32 ideas
| 22438 | Philosophy is largely concerned with finding the minimum that science could get by with [Quine] |
| Full Idea: Philosophy is in large part concerned with ...what science could get along with, could be reconstructed by means of, as distinct from what science has historically made us of. | |
| From: Willard Quine (Mr Strawson on Logical Theory [1953], V) | |
| A reaction: This nicely summarises the programme for the whole of the philosophy of David Lewis, who was Quine's pupil. If you start by asking what it could 'get by with', it is not surprising that simplicity is the top intellectual virtue for both of them. |
| 22436 | Logicians don't paraphrase logic into language, because they think in the symbolic language [Quine] |
| Full Idea: The logician does not even need to paraphrase the vernacular into his logical notation, for he has learned to think directly in his logical notation, or even (which is the beauty of the thing) to let it think for him. | |
| From: Willard Quine (Mr Strawson on Logical Theory [1953], V) | |
| A reaction: See Williamson's love of logic (and his book on modal metaphysics). This idea embodies the dream of hardcore Frege-Russellian analytic philosophers. I wish someone had told me when I studied logic that the target was to actually think symbolically. |
| 22431 | Good algorithms and theories need many occurrences of just a few elements [Quine] |
| Full Idea: The power and simplicity of an algorithm, or indeed of any theory, depend on there being many occurrences of few elements rather than few occurrences of many. | |
| From: Willard Quine (Mr Strawson on Logical Theory [1953], III) | |
| A reaction: Not sure how this applies to a software function. One which produces a good result from a large number of input variables sounds particularly impressive to me. Many occurrences of a single variable sounds rather inefficient. |
| 22435 | The logician's '→' does not mean the English if-then [Quine] |
| Full Idea: The logician drops 'if-then' in favour of '→' without ever entertaining the mistaken idea that they are synonymous. | |
| From: Willard Quine (Mr Strawson on Logical Theory [1953], V) | |
| A reaction: [Quine uses the older horseshoe symbol] The conditional in English is not well understood, whereas the symbol is unambiguous. A warning to myself, since I have a tendency to translate symbols into English all the time. [p.156 'implies' is worse!] |
| 14970 | Normal system K has five axioms and rules [Cresswell] |
| Full Idea: Normal propositional modal logics derive from the minimal system K: wffs of PC are axioms; □(p⊃q)⊃(□p⊃□q); uniform substitution; modus ponens; necessitation (α→□α). | |
| From: Max J. Cresswell (Modal Logic [2001], 7.1) |
| 14971 | D is valid on every serial frame, but not where there are dead ends [Cresswell] |
| Full Idea: If a frame contains any dead end or blind world, then D is not valid on that frame, ...but D is valid on every serial frame. | |
| From: Max J. Cresswell (Modal Logic [2001], 7.1.1) |
| 14972 | S4 has 14 modalities, and always reduces to a maximum of three modal operators [Cresswell] |
| Full Idea: In S4 there are exactly 14 distinct modalities, and any modality may be reduced to one containing no more than three modal operators in sequence. | |
| From: Max J. Cresswell (Modal Logic [2001], 7.1.2) | |
| A reaction: The significance of this may be unclear, but it illustrates one of the rewards of using formal systems to think about modal problems. There is at least an appearance of precision, even if it is only conditional precision. |
| 14973 | In S5 all the long complex modalities reduce to just three, and their negations [Cresswell] |
| Full Idea: S5 contains the four main reduction laws, so the first of any pair of operators may be deleted. Hence all but the last modal operator may be deleted. This leaves six modalities: p, ◊p, □p, and their negations. | |
| From: Max J. Cresswell (Modal Logic [2001], 7.1.2) |
| 22433 | It is important that the quantification over temporal entities is timeless [Quine] |
| Full Idea: It would be hard to exaggerate the importance of recognising the timelessness of quantification over temporal entities. | |
| From: Willard Quine (Mr Strawson on Logical Theory [1953], IV) | |
| A reaction: 'Some moments in this cricket match were crucial'. The domain is not timeless, but consists of moments in this match. Can you say the quantifier is timeless but its domain is not? Only in the sense that 'very' is a timeless word, I think. |
| 14976 | Reject the Barcan if quantifiers are confined to worlds, and different things exist in other worlds [Cresswell] |
