29 ideas
| 14001 | People who use science to make philosophical points don't realise how philosophical science is [Markosian] |
| Full Idea: When people give arguments from scientific theories to philosophical conclusions, there is usually a good deal of philosophy built into the relevant scientific theories. | |
| From: Ned Markosian (A Defense of Presentism [2004], 3.9) | |
| A reaction: I love this remark, being thoroughly fed up with knowledgeable scientists who are naïve about philosophy, and think their current theory demolishes long-lasting aporiai. They are up to their necks in philosophy. |
| 13991 | Presentism has the problem that if Socrates ceases to exist, so do propositions about him [Markosian] |
| Full Idea: Presentism has a problem with singular propositions about non-present objects. ...When Socrates popped out of existence, according to Presentism, all those singular propositions about him also popped out of existence. | |
| From: Ned Markosian (A Defense of Presentism [2004], 2.1) | |
| A reaction: He seems to treat propositions in a Russellian way, as things which exist independently of thinkers, which I struggle to grasp. Markosian offers various strategies for this [§3.5]. |
| 7791 | The simplest of the logics based on possible worlds is Lewis's S5 [Lewis,CI, by Girle] |
| Full Idea: C.I.Lewis constructed five axiomatic systems of modal logic, and named them S1 to S5. It turns out that the simplest of the logics based on possible worlds is the same as Lewis's S5. | |
| From: report of C.I. Lewis (works [1935]) by Rod Girle - Modal Logics and Philosophy 2.1 | |
| A reaction: Nathan Salmon ('Reference and Essence' 2nd ed) claims (on p.xvii) that "the correct modal logic is weaker than S5 and weaker even than S4". Which is the greater virtue, simplicity or weakness? |
| 9358 | There are several logics, none of which will ever derive falsehoods from truth [Lewis,CI] |
| Full Idea: The fact is that there are several logics, markedly different, each self-consistent in its own terms and such that whoever, using it, avoids false premises, will never reach a false conclusion. | |
| From: C.I. Lewis (A Pragmatic Conception of the A Priori [1923], p.366) | |
| A reaction: As the man who invented modal logic in five different versions, he speaks with some authority. Logicians now debate which version is the best, so how could that be decided? You could avoid false conclusions by never reasoning at all. |
| 9357 | Excluded middle is just our preference for a simplified dichotomy in experience [Lewis,CI] |
| Full Idea: The law of excluded middle formulates our decision that whatever is not designated by a certain term shall be designated by its negative. It declares our purpose to make a complete dichotomy of experience, ..which is only our penchant for simplicity. | |
| From: C.I. Lewis (A Pragmatic Conception of the A Priori [1923], p.365) | |
| A reaction: I find this view quite appealing. 'Look, it's either F or it isn't!' is a dogmatic attitude which irritates a lot of people, and appears to be dispensible. Intuitionists in mathematics dispense with the principle, and vagueness threatens it. |
| 9364 | Names represent a uniformity in experience, or they name nothing [Lewis,CI] |
| Full Idea: A name must represent some uniformity in experience or it names nothing. | |
| From: C.I. Lewis (A Pragmatic Conception of the A Priori [1923], p.368) | |
| A reaction: I like this because, in the quintessentially linguistic debate about the exact logical role of names, it reminds us that names arise because of the way reality is; they are not sui generis private games for logicians. |
| 11002 | Equating necessity with informal provability is the S4 conception of necessity [Lewis,CI, by Read] |
| Full Idea: C.I.Lewis's S4 system develops a sense of necessity as 'provability' in some fairly informal sense. | |
| From: report of C.I. Lewis (works [1935]) by Stephen Read - Thinking About Logic Ch. 4 |
| 9362 | Necessary truths are those we will maintain no matter what [Lewis,CI] |
| Full Idea: Those laws and those laws only have necessary truth which we are prepared to maintain, no matter what. | |
| From: C.I. Lewis (A Pragmatic Conception of the A Priori [1923], p.367) | |
| A reaction: This bold and simple claim has famously been torpedoed by a well-known counterexample - that virtually every human being will cling on to the proposition "dogs have at some time existed" no matter what, but it clearly isn't a necessary truth. |
