display all the ideas for this combination of texts
10 ideas
| 14980 | There is a real issue over what is the 'correct' logic [Sider] |
| Full Idea: Certain debates over the 'correct' logic are genuine, and not linguistic or conceptual. | |
| From: Theodore Sider (Writing the Book of the World [2011], 01.3) | |
| A reaction: It is rather hard to give arguments in favour of this view, but I am pleased to have the authority of Sider with me. |
| 15000 | 'It is raining' and 'it is not raining' can't be legislated, so we can't legislate 'p or ¬p' [Sider] |
| Full Idea: I cannot legislate-true 'It is raining' and I cannot legislate true 'It is not raining', so if I cannot legislate either true then I cannot legislate-true the disjunction 'it is raining or it is not raining'. | |
| From: Theodore Sider (Writing the Book of the World [2011], 06.5) | |
| A reaction: This strikes me as a very simple and very persuasive argument against the idea that logic is a mere convention. I take disjunction to be an abstract summary of how the world works. Sider seems sympathetic. |
| 15020 | Classical logic is good for mathematics and science, but less good for natural language [Sider] |
| Full Idea: Despite its brilliant success in mathematics and fundamental science, classical logic applies uneasily to natural language. | |
| From: Theodore Sider (Writing the Book of the World [2011], 10.6) | |
| A reaction: He gives examples of the conditional, and debates over the meaning of 'and', 'or' and 'not', and also names and quantifiers. Many modern philosophical problems result from this conflict. |
| 15029 | Modal accounts of logical consequence are simple necessity, or essential use of logical words [Sider] |
| Full Idea: The simplest modal account is that logical consequence is just necessary consequence; another modal account says that logical consequences are modal consequences that involve only logical words essentially. | |
| From: Theodore Sider (Writing the Book of the World [2011], 12.3) | |
| A reaction: [He cites Quine's 'Carnap and Logical Truth' for the second idea] Sider is asserting that Humeans like him dislike modality, and hence need a nonmodal account of logical consequence. |
| 9119 | No attempt to deny bivalence has ever been accepted [Sorensen] |
| Full Idea: The history of deviant logics is without a single success. Bivalence has been denied at least since Aristotle, yet no anti-bivalent theory has ever left the philosophical nursery. | |
| From: Roy Sorensen (Vagueness and Contradiction [2001], Intro) | |
| A reaction: This is part of a claim that nothing in reality is vague - it is just our ignorance of the truth or falsity of some propositions. Personally I don't see why 'Grandad is bald' has to have a determinate truth value. |
| 15019 | Define logical constants by role in proofs, or as fixed in meaning, or as topic-neutral [Sider] |
| Full Idea: Some say that logical constants are those expressions that are defined by their proof-theoretic roles, others that they are the expressions whose semantic values are permutation-invariant, and still others that they are the topic-neutral expressions. | |
| From: Theodore Sider (Writing the Book of the World [2011], 10.3) | |
| A reaction: [He cites MacFarlane 2005 as giving a survey of this] |
| 9135 | We now see that generalizations use variables rather than abstract entities [Sorensen] |
| Full Idea: As philosophers gradually freed themselves from the assumption that all words are names, ..they realised that generalizations really use variables rather than names of abstract entities. | |
| From: Roy Sorensen (Vagueness and Contradiction [2001], 8.4) | |
| A reaction: This looks like a key thought in trying to understand abstraction - though I don't think you can shake it off that easily. (For all x)(x-is-a-bird then x-has-wings) seems to require a generalised concept of a bird to give a value to the variable. |
| 15001 | 'Tonk' is supposed to follow the elimination and introduction rules, but it can't be so interpreted [Sider] |
| Full Idea: 'Tonk' is stipulated by Prior to stand for a meaning that obeys the elimination and introduction rules; but there simply is no such meaning; 'tonk' cannot be interpreted so as to obey the rules. | |
| From: Theodore Sider (Writing the Book of the World [2011], 06.5) | |
| A reaction: 'Tonk' thus seems to present a problem for so-called 'natural' deduction, if the natural deduction consists of nothing more than obey elimination and introduction rules. |
| 9125 | Denying problems, or being romantically defeated by them, won't make them go away [Sorensen] |
| Full Idea: An unsolvable problem is still a problem, despite Wittgenstein's view that there are no genuine philosophical problems, and Kant's romantic defeatism in his treatment of the antinomies of pure reason. | |
| From: Roy Sorensen (Vagueness and Contradiction [2001], 4.3) | |
| A reaction: I like the spin put on Kant, that he is a romantic in his defeatism. He certainly seems reluctant to slash at the Gordian knot, e.g. by being a bit more drastically sceptical about free will. |
| 9137 | Banning self-reference would outlaw 'This very sentence is in English' [Sorensen] |
| Full Idea: The old objection to the ban on self-reference is that it is too broad; it bans innocent sentences such as 'This very sentence is in English'. | |
| From: Roy Sorensen (Vagueness and Contradiction [2001], 11.1) | |
| A reaction: Tricky. What is the sigificant difference between 'this sentence is in English' and 'this sentence is a lie'? The first concerns context and is partly metalinguistic. The second concerns semantics and truth. Concept and content.. |