25 ideas
15557 | Verisimilitude has proved hard to analyse, and seems to have several components [Lewis] |
Full Idea: The analysis of verisimilitude has been much debated. Some plausible analyses have failed disastrously, others conflict with one another. One conclusion is that verisimilitude seems to consist of several distinguishable virtues. | |
From: David Lewis (Causal Explanation [1986], V n7) | |
A reaction: Presumably if it is complex, you can approach truth in one respect while receding from it in another. It seems clear enough if you are calculating pi by some iterative process. |
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. |
14352 | '¬', '&', and 'v' are truth functions: the truth of the compound is fixed by the truth of the components [Jackson] |
Full Idea: It is widely agreed that '¬', '&', and 'v' are 'truth functions': the truth value of a compound sentence formed using them is fully determined by the truth value or values of the component sentences. | |
From: Frank Jackson (Conditionals [2006], 'Equiv') | |
A reaction: A candidate for not being a truth function might be a conditional →, where the arrow adds something over and above the propositions it connects. The relationship has an additional truth value? Does A depend on B? |
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. |
15554 | A disposition needs a causal basis, a property in a certain causal role. Could the disposition be the property? [Lewis] |
Full Idea: I take for granted that a disposition requires a causal basis: one has the disposition iff one has a property that occupies a certain causal role. Shall we then identify the disposition with its basis? That makes the disposition cause its manifestations. | |
From: David Lewis (Causal Explanation [1986], III) | |
A reaction: Introduce the concept of a 'power' and I see no problem with his proposal. Fundamental dispositions are powerful, and provide the causal basis for complex dispositions. Something had better be powerful. |
15560 | We can explain a chance event, but can never show why some other outcome did not occur [Lewis] |
Full Idea: I think we are right to explain chance events, yet we are right also to deny that we can ever explain why a chance process yields one outcome rather than another. We cannot explain why one event happened rather than the other. | |
From: David Lewis (Causal Explanation [1986], VI) | |
A reaction: This misses out an investigation which slowly reveals that a 'chance' event wasn't so chancey after all. Failure to explain confirms chance, so the judgement of chance shouldn't block attempts to explain. |
14360 | Possible worlds for subjunctives (and dispositions), and no-truth for indicatives? [Jackson] |
Full Idea: Subjunctive conditionals are intimately connected with dispositional properties and causation. ...Consequently, a position some find attractive is that possible worlds theory applies to subjunctives, while the no-truth theory applies to indicatives. | |
From: Frank Jackson (Conditionals [2006], 'Indicative') | |
A reaction: My intuitions are to reject this and favour a unified account, where both sorts of conditionals are mappings of the relationships among the facts of actuality. Nice slogan! |
14353 | Modus ponens requires that A→B is F when A is T and B is F [Jackson] |
Full Idea: Modus ponens is intuitively valid, but in A,A→B|B if A is true and B is false that must be because A→B is false. So A→B is false when A is true and B is false. | |
From: Frank Jackson (Conditionals [2006], 'Equiv') | |
A reaction: This is his first step in showing how the truth functional account of A→B acquires its truth table. If you are giving up the truth functional view of conditionals, presumably you are not also going to give up modus ponens? |
14354 | When A and B have the same truth value, A→B is true, because A→A is a logical truth [Jackson] |
Full Idea: (A→A) is a logical truth, so some conditionals with antecedent and consequent the same truth value are true. But if '→' is a truth function, that will be true for all cases. Hence whenever A and B are alike in truth value, (A→B) is true. | |
From: Frank Jackson (Conditionals [2006], 'Equiv') | |
A reaction: His second step in demonstrating the truth table for →, assuming it is truth functional. |
14355 | (A&B)→A is a logical truth, even if antecedent false and consequent true, so it is T if A is F and B is T [Jackson] |
Full Idea: (A&B)→A is a logical truth, but A can be true and B false, so that (A&B) is false. So some conditionals with false antecedent and true consequent are true. If → is a truth function, then whenever A is false and B is true (A→B) is true. | |
From: Frank Jackson (Conditionals [2006], 'Equiv') | |
A reaction: This is his third and final step in showing the truth table of → if it is truth functional. |
14358 | In the possible worlds account of conditionals, modus ponens and modus tollens are validated [Jackson] |
Full Idea: In the possible worlds account modus ponens is validated (the closest world, the actual, is a B-world just if B is true), and modus tollens is validated (if B is false, the actual world is not an A-world, so A is false). | |
From: Frank Jackson (Conditionals [2006], 'Famous') | |
A reaction: [see Jackson for slightly fuller versions] This looks like a minimal requirement for a decent theory of conditionals, so Jackson explains the attractions of the possible worlds view very persuasively. |
14359 | Only assertions have truth-values, and conditionals are not proper assertions [Jackson] |
Full Idea: In the no-truth theory of conditionals they have justified assertion or acceptability conditions but not truth conditions. ...The motivation is that only assertions have truth values, and conditionals are arguments, not proper assertions. | |
From: Frank Jackson (Conditionals [2006], 'No-truth') | |
A reaction: Once I trim this idea down to its basics, it suddenly looks very persuasive. Except that I am inclined to think that conditional truths do state facts about the world - perhaps as facts about how more basic truths are related to each other. |
