14 ideas
| 12268 | Contradiction is impossible [Antisthenes (I), by Aristotle] |
| Full Idea: Antisthenes said that contradiction is impossible. | |
| From: report of Antisthenes (Ath) (fragments/reports [c.405 BCE]) by Aristotle - Topics 104b21 | |
| A reaction: Aristotle is giving an example of a 'thesis'. It should be taken seriously if a philosopher proposes it, but dismissed as rubbish if anyone else proposes it! No context is given for the remark. |
| 602 | Some fools think you cannot define anything, but only say what it is like [Antisthenes (I), by Aristotle] |
| Full Idea: There is an application of that old chestnut of the cynic Antisthenes' followers (and other buffoons of that kind). Their claim was that a definition of what something is is impossible. You cannot define silver, though you can say it is like tin. | |
| From: report of Antisthenes (Ath) (fragments/reports [c.405 BCE]) by Aristotle - Metaphysics 1043b |
| 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) |
| 1664 | I would rather go mad than experience pleasure [Antisthenes (I)] |
| Full Idea: I would rather go mad than experience pleasure. | |
| From: Antisthenes (Ath) (fragments/reports [c.405 BCE]), quoted by Diogenes Laertius - Lives of Eminent Philosophers 06.3 | |
| A reaction: Did he actually prefer pain? If both experiences would drive him mad, it seems like a desire for death. I cannot understand why anyone is opposed to harmless pleasures. |
| 21385 | Antisthenes said virtue is teachable and permanent, is life's goal, and is like universal wealth [Antisthenes (I), by Long] |
| Full Idea: The moral propositions of Antisthenes foreshadowed the Stoics: virtue can be taught and once acquired cannot be lost (fr.69,71); virtue is the goal of life (22); the sage is self-sufficient, since he has (by being wise) the wealth of all men (8o). | |
| From: report of Antisthenes (Ath) (fragments/reports [c.405 BCE]) by A.A. Long - Hellenistic Philosophy 1 | |
| A reaction: [He cites Caizzi for the fragments] The distinctive idea here is (I think) that once acquired virtue can never be lost. It sounds plausible, but I'm wondering why it should be true. Is it like riding a bicycle, or like learning to speak Russian? |
| 20239 | Unlike us, the early Greeks thought envy was a good thing, and hope a bad thing [Hesiod, by Nietzsche] |
| Full Idea: Hesiod reckons envy among the effects of the good and benevolent Eris, and there was nothing offensive in according envy to the gods. ...Likewise the Greeks were different from us in their evaluation of hope: one felt it to be blind and malicious. | |
| From: report of Hesiod (works [c.700 BCE]) by Friedrich Nietzsche - Dawn (Daybreak) 038 | |
| A reaction: Presumably this would be understandable envy, and unreasonable hope. Ridiculous envy can't possibly be good, and modest and sensible hope can't possibly be bad. I suspect he wants to exaggerate the relativism. |
| 2631 | Antisthenes says there is only one god, which is nature [Antisthenes (I), by Cicero] |
| Full Idea: Antisthenes says there is only one god, which is nature. | |
| From: report of Antisthenes (Ath) (fragments/reports [c.405 BCE]) by M. Tullius Cicero - On the Nature of the Gods ('De natura deorum') I.32 |