15 ideas
| 13913 | The four 'perfect syllogisms' are called Barbara, Celarent, Darii and Ferio [Engelbretsen/Sayward] |
| Full Idea: There are four 'perfect syllogisms': Barbara (every M is P, every S is M, so every S is P); Celarent (no M is P, every S is M, so no S is P); Darii (every M is P, some S is M, so some S is P); Ferio (no M is P, some S is M, so some S is not P). | |
| From: Engelbretsen,G/Sayward,C (Philosophical Logic: Intro to Advanced Topics [2011], 8) | |
| A reaction: The four names are mnemonics from medieval universities. |
| 13914 | Syllogistic logic has one rule: what is affirmed/denied of wholes is affirmed/denied of their parts [Engelbretsen/Sayward] |
| Full Idea: It has often been claimed (e.g. by Leibniz) that a single rule governs all syllogistic validity, called 'dictum de omni et null', which says that what is affirmed or denied of any whole is affirmed or denied of any part of that whole. | |
| From: Engelbretsen,G/Sayward,C (Philosophical Logic: Intro to Advanced Topics [2011], 8) | |
| A reaction: This seems to be the rule which is captured by Venn Diagrams. |
| 13915 | Syllogistic can't handle sentences with singular terms, or relational terms, or compound sentences [Engelbretsen/Sayward] |
| Full Idea: Three common kinds of sentence cannot be put into syllogistic ('categorical') form: ones using singular terms ('Mars is red'), ones using relational terms ('every painter owns some brushes'), and compound sentences. | |
| From: Engelbretsen,G/Sayward,C (Philosophical Logic: Intro to Advanced Topics [2011], 8) |
| 13916 | Term logic uses expression letters and brackets, and '-' for negative terms, and '+' for compound terms [Engelbretsen/Sayward] |
| Full Idea: Term logic begins with expressions and two 'term functors'. Any simple letter is a 'term', any term prefixed by a minus ('-') is a 'negative term', and any pair of terms flanking a plus ('+') is a 'compound term'. Parenthese are used for grouping. | |
| From: Engelbretsen,G/Sayward,C (Philosophical Logic: Intro to Advanced Topics [2011], 8) | |
| A reaction: [see Engelbretsen and Sayward for the full formal system] |
| 13850 | In modern logic all formal validity can be characterised syntactically [Engelbretsen/Sayward] |
| Full Idea: One of the key ideas of modern formal logic is that all formally valid inferences can be specified in strictly syntactic terms. | |
| From: Engelbretsen,G/Sayward,C (Philosophical Logic: Intro to Advanced Topics [2011], Ch.2) |
| 13849 | Classical logic rests on truth and models, where constructivist logic rests on defence and refutation [Engelbretsen/Sayward] |
| Full Idea: Classical logic rests on the concepts of truth and falsity (and usually makes use of a semantic theory based on models), whereas constructivist logic accounts for inference in terms of defense and refutation. | |
| From: Engelbretsen,G/Sayward,C (Philosophical Logic: Intro to Advanced Topics [2011], Intro) | |
| A reaction: My instincts go with the classical view, which is that inferences do not depend on the human capacity to defend them, but sit there awaiting revelation. My view isn't platonist, because I take the inferences to be rooted in the physical world. |
| 13851 | Unlike most other signs, = cannot be eliminated [Engelbretsen/Sayward] |
| Full Idea: Unlike ∨, →, ↔, and ∀, the sign = is not eliminable from a logic. | |
| From: Engelbretsen,G/Sayward,C (Philosophical Logic: Intro to Advanced Topics [2011], Ch.3) |
| 13852 | Axioms are ω-incomplete if the instances are all derivable, but the universal quantification isn't [Engelbretsen/Sayward] |
| Full Idea: A set of axioms is said to be ω-incomplete if, for some universal quantification, each of its instances is derivable from those axioms but the quantification is not thus derivable. | |
| From: Engelbretsen,G/Sayward,C (Philosophical Logic: Intro to Advanced Topics [2011], 7) |
| 2986 | Belief is the most important propositional attitude [Lyons] |
| Full Idea: Belief might be accorded the status of core or chief propositional attitude. | |
| From: William Lyons (Approaches to Intentionality [1995], p.126) |
| 20653 | Six reduction levels: groups, lives, cells, molecules, atoms, particles [Putnam/Oppenheim, by Watson] |
| Full Idea: There are six 'reductive levels' in science: social groups, (multicellular) living things, cells, molecules, atoms, and elementary particles. | |
| From: report of H.Putnam/P.Oppenheim (Unity of Science as a Working Hypothesis [1958]) by Peter Watson - Convergence 10 'Intro' | |
| A reaction: I have the impression that fields are seen as more fundamental that elementary particles. What is the status of the 'laws' that are supposed to govern these things? What is the status of space and time within this picture? |
| 2978 | Consciousness no longer seems essential to intentionality [Lyons] |
| Full Idea: In contrast with Brentano and Husserl, consciousness or attention are no longer seen as essential to intentionality. | |
| From: William Lyons (Approaches to Intentionality [1995], Intro) | |
| A reaction: This strikes me as being correct, although there seem to be plenty of current philosophers who do not accept it (e.g. Searle). I think philosophy of mind may be stuck in the dark ages if thinkers don't accept this proposal. |
| 2984 | Perceptions could give us information without symbolic representation [Lyons] |
| Full Idea: It is possible to give an account of concept-formation without a language of thought or representation, based on perception, which in the brain seems to involve information without representation. | |
| From: William Lyons (Approaches to Intentionality [1995], p.66) | |
| A reaction: This claim strikes me as being a little too confident. One might say that a concept IS a representation. However, the perception of several horses might 'blur' together to form a generalised horse. |
| 2979 | Propositional attitudes require representation [Lyons] |
| Full Idea: How else, other than via some form of representational system, could a human organism contain information as a content over which it could operate or 'attitudinise'? | |
| From: William Lyons (Approaches to Intentionality [1995], Intro) | |
| A reaction: Depends what you mean by 'representational'. In its vaguest sense, this is just a tautology - content must be held in the mind in some form or other, but that tells us nothing. |
| 2987 | Folk psychology works badly for alien cultures [Lyons] |
| Full Idea: It is not easy to employ our folk psychology in the understanding of persons in a very different culture. | |
| From: William Lyons (Approaches to Intentionality [1995], p.241) | |
| A reaction: This strikes me as a highly significant problem for the friends of folk psychology. It also breaks down in extreme situations, or with mental illness. It seems closer to culture than to brain structure. |
| 2977 | All thinking has content [Lyons] |
| Full Idea: I cannot say I am simply thinking but not thinking about anything. | |
| From: William Lyons (Approaches to Intentionality [1995], Intro) | |
| A reaction: Hard to disagree. However, I can plausibly reply to 'What are you thinking?' with 'Nothing', if my consciousness is freewheeling. Utterly disconnected content isn't really what we call 'thinking'. |