15 ideas
| 23367 | Even pointing a finger should only be done for a reason [Epictetus] |
| Full Idea: Philosophy says it is not right even to stretch out a finger without some reason. | |
| From: Epictetus (fragments/reports [c.57], 15) | |
| A reaction: The key point here is that philosophy concerns action, an idea on which Epictetus is very keen. He rather despise theory. This idea perfectly sums up the concept of the wholly rational life (which no rational person would actually want to live!). |
| 13917 | Metaphysics aims to identify categories of being, and show their interdependency [Lowe] |
| Full Idea: The central task of metaphysics is to chart the possibilities of existence by identifying the categories of being and the relations of ontological dependency in which beings of different categories stand to one another. | |
| From: E.J. Lowe (Two Notions of Being: Entity and Essence [2008], Intro) | |
| A reaction: I am beginning to think that he is right about the second one, and that dependency and grounding relations are the name of the game. I don't have Lowe's confidence that philosophers can parcel up reality in neat and true ways. |
| 13919 | Philosophy aims not at the 'analysis of concepts', but at understanding the essences of things [Lowe] |
| Full Idea: The central task of philosophy is the cultivation of insights into natures or essences, and not the 'analysis of concepts', with which it is apt to be confused. | |
| From: E.J. Lowe (Two Notions of Being: Entity and Essence [2008], 1) | |
| A reaction: This immediately strikes me as a false dichotomy. I like the idea of trying to understand the true natures of things, but how are we going to do it in our armchairs? |
| 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) |
| 13918 | Holes, shadows and spots of light can coincide without being identical [Lowe] |
| Full Idea: Holes are things of such a kind that they can coincide without being identical - as are, for example, shadows and spots of light. | |
| From: E.J. Lowe (Two Notions of Being: Entity and Essence [2008], 1) | |
| A reaction: His point is that they thereby fail one of the standard tests for being an 'object'. |
| 13921 | All things must have an essence (a 'what it is'), or we would be unable to think about them [Lowe] |
| Full Idea: Things must have an essence, in the sense of 'what it is to be the individual of that kind', or it would make no sense to say we can talk or think comprehendingly about things at all. If we don't know what it is, how can we think about it? | |
| From: E.J. Lowe (Two Notions of Being: Entity and Essence [2008], 2) | |
| A reaction: Lowe presents this as a sort of Master Argument for essences. I think he is working with the wrong notion of essence. All he means is that things must have identities to be objects of thought. Why equate identity with essence, and waste a good concept? |
| 13922 | Knowing an essence is just knowing what the thing is, not knowing some further thing [Lowe] |
| Full Idea: To know something's essence is not to be acquainted with some further thing of a special kind, but simply to understand what exactly that thing is. | |
| From: E.J. Lowe (Two Notions of Being: Entity and Essence [2008], 2) | |
| A reaction: I think he is wrong about this, or at least is working with an unhelpful notion of essence. Identity is one thing, and essence is another. I take essences to be certain selected features of things, which explain their nature. |
| 13920 | Each thing has to be of a general kind, because it belongs to some category [Lowe] |
| Full Idea: Any individual thing must be a thing of some general kind - because, at the very least, it must belong to some ontological category. | |
| From: E.J. Lowe (Two Notions of Being: Entity and Essence [2008], 2) | |
| A reaction: Where does the law that 'everything must have a category' come from? I'm baffled by remarks of this kind. Where do we get the categories from? From observing the individuals. So which has priority? Not the categories. Is God a kind? |