display all the ideas for this combination of texts
8 ideas
| 8078 | Modus ponens is one of five inference rules identified by the Stoics [Chrysippus, by Devlin] |
| Full Idea: Modus ponens is just one of the five different inference rules identified by the Stoics. | |
| From: report of Chrysippus (fragments/reports [c.240 BCE]) by Keith Devlin - Goodbye Descartes Ch.2 | |
| A reaction: Modus ponens strikes me as being more like a definition of implication than a 'rule'. Implication is what gets you from one truth to another. All the implications of a truth must also be true. |
| 10454 | In first-order we can't just assert existence, and it is very hard to deny something's existence [Bach] |
| Full Idea: In standard logic we can't straightforwardly say that n exists. We have to resort to using a formula like '∃x(x=n)', but we can't deny n's existence by negating that formula, because standard first-order logic disallows empty names. | |
| From: Kent Bach (What Does It Take to Refer? [2006], 22.2 L1) |
| 6023 | Every proposition is either true or false [Chrysippus, by Cicero] |
| Full Idea: We hold fast to the position, defended by Chrysippus, that every proposition is either true or false. | |
| From: report of Chrysippus (fragments/reports [c.240 BCE]) by M. Tullius Cicero - On Fate ('De fato') 38 | |
| A reaction: I am intrigued to know exactly how you defend this claim. It may depend what you mean by a proposition. A badly expressed proposition may have indeterminate truth, quite apart from the vague, the undecidable etc. |
| 10453 | In logic constants play the role of proper names [Bach] |
| Full Idea: In standard first-order logic the role of proper names is played by individual constants. | |
| From: Kent Bach (What Does It Take to Refer? [2006], 22.2 L1) |
| 10452 | Proper names can be non-referential - even predicate as well as attributive uses [Bach] |
| Full Idea: Like it or not, proper names have non-referential uses, including not only attributive but even predicate uses. | |
| From: Kent Bach (What Does It Take to Refer? [2006], 22.2 L1) | |
| A reaction: 'He's a right little Hitler'. 'You're doing a George Bush again'. 'Try to live up to the name of Churchill'. |
| 10456 | Millian names struggle with existence, empty names, identities and attitude ascription [Bach] |
| Full Idea: The familiar problems with the Millian view of names are the problem of positive and negative existential statements, empty names, identity sentences, and propositional attitude ascription. | |
| From: Kent Bach (What Does It Take to Refer? [2006], 22.2 L1) | |
| A reaction: I take this combination of problems to make an overwhelming case against the daft idea that the semantics of a name amounts to the actual object it picks out. It is a category mistake to attempt to insert a person into a sentence. |
| 10440 | An object can be described without being referred to [Bach] |
| Full Idea: An object can be described without being referred to. | |
| From: Kent Bach (What Does It Take to Refer? [2006], Intro) | |
| A reaction: I'm not clear how this is possible for a well-known object, though it is clearly possible for a speculative object, such as a gadget I would like to buy. In the former case reference seems to occur even if the speaker is trying to avoid it. |
| 10444 | Definite descriptions can be used to refer, but are not semantically referential [Bach] |
| Full Idea: If Russell is, as I believe, basically right, then definite descriptions are the paradigm of singular terms that can be used to refer but are not linguistically (semantically) referential. | |
| From: Kent Bach (What Does It Take to Refer? [2006], 22.1 s5) | |
| A reaction: I'm not sure that we can decide what is 'semantically referential'. Most of the things we refer to don't have names. We don't then 'use' definite descriptions (I'm thinking) - they actually DO the job. If we use them, we can 'use' names too? |