11 ideas
11211 | If a sound conclusion comes from two errors that cancel out, the path of the argument must matter [Rumfitt] |
Full Idea: If a designated conclusion follows from the premisses, but the argument involves two howlers which cancel each other out, then the moral is that the path an argument takes from premisses to conclusion does matter to its logical evaluation. | |
From: Ian Rumfitt ("Yes" and "No" [2000], II) | |
A reaction: The drift of this is that our view of logic should be a little closer to the reasoning of ordinary language, and we should rely a little less on purely formal accounts. |
11210 | Standardly 'and' and 'but' are held to have the same sense by having the same truth table [Rumfitt] |
Full Idea: If 'and' and 'but' really are alike in sense, in what might that likeness consist? Some philosophers of classical logic will reply that they share a sense by virtue of sharing a truth table. | |
From: Ian Rumfitt ("Yes" and "No" [2000]) | |
A reaction: This is the standard view which Rumfitt sets out to challenge. |
11212 | The sense of a connective comes from primitively obvious rules of inference [Rumfitt] |
Full Idea: A connective will possess the sense that it has by virtue of its competent users' finding certain rules of inference involving it to be primitively obvious. | |
From: Ian Rumfitt ("Yes" and "No" [2000], III) | |
A reaction: Rumfitt cites Peacocke as endorsing this view, which characterises the logical connectives by their rules of usage rather than by their pure semantic value. |
16641 | Whiteness does not exist, but by it something can exist-as-white [Aquinas] |
Full Idea: Whiteness is said to exist not because it subsists in itself, but because by it something has existence-as-white. | |
From: Thomas Aquinas (Quodlibeta [1267], IX.2.2), quoted by Robert Pasnau - Metaphysical Themes 1274-1671 10.2 | |
A reaction: It seems unavoidable to refer to the whiteness as 'it'. It might be called the 'adverbial' theory of properties, as ways of doing something. |
14361 | Lewis says indicative conditionals are truth-functional [Lewis, by Jackson] |
Full Idea: Unlike Stalnaker, Lewis holds that indicative conditionals have the truth conditions of material conditionals. | |
From: report of David Lewis (Counterfactuals [1973]) by Frank Jackson - Conditionals 'Further' | |
A reaction: Thus Lewis only uses the possible worlds account for subjunctive conditionals, where Stalnaker uses it for both. Lewis is defending the truth-functional account for the indicative conditionals. |
8434 | In good counterfactuals the consequent holds in world like ours except that the antecedent is true [Lewis, by Horwich] |
Full Idea: According to Lewis, a counterfactual holds when the consequent is true in possible worlds very like our own except for the fact that the antecedent is true. | |
From: report of David Lewis (Counterfactuals [1973]) by Paul Horwich - Lewis's Programme p.213 | |
A reaction: Presumably the world being very like our own would make it unlikely that there would be anything else to cause the consequent, apart from the counterfactual antecedent. |
22170 | Senses grasp external properties, but the understanding grasps the essential natures of things [Aquinas] |
Full Idea: Our imagination and senses grasp only the outer properties of things, not their natures. ...Understanding, however, grasps the very substance and nature of things, so that what is represented in understanding is a likeness of thing's very essence. | |
From: Thomas Aquinas (Quodlibeta [1267], 8.2.2) | |
A reaction: This is exactly the picture I endorse for modern science. Explanation is the path to understanding, and that must venture beyond immediate experience. |
22169 | Initial universal truths are present within us as potential, to be drawn out by reason [Aquinas] |
Full Idea: For present in us by nature are certain initial truths everyone knows, in which lie potentially known conclusions our reasons can draw out and make actually known. | |
From: Thomas Aquinas (Quodlibeta [1267], 8.2.2) | |
A reaction: Note that these are truths rather than concepts, but that they have to be 'drawn out' by reason. This is Descartes' view of the matter, where the 'natural light' of reason is needed to articulate what is innate, such as geometry. |
22168 | Minds take in a likeness of things, which activates an awaiting potential [Aquinas] |
Full Idea: What the mind takes in is not some material element of the agent, but a likeness of the agent actualising some potential the patient already has. This, for example, is the way our seeing takes in the colour of a coloured body. | |
From: Thomas Aquinas (Quodlibeta [1267], 8.2.1) | |
A reaction: This is exactly right. Descartes agreed. It works for colour, but not (obviously) for cheese graters. |
11214 | We learn 'not' along with affirmation, by learning to either affirm or deny a sentence [Rumfitt] |
Full Idea: The standard view is that affirming not-A is more complex than affirming the atomic sentence A itself, with the latter determining its sense. But we could learn 'not' directly, by learning at once how to either affirm A or reject A. | |
From: Ian Rumfitt ("Yes" and "No" [2000], IV) | |
A reaction: [compressed] This seems fairly anti-Fregean in spirit, because it looks at the psychology of how we learn 'not' as a way of clarifying what we mean by it, rather than just looking at its logical behaviour (and thus giving it a secondary role). |
9419 | A law of nature is a general axiom of the deductive system that is best for simplicity and strength [Lewis] |
Full Idea: A contingent generalization is a law of nature if and only if it appears as a theorem (or axiom) in each of the true deductive systems that achieves a best combination of simplicity and strength. | |
From: David Lewis (Counterfactuals [1973], 3.3) |