| 7803 | Modal logic began with translation difficulties for 'If...then' [Lewis,CI, by Girle] |
| Full Idea: C.I.Lewis began his groundbreaking work in modal logic because he was concerned about the unreliability of the material conditional as a translation of 'If ... then' conditionals. | |
| From: report of C.I. Lewis (Symbolic Logic (with Langford) [1932]) by Rod Girle - Modal Logics and Philosophy 12.3 | |
| A reaction: Compare 'if this is square then it has four corners' with 'if it rains then our afternoon is ruined'. Different modalities seem to be involved. We even find that 'a square has four corners' will be materially implied if it rains! |
| 14002 | Possible worlds must be abstract, because two qualitatively identical worlds are just one world [Markosian] |
| Full Idea: Possible worlds are just abstract objects that play a certain role in philosophers' talk about modality. They are ways things could be. That's why there are no two abstract possible worlds which are qualitatively identical. They count as one world. | |
| From: Ned Markosian (A Defense of Presentism [2004], 3.10) | |
| A reaction: Brilliant! This looks like the best distinction between concrete and abstract. If two concreta are identical they remain two; if two abstracta are identical they are one (like numbers, or logical connectives with the same truth table). |
| 9365 | We can maintain a priori principles come what may, but we can also change them [Lewis,CI] |
| Full Idea: The a priori contains principles which can be maintained in the face of all experience, representing the initiative of the mind. But they are subject to alteration on pragmatic grounds, if expanding experience shows their intellectual infelicity. | |
| From: C.I. Lewis (A Pragmatic Conception of the A Priori [1923], p.373) | |
| A reaction: [compressed] This simply IS Quine's famous 'web of belief' picture, showing how firmly Quine is in the pragmatist tradition. Lewis treats a priori principles as a pragmatic toolkit, which can be refined to be more effective. Not implausible... |
| 21500 | We rely on memory for empirical beliefs because they mutually support one another [Lewis,CI] |
| Full Idea: When the whole range of empirical beliefs is taken into account, all of them more or less dependent on memorial knowledge, we find that those which are most credible can be assured by their mutual support, or 'congruence'. | |
| From: C.I. Lewis (An Analysis of Knowledge and Valuation [1946], 334), quoted by Erik J. Olsson - Against Coherence 3.1 | |
| A reaction: Lewis may be over-confident about this, and is duly attacked by Olson, but it seems to me roughly correct. How do you assess whether some unusual element in your memory was a dream or a real experience? |
| 21501 | If we doubt memories we cannot assess our doubt, or what is being doubted [Lewis,CI] |
| Full Idea: To doubt our sense of past experience as founded in actuality, would be to lose any criterion by which either the doubt itself or what is doubted could be corroborated. | |
| From: C.I. Lewis (An Analysis of Knowledge and Valuation [1946], 358), quoted by Erik J. Olsson - Against Coherence 3.3.1 | |
| A reaction: Obviously scepticism about memory can come in degrees, but total rejection of short-term and clear memories looks like a non-starter. What could you put in its place? Hyper-rationalism? Even maths needs memory. |
| 6556 | If anything is to be probable, then something must be certain [Lewis,CI] |
| Full Idea: If anything is to be probable, then something must be certain. | |
| From: C.I. Lewis (An Analysis of Knowledge and Valuation [1946], 186), quoted by Robert Fogelin - Walking the Tightrope of Reason Intro | |
| A reaction: Lewis makes this comment when facing infinite regress problems. It is a very nice slogan for foundationalism, which embodies the slippery slope view. Personally I feel the emotional pull of foundations, but acknowledge the very strong doubts about them. |
| 21498 | Congruents assertions increase the probability of each individual assertion in the set [Lewis,CI] |
| Full Idea: A set of statements, or a set of supposed facts asserted, will be said to be congruent if and only if they are so related that the antecedent probability of any one of them will be increased if the remainder of the set can be assumed as given premises. | |
| From: C.I. Lewis (An Analysis of Knowledge and Valuation [1946], 338), quoted by Erik J. Olsson - Against Coherence 2.2 | |