14357 | Possible worlds account, unlike A⊃B, says nothing about when A is false [Jackson] |
Full Idea: In the possible worlds account of conditionals A⊃B is not sufficient for A→B. If A is false then A⊃B is true, but here nothing is implied about whether the world most like the actual world except that A is true is or is not a B-world. | |
From: Frank Jackson (Conditionals [2006], 'Possible') | |
A reaction: The possible worlds account seems to be built on Ramsey's idea of just holding A true and seeing what you get. Being committed to B being automatically true if A is false seems highly counterintuitive. |
14356 | We can't insist that A is relevant to B, as conditionals can express lack of relevance [Jackson] |
Full Idea: One addition to the truth functional account of conditionals is that A be somehow relevant to B. However, sometimes we use conditionals to express lack of relevance, as in 'If Fred works he will fail, and if Fred doesn't work he will fail'. | |
From: Frank Jackson (Conditionals [2006], 'Possible') | |
A reaction: This certainly seems to put paid to an attractive instant solution to the problem. |
15559 | Does a good explanation produce understanding? That claim is just empty [Lewis] |
Full Idea: It is said that a good explanation ought to produce understanding, ...but this just says that a good explanation produces possession of that which it provide, so this desideratum is empty. It adds nothing to our understanding of explanation. | |
From: David Lewis (Causal Explanation [1986], V) | |
A reaction: I am not convinced by this dismissal. If you are looking for a test of whether an explanation is good, the announcement that the participants feel they have achieved a good understanding sounds like success. |
15556 | Science may well pursue generalised explanation, rather than laws [Lewis] |
Full Idea: The pursuit of general explanations may be very much more widespread in science than the pursuit of general laws. | |
From: David Lewis (Causal Explanation [1986], IV) | |
A reaction: Nice. I increasingly think that the main target of all enquiry is ever-widening generality, with no need to aspire to universality. |
15558 | A good explanation is supposed to show that the event had to happen [Lewis] |
Full Idea: It is said that a good explanation ought to show that the explanandum event had to happen, given the laws and circumstances. | |
From: David Lewis (Causal Explanation [1986], V) | |
A reaction: I cautiously go along with this view. Given that there are necessities in nature (a long story), we should aim to reveal them. There is no higher aspiration open to us than successful explanation. Lewis says good explanations can reveal falsehoods. |
4809 | Lewis endorses the thesis that all explanation of singular events is causal explanation [Lewis, by Psillos] |
Full Idea: Lewis endorses the thesis that all explanation of singular events is causal explanation. | |
From: report of David Lewis (Causal Explanation [1986]) by Stathis Psillos - Causation and Explanation p.237 | |
A reaction: It is hard to challenge this. The assumption is that only nomological and causal explanations are possible, and the former are unobtainable for singular events. |
14321 | To explain an event is to provide some information about its causal history [Lewis] |
Full Idea: Here is my main thesis: to explain an event is to provide some information about its causal history. | |
From: David Lewis (Causal Explanation [1986], II) | |
A reaction: The obvious thought is that you might provide some tiny and barely relevant part of that causal history, such as a bird perched on the Titanic's iceberg. So how do we distinguish the 'important' causal information? |
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). |
15555 | Explaining match lighting in general is like explaining one lighting of a match [Lewis] |
Full Idea: Explaining why struck matches light in general is not so very different from explaining why some particular struck match lit. ...We may generalize modestly, without laying claim to universality. | |
From: David Lewis (Causal Explanation [1986], IV) | |
A reaction: A suggestive remark, since particular causation and general causation seem far apart, but Lewis suggests that the needs of explanation bring them together. Lawlike and unlawlike explanations? |
15551 | Ways of carving causes may be natural, but never 'right' [Lewis] |
Full Idea: There is no one right way - though there may be more or less natural ways - of carving up a causal history. | |
From: David Lewis (Causal Explanation [1986], I) | |
A reaction: This invites a distinction between the 'natural' causes and the 'real' causes. Presumably if any causes were 'real', they would have a better claim to be 'right'. Is an earthquake the 'real' (correct?) cause of a tsunami? |
15552 | We only pick 'the' cause for the purposes of some particular enquiry. [Lewis] |
Full Idea: Disagreement about 'the' cause is only disagreement about which part of the causal history is most salient for the purposes of some particular inquiry. | |
From: David Lewis (Causal Explanation [1986], I) | |
A reaction: I don't believe this. In the majority of cases I see the cause of an event, without having any interest in any particular enquiry. It is just so obvious that there isn't even a disagreement. Maybe there is only one sensible enquiry. |
15553 | Causal dependence is counterfactual dependence between events [Lewis] |
Full Idea: I take causal dependence to be counterfactual dependence, of a suitably back-tracking sort, between distinct events. | |
From: David Lewis (Causal Explanation [1986], I) | |
A reaction: He quotes Hume in support. 'Counterfactual dependence' strikes me as too vague, or merely descriptive, for the job of explanation. 'If...then' is a logical relationship; what is it in nature that justifies the dependency? |