentential logic there is a simple proof that all truth functions can be reduced to 'not' and 'and' [Tharp] |
| 10453 | In logic constants play the role of proper names [Bach] |
| 10452 | Proper names can be non-referential - even predicate as well as attributive uses [Bach] |
| 10456 | Millian names struggle with existence, empty names, identities and attitude ascription [Bach] |
| 10440 | An object can be described without being referred to [Bach] |
| 10444 | Definite descriptions can be used to refer, but are not semantically referential [Bach] |
| 10776 | The main quantifiers extend 'and' and 'or' to infinite domains [Tharp] |
| 10774 | There are at least five unorthodox quantifiers that could be used [Tharp] |
| 10777 | Skolem mistakenly inferred that Cantor's conceptions were illusory [Tharp] |
| 10773 | The Löwenheim-Skolem property is a limitation (e.g. can't say there are uncountably many reals) [Tharp] |
| 10765 | Soundness would seem to be an essential requirement of a proof procedure [Tharp] |
| 10763 | Completeness and compactness together give axiomatizability [Tharp] |
| 10770 | If completeness fails there is no algorithm to list the valid formulas [Tharp] |
| 10771 | Compactness is important for major theories which have infinitely many axioms [Tharp] |
| 10772 | Compactness blocks infinite expansion, and admits non-standard models [Tharp] |
| 10764 | A complete logic has an effective enumeration of the valid formulas [Tharp] |
| 10768 | Effective enumeration might be proved but not specified, so it won't guarantee knowledge [Tharp] |
| 3338 | Numbers have been defined in terms of 'successors' to the concept of 'zero' [Peano, by Blackburn] |
| 13949 | All models of Peano axioms are isomorphic, so the models all seem equally good for natural numbers [Cartwright,R on Peano] |
| 18113 | PA concerns any entities which satisfy the axioms [Peano, by Bostock] |
| 17634 | Peano axioms not only support arithmetic, but are also fairly obvious [Peano, by Russell] |
| 5897 | 0 is a non-successor number, all successors are numbers, successors can't duplicate, if P(n) and P(n+1) then P(all-n) [Peano, by Flew] |
| 15653 | We can add Reflexion Principles to Peano Arithmetic, which assert its consistency or soundness [Halbach on Peano] |
| 17635 | Arithmetic can have even simpler logical premises than the Peano Axioms [Russell on Peano] |
| 12900 | How could 'S knows he has hands' not have a fixed content? [Bach] |
| 12901 | If contextualism is right, knowledge sentences are baffling out of their context [Bach] |
| 12902 | Sceptics aren't changing the meaning of 'know', but claiming knowing is tougher than we think [Bach] |
| 10446 | Fictional reference is different inside and outside the fiction [Bach] |
| 10447 | We can refer to fictional entities if they are abstract objects [Bach] |
| 10443 | You 'allude to', not 'refer to', an individual if you keep their identity vague [Bach] |
| 10439 | What refers: indefinite or definite or demonstrative descriptions, names, indexicals, demonstratives? [Bach] |
| 10441 | If we can refer to things which change, we can't be obliged to single out their properties [Bach] |
| 10442 | We can think of an individual without have a uniquely characterizing description [Bach] |
| 10445 | It can't be real reference if it could refer to some other thing that satisfies the description [Bach] |
| 10457 | Since most expressions can be used non-referentially, none of them are inherently referential [Bach] |
| 10463 | Just alluding to or describing an object is not the same as referring to it [Bach] |
| 10459 | Context does not create reference; it is just something speakers can exploit [Bach] |
| 10460 | 'That duck' may not refer to the most obvious one in the group [Bach] |
| 10461 | What a pronoun like 'he' refers back to is usually a matter of speaker's intentions [Bach] |
| 10462 | Information comes from knowing who is speaking, not just from interpretation of the utterance [Bach] |
| 10458 | People slide from contextual variability all the way to contextual determination [Bach] |