| A reaction: This thesis is vigorously attacked by Erik Olson, who works through the probability calculations. There seems an obvious problem without that. How else do you assess 'congruence', other than by evidence of mutual strengthening? |
| 22352 | Out of more than a hundred planets, Earth is the only one with the idea of free will [Vonnegut] |
| Full Idea: I wouldn’t have any idea what was meant by ‘free will'. I’ve visited thirty-one inhabited planets in the universe, and studied reports on one hundred more. Only on Earth is there any talk of free will. | |
| From: Kurt Vonnegut (Slaughterhouse Five [1969], Ch.4) | |
| A reaction: Spoken by the ambassador from the planet Tralfamadore. Possibly the greatest put down of a philosophical idea since Diogenes responded to Plato's definition of a man. I think free will is a non-idea. It is non-sensical, and doesn't exist. |
| 5828 | Extension is the class of things, intension is the correct definition of the thing, and intension determines extension [Lewis,CI] |
| Full Idea: "The denotation or extension of a term is the class of all actual or existent things which the term correctly applies to or names; the connotation or intension of a term is delimited by any correct definition of it." ..And intension determines extension. | |
| From: C.I. Lewis (An Analysis of Knowledge and Valuation [1946]), quoted by Stephen P. Schwartz - Intro to Naming,Necessity and Natural Kinds §II | |
| A reaction: The last part is one of the big ideas in philosophy of language, which was rejected by Putnam and co. If you were to reverse the slogan, though, (to extension determines intension) how would you identify the members of the extension? |
| 9361 | We have to separate the mathematical from physical phenomena by abstraction [Lewis,CI] |
| Full Idea: Physical processes present us with phenomena in which the purely mathematical has to be separated out by abstraction. | |
| From: C.I. Lewis (A Pragmatic Conception of the A Priori [1923], p.367) | |
| A reaction: This is the father of modal logic endorsing traditional abstractionism, it seems. He is also, though, endorsing the view that a priori knowledge is created by us, with pragmatic ends in view. |
| 14000 | 'Grabby' truth conditions first select their object, unlike 'searchy' truth conditions [Markosian] |
| Full Idea: We can talk of 'grabby' truth conditions (where an object is grabbed before predication) and 'searchy' truth conditions (where the object is included in what is being asserted). | |
| From: Ned Markosian (A Defense of Presentism [2004], 3.8) | |
| A reaction: [He credits Tom Ryckman with the terminology] I am inclined to think that the whole of language is 'searchy', even when it appears to be blatantly 'grabby'. Even ostensive reference is an act of hope rather than certainty. |
| 9363 | Science seeks classification which will discover laws, essences, and predictions [Lewis,CI] |
| Full Idea: The scientific search is for such classification as will make it possible to correlate appearance and behaviour, to discover law, to penetrate to the "essential nature" of things in order that behaviour may become predictable. | |
| From: C.I. Lewis (A Pragmatic Conception of the A Priori [1923], p.368) | |
| A reaction: Modern scientific essentialists no longer invoke scare quotes, and I think we should talk of the search for the 'mechanisms' which explain behaviour, but Lewis seems to have been sixty years ahead of his time. |
| 13990 | Presentism is the view that only present objects exist [Markosian] |
| Full Idea: According to Presentism, if we were to make an accurate list of all the things that exist (within the range of our most unrestricted quantifiers) there would not be a single non-present object on the list. | |
| From: Ned Markosian (A Defense of Presentism [2004], 1) | |
| A reaction: An immediate problem that needs examing is what constitutes an 'object'. It had better not range over time (like an journey). It would be hard to fit a description like 'the oldest man in England'. |
| 13992 | Presentism says if objects don't exist now, we can't have attitudes to them or relations with them [Markosian] |
| Full Idea: If there are no non-present objects (according to Presentism), then no one can now stand in any relation to any non-present object. You cannot now 'admire' Socrates, and no present event has a causal relation to Washington crossing the Delaware. | |
| From: Ned Markosian (A Defense of Presentism [2004], 2.2) | |
