display all the ideas for this combination of texts
6 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. |
| 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. |
| 12664 | A truth-table, not inferential role, defines 'and' [Fodor] |
| Full Idea: I'm inclined to think that 'and' is defined by its truth-table (and not, for example, by its 'inferential-role'). | |
| From: Jerry A. Fodor (LOT 2 [2008], Ch.7) | |
| A reaction: Sounds right, on my general principle that something can only have a function if it has an intrinsic nature. The truth-table just formalises normal understanding of 'and', according to what it makes true. |
| 12648 | Names in thought afford a primitive way to bring John before the mind [Fodor] |
| Full Idea: Names in thought (in contrast to, say, descriptions in thought) afford a primitive way of bringing John before the mind. | |
| From: Jerry A. Fodor (LOT 2 [2008], Ch.3 App) | |
| A reaction: I think the 'file' account of concepts which Fodor has now latched onto gives a wonderful account of names. They are simple if you haven't opened the file yet (like 'Louis', in Evans's example). |
| 12650 | 'Paderewski' has two names in mentalese, for his pianist file and his politician file [Fodor] |
| Full Idea: Paderewski (as pianist and as politician) has two names in Mentalese. If you think there are two Paderewskis, it's important that what you get when you retrieve the pianist file differs from the politician file. You can then merge the two files. | |
| From: Jerry A. Fodor (LOT 2 [2008], Ch.3 App) | |
| A reaction: The same will apply to 'Hespherus' and 'Phosphorus'. We can re-separate the 'morning star' and 'evening star' files if we wish to discuss ancient Egyptian attitudes to such things. I love this idea of Fodor's. Explanations flow from it. |
| 12656 | P-and-Q gets its truth from the truth of P and truth of Q, but consistency isn't like that [Fodor] |
| Full Idea: The truth of P-and-Q is (roughly) a function of the truth of P and the truth of Q; but the consistency of P&Q isn't a function of the consistency of P and the consistency of Q. | |
| From: Jerry A. Fodor (LOT 2 [2008], Ch.4.5 n33) | |
| A reaction: This is a nice deep issue. Fodor is interested in artificial intelligence at this point, but I am interested in the notion of coherence, as found in good justifications. Even consistency isn't elementary logic, never mind coherence. |