| Full Idea: If one wants the quantifiers in each world to range only over the things that exist in that world, and one doesn't believe that the same things exist in every world, one would probably not want the Barcan formula. | |
| From: Max J. Cresswell (Modal Logic [2001], 7.2.2) | |
| A reaction: I haven't quite got this, but it sounds to me like I should reject the Barcan formula (but Idea 9449!). I like a metaphysics to rest on the actual world (with modal properties). I assume different things could have existed, but don't. |
| 22437 | Logical languages are rooted in ordinary language, and that connection must be kept [Quine] |
| Full Idea: A logical language is not independent of ordinary language. It has its roots in ordinary language, and these roots are not to be severed. | |
| From: Willard Quine (Mr Strawson on Logical Theory [1953], V) | |
| A reaction: Music to my ears. When you study logic, no one has to teach you what the words 'or' and 'if-then' mean, but they are disambiguated by the symbolism. The roots of logic are in ordinary talk of 'and', 'or' and 'not', which is the real world. |
| 22434 | Reduction to logical forms first simplifies idioms and grammar, then finds a single reading of it [Quine] |
| Full Idea: Ordinary language is reduced to logical form in two ways: reduction of the variety of idioms and grammatical constructions, and reduction of each surviving idiom to one fixed and convenient interpretation. | |
| From: Willard Quine (Mr Strawson on Logical Theory [1953], V) | |
| A reaction: Is there a conflict between a 'fixed' and a 'convenient' result? By 'fixed' I suppose he means it is a commitment (to not waver). What is the logical form of a sentence which is deliberately ambiguous? |
| 14974 | A relation is 'Euclidean' if aRb and aRc imply bRc [Cresswell] |
| Full Idea: A relation is 'Euclidean' if aRb and aRc imply bRc. | |
| From: Max J. Cresswell (Modal Logic [2001], 7.1.2) | |
| A reaction: If a thing has a relation to two separate things, then those two things will also have that relation between them. If I am in the same family as Jim and as Jill, then Jim and Jill are in the same family. |
| 9476 | If dispositions are more fundamental than causes, then they won't conceptually reduce to them [Bird on Lewis] |
| Full Idea: Maybe a disposition is a more fundamental notion than a cause, in which case Lewis has from the very start erred in seeking a causal analysis, in a traditional, conceptual sense, of disposition terms. | |
| From: comment on David Lewis (Causation [1973]) by Alexander Bird - Nature's Metaphysics 2.2.8 | |
| A reaction: Is this right about Lewis? I see him as reducing both dispositions and causes to a set of bald facts, which exist in possible and actual worlds. Conditionals and counterfactuals also suffer the same fate. |
| 14975 | A de dicto necessity is true in all worlds, but not necessarily of the same thing in each world [Cresswell] |
| Full Idea: A de dicto necessary truth says that something is φ, that this proposition is a necessary truth, i.e. that in every accessible world something (but not necessarily the same thing in each world) is φ. | |
| From: Max J. Cresswell (Modal Logic [2001], 7.2.1) | |
| A reaction: At last, a really clear and illuminating account of this term! The question is then invited of what is the truthmaker for a de dicto truth, assuming that the objects themselves are truthmakers for de re truths. |
| 22432 | Normally conditionals have no truth value; it is the consequent which has a conditional truth value [Quine] |
| Full Idea: Ordinarily the conditional is not thought of as true or false at all, but rather the consequent is thought of as conditionally true or false given the antecedent. | |
| From: Willard Quine (Mr Strawson on Logical Theory [1953], III) | |
| A reaction: At first this seems obvious, but a conditional asserts a relationship between two propositions, and so presumably it is true if that relationship exists. 'Is it actually true that if it is Monday then everyone in the office is depressed?'. |
| 8425 | For true counterfactuals, both antecedent and consequent true is closest to actuality [Lewis] |
| Full Idea: A counterfactual is non-vacuously true iff it takes less of a departure from actuality to make the consequent true along with the antecedent than it does to make the antecedent true without the consequent. | |
| From: David Lewis (Causation [1973], p.197) | |
| A reaction: Almost every theory proposed by Lewis hangs on the meaning of the word 'close', as used here. If you visited twenty Earth-like worlds (watch Startrek?), it would be a struggle to decide their closeness to ours in rank order. |