| A reaction: You can have an overlapping causal chain that gets you back to Washington, and a causal chain can connect Socrates to our thoughts about him (as in baptismal reference). A simple reply needs an 'overlap' though. |
| 13994 | Presentism seems to entail that we cannot talk about other times [Markosian] |
| Full Idea: It is very natural to talk about times, ...but Presentism seems to entail that we never say anything about any such times. | |
| From: Ned Markosian (A Defense of Presentism [2004], 2.4) | |
| A reaction: I'm beginning to think that Markosian is in the grips of a false notion of proposition, as something that exists independently of thinkers, and is entailed by the facts and objects of reality. This is not what language does. |
| 13995 | Serious Presentism says things must exist to have relations and properties; Unrestricted version denies this [Markosian] |
| Full Idea: Mark Hinchliff distinguishes between 'Serious' Presentism (objects only have relations and properties when they exist) and 'Unrestricted' Presentism (objects can have relations and properties even when they don't exist). | |
| From: Ned Markosian (A Defense of Presentism [2004], 3.1) | |
| A reaction: [Hinchliff 1996:124-6] Markosian votes for the Serious version, as being the only true Presentism. I think he is muddling language and reality, predicates and properties. |
| 13996 | Maybe Presentists can refer to the haecceity of a thing, after the thing itself disappears [Markosian] |
| Full Idea: Some Presentists (such as Adams) believe that a haecceity (a property unique to some entity) continues to exist even after its object ceases to exist. A sentence about Socrates still expresses a proposition, about 'Socraticity'. | |
| From: Ned Markosian (A Defense of Presentism [2004], 3.4) | |
| A reaction: [Adams 1986] This is rather puzzling. In what sense could a haecceity 'exist' to be referred to? Existence, but not as we know it, Jim. This smacks of medieval theology. |
| 13997 | Maybe Presentists can paraphrase singular propositions about the past [Markosian] |
| Full Idea: Maybe Presentists can paraphrase singular propositions about the past, into purely general past- and future-tensed sentences. | |
| From: Ned Markosian (A Defense of Presentism [2004], 3.5) | |
| A reaction: I'm not clear why Markosian worries about singular propositions, but is happy with general ones. Surely the latter refer as much as the former to what doesn't exist? Markosian objects that the paraphrase has a different meaning. |
| 13993 | Special Relativity denies the absolute present which Presentism needs [Markosian] |
| Full Idea: The objection to Presentism from Special Relativity is this: 1) Relativity is true, 2) so there is no absolute simultaneity, 3) so there is no absolute presentness, but 4) Presentism entails absolute presentness, so 5) Presentism is false. | |
| From: Ned Markosian (A Defense of Presentism [2004], 3.9) | |
| A reaction: I don't accept this objection. There may be accounts that can give Relativity one present (Idea 12689-90). Maybe Einstein was too instrumentalist in his account. Maybe we can have Presentism with multiple present moments. |
| 13998 | Objects in the past, like Socrates, are more like imaginary objects than like remote spatial objects [Markosian] |
| Full Idea: Maybe putative non-present objects like Socrates have more in common with putative non-actual objects like Santa Claus than they have in common with objects located elsewhere in space, like Alpha Centauri. | |
| From: Ned Markosian (A Defense of Presentism [2004], 3.7) | |
| A reaction: We can see Alpha Centauri, so we need an example beyond some 'event horizon'. He credits Arthur Prior with this line of thought. He seems to me to drift towards a Descriptive Theory of Reference (shock!). Does the nature of reference change with death? |
| 13999 | People are mistaken when they think 'Socrates was a philosopher' says something [Markosian] |
| Full Idea: People sometimes think that 'Socrates was a philosopher' expresses something like a true, singular proposition about Socrates. They're making a mistake, but still, this explains why they think it is true. | |
| From: Ned Markosian (A Defense of Presentism [2004], 3.8) | |
| A reaction: A classic error theory, about our talk of the past. Personally I would say that the sentence really is true, and that needing a tangible object to refer to is a totally bogus requirement. 'I wonder if there are any scissors in the house?' |