30 ideas
| 5750 | Consistency is modal, saying propositions are consistent if they could be true together [Melia] |
| 5737 | Predicate logic has connectives, quantifiers, variables, predicates, equality, names and brackets [Melia] |
| 5744 | First-order predicate calculus is extensional logic, but quantified modal logic is intensional (hence dubious) [Melia] |
| 9967 | 'Impure' sets have a concrete member, while 'pure' (abstract) sets do not [Jubien] |
| 5740 | Second-order logic needs second-order variables and quantification into predicate position [Melia] |
| 9968 | A model is 'fundamental' if it contains only concrete entities [Jubien] |
| 5741 | If every model that makes premises true also makes conclusion true, the argument is valid [Melia] |
| 9965 | There couldn't just be one number, such as 17 [Jubien] |
| 9966 | The subject-matter of (pure) mathematics is abstract structure [Jubien] |
| 9963 | If we all intuited mathematical objects, platonism would be agreed [Jubien] |
| 9962 | How can pure abstract entities give models to serve as interpretations? [Jubien] |
| 9964 | Since mathematical objects are essentially relational, they can't be picked out on their own [Jubien] |
| 5736 | No sort of plain language or levels of logic can express modal facts properly [Melia] |
| 5735 | Maybe names and predicates can capture any fact [Melia] |
| 9969 | The empty set is the purest abstract object [Jubien] |
| 5746 | The Identity of Indiscernibles is contentious for qualities, and trivial for non-qualities [Melia] |
| 5738 | We may be sure that P is necessary, but is it necessarily necessary? [Melia] |
| 5732 | 'De re' modality is about things themselves, 'de dicto' modality is about propositions [Melia] |
| 14919 | Empiricists deny what is unobservable, and reject objective modality [Fraassen] |
| 5739 | Sometimes we want to specify in what ways a thing is possible [Melia] |
| 5734 | Possible worlds make it possible to define necessity and counterfactuals without new primitives [Melia] |
| 5742 | In possible worlds semantics the modal operators are treated as quantifiers [Melia] |
| 5743 | If possible worlds semantics is not realist about possible worlds, logic becomes merely formal [Melia] |
| 5749 | Possible worlds could be real as mathematics, propositions, properties, or like books [Melia] |
| 5751 | The truth of propositions at possible worlds are implied by the world, just as in books [Melia] |
| 6783 | To 'accept' a theory is not to believe it, but to believe it empirically adequate [Fraassen, by Bird] |
| 14917 | To accept a scientific theory, we only need to believe that it is empirically adequate [Fraassen] |
| 6784 | Why should the true explanation be one of the few we have actually thought of? [Fraassen, by Bird] |
| 13066 | An explanation is just descriptive information answering a particular question [Fraassen, by Salmon] |
| 5748 | We accept unverifiable propositions because of simplicity, utility, explanation and plausibility [Melia] |