| 8424 | Determinism says there can't be two identical worlds up to a time, with identical laws, which then differ [Lewis] |
| Full Idea: By determinism I mean that the prevailing laws of nature are such that there do not exist any two possible worlds which are exactly alike up to that time, which differ thereafter, and in which those laws are never violated. | |
| From: David Lewis (Causation [1973], p.196) | |
| A reaction: This would mean that the only way an action of free will could creep in would be if it accepted being a 'violation' of the laws of nature. Fans of free will would probably prefer to call it a 'natural' phenomenon. I'm with Lewis. |
| 22430 | If we understand a statement, we know the circumstances of its truth [Quine] |
| Full Idea: We understand under what circumstances to say of any given statement that it is true, just as clearly as we understand the statement itself. | |
| From: Willard Quine (Mr Strawson on Logical Theory [1953], II) | |
| A reaction: This probably shouldn't be taken as a theory of meaning (in which Quine doesn't really believe) but as a plausible statement of correlated facts. Hypothetical assertions might be a problem case. 'If only I could be in two places at once'? |
| 8420 | A proposition is a set of possible worlds where it is true [Lewis] |
| Full Idea: I identify a proposition with the set of possible worlds where it is true. | |
| From: David Lewis (Causation [1973], p.193) | |
| A reaction: As it stands, I'm baffled by this. How can 'it is raining' be a set of possible worlds? I assume it expands to refer to the truth-conditions, among possibilities as well as actualities. 'It is raining' fits all worlds where it is raining. |
| 8405 | A theory of causation should explain why cause precedes effect, not take it for granted [Lewis, by Field,H] |
| Full Idea: Lewis thinks it is a major defect in a theory of causation that it builds in the condition that the time of the cause precede that of the effect: that cause precedes effect is something we ought to explain (which his counterfactual theory claims to do). | |
| From: report of David Lewis (Causation [1973]) by Hartry Field - Causation in a Physical World | |
| A reaction: My immediate reaction is that the chances of explaining such a thing are probably nil, and that we might as well just accept the direction of causation as a given. Even philosophers balk at the question 'why doesn't time go backwards?' |
| 8427 | I reject making the direction of causation axiomatic, since that takes too much for granted [Lewis] |
| Full Idea: One might stipulate that a cause must always precede its effect, but I reject this solution. It won't solve the problem of epiphenomena, it rejects a priori any backwards causation, and it trivializes defining time-direction through causation. | |
| From: David Lewis (Causation [1973], p.203) | |
| A reaction: [compressed] Not strong arguments, I would say. Maybe apparent causes are never epiphenomenal. Maybe backwards causation is impossible. Maybe we must use time to define causal direction, and not vice versa. |
| 10392 | It is just individious discrimination to pick out one cause and label it as 'the' cause [Lewis] |
| Full Idea: We sometimes single out one among all the causes of some event and call it 'the' cause. ..We may select the abnormal causes, or those under human control, or those we deem good or bad, or those we want to talk about. This is invidious discrimination. | |
| From: David Lewis (Causation [1973]) | |
| A reaction: This is the standard view expressed by Mill - presumably the obvious empiricist line. But if we specify 'the pre-conditions' for an event, we can't just mention ANY fact prior to the effect - there is obvious relevance. So why not for 'the' cause as well? |
| 8419 | The modern regularity view says a cause is a member of a minimal set of sufficient conditions [Lewis] |
| Full Idea: In present-day regularity analyses, a cause is defined (roughly) as any member of any minimal set of actual conditions that are jointly sufficient, given the laws, for the existence of the effect. | |
| From: David Lewis (Causation [1973], p.193) | |
| A reaction: This is the view Lewis is about to reject. It seem to summarise the essence of the Mackie INUS theory. This account would make the presence of oxygen a cause of almost every human event. |
| 8421 | Regularity analyses could make c an effect of e, or an epiphenomenon, or inefficacious, or pre-empted [Lewis] |
| Full Idea: In the regularity analysis of causes, instead of c causing e, c might turn out to be an effect of e, or an epiphenomenon, or an inefficacious effect of a genuine cause, or a pre-empted cause (by some other cause) of e. | |
| From: David Lewis (Causation [1973], p.194) | |
| A reaction: These are Lewis's reasons for rejecting the general regularity account, in favour of his own particular counterfactual account. It is unlikely that c would be regularly pre-empted or epiphenomenal. If we build time's direction in, it won't be an effect. |
| 17525 | The counterfactual view says causes are necessary (rather than sufficient) for their effects [Lewis, by Bird] |
| Full Idea: The Humean idea, developed by Lewis, is that rather than being sufficient for their effects, causes are (counterfactual) necessary for their effects. | |
| From: report of David Lewis (Causation [1973]) by Alexander Bird - Causation and the Manifestation of Powers p.162 |
| 17524 | Lewis has basic causation, counterfactuals, and a general ancestral (thus handling pre-emption) [Lewis, by Bird] |
| Full Idea: Lewis's basic account has a basic causal relation, counterfactual dependence, and the general causal relation is the ancestral of this basic one. ...This is motivated by counterfactual dependence failing to be general because of the pre-emption problem. | |
| From: report of David Lewis (Causation [1973]) by Alexander Bird - Causation and the Manifestation of Powers p.161 | |
| A reaction: It is so nice when you struggle for ages with a topic, and then some clever person summarises it clearly for you. |
| 8397 | Counterfactual causation implies all laws are causal, which they aren't [Tooley on Lewis] |
| Full Idea: Some counterfactuals are based on non-causal laws, such as Newton's Third Law of Motion. 'If no force one way, then no force the other'. Lewis's counterfactual analysis implies that one force causes the other, which is not the case. | |
| From: comment on David Lewis (Causation [1973]) by Michael Tooley - Causation and Supervenience 5.2 | |
| A reaction: So what exactly does 'cause' my punt to move forwards? Basing causal laws on counterfactual claims looks to me like putting the cart before the horse. |
| 8423 | My counterfactual analysis applies to particular cases, not generalisations [Lewis] |
| Full Idea: My (counterfactual) analysis is meant to apply to causation in particular cases; it is not an analysis of causal generalizations. Those presumably quantify over particulars, but it is hard to match natural language to the quantifiers. | |
| From: David Lewis (Causation [1973], p.195) | |
| A reaction: What authority could you have for asserting a counterfactual claim, if you only had one observation? Isn't the counterfactual claim the hallmark of a generalisation? For one case, 'if not-c, then not-e' is just a speculation. |
| 8426 | One event causes another iff there is a causal chain from first to second [Lewis] |
| Full Idea: One event is the cause of another iff there exists a causal chain leading from the first to the second. | |
| From: David Lewis (Causation [1973], p.200) | |
| A reaction: It will be necessary to both explain and identify a 'chain'. Some chains are extremely tenuous (Alexander could stop a barrel of beer). Go back a hundred years, and the cause of any present event is everything back then. |
| 4795 | Lewis's account of counterfactuals is fine if we know what a law of nature is, but it won't explain the latter [Cohen,LJ on Lewis] |
| Full Idea: Lewis can elucidate the logic of counterfactuals on the assumption that you are not at all puzzled about what a law of nature is. But if you are puzzled about this, it cannot contribute anything towards resolving your puzzlement. | |
| From: comment on David Lewis (Causation [1973]) by L. Jonathan Cohen - The Problem of Natural Laws p.219 | |
| A reaction: This seems like a penetrating remark. The counterfactual theory is wrong, partly because it is epistemological instead of ontological, and partly because it refuses to face the really difficult problem, of what is going on out there. |
| 13713 | Quine holds time to be 'space-like': past objects are as real as spatially remote ones [Quine, by Sider] |
| Full Idea: Quine's view is that time is 'space-like'. Past objects are as real as present ones; they're just temporally distant, just as spatially distant objects are just as real as the ones around here. | |
| From: report of Willard Quine (Mr Strawson on Logical Theory [1953]) by Theodore Sider - Logic for Philosophy 7.3.1 | |
| A reaction: Something is a wrong with a view that says that a long-dead person is just as real as one currently living. Death is rather more than travelling to a distant place. Arthur Prior responded to Quine by saying 'tense operators' are inescapable. |