15 ideas
| 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. |
| 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. |
| 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. |
| 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. |
| 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. |
| 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. |
| 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. |
| 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... |
| 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. |
| 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). |
| 23395 | Mohists desire wealth, population and social order as the best consequences [Mozi, by Norden] |
| Full Idea: The consequentialist Mohists give a fairly objective characterisation of benefits as wealth, populousness, and social order, and harm as poverty, depopulation, and social chaos. | |
| From: report of Mozi (The Mozi [c.440 BCE]) by Bryan van Norden - Intro to Classical Chinese Philosophy 4.I | |
| A reaction: That is a formula favoured by many authoritarian leaders in modern times. |
| 23394 | If people regarded other states as they did their own, they would never attack them [Mozi] |
| Full Idea: If people regarded other people's states in the same way that they regard their own, who then would incite their own state to attack that of another? | |
| From: Mozi (The Mozi [c.440 BCE], 16), quoted by Bryan van Norden - Intro to Classical Chinese Philosophy 4.I | |
| A reaction: A nice case of the application of golden rule thinking to states, instead of to individuals. I can't see Putin (in 2022) being impressed by 'how would you like it if another country invaded Russia?'. The Golden Rule is an analogy argument. |
| 23396 | Mozi condemns partiality, which is the cause of all the great harms in the world [Mozi] |
| Full Idea: It is those who are partial in their dealings with others who are the real cause of all the great harms in the world. That is why our teacher Mozi says 'I condemn partiality'. | |
| From: Mozi (The Mozi [c.440 BCE], 16), quoted by Bryan van Norden - Intro to Classical Chinese Philosophy 4.II | |
| A reaction: This is morality as the rule of law, rather than as the result of human affections. He is on the same wavelength as Kant. Mozi was criticising Confucius, who favoured family over strangers. |
| 23397 | Those who are against impartiality still prefer impartial protectors [Mozi] |
| Full Idea: Even though one may not advocate impartiality, one would certainly want to entrust one's family to the person who is impartial. | |
| From: Mozi (The Mozi [c.440 BCE], 16), quoted by Bryan van Norden - Intro to Classical Chinese Philosophy 4.II | |
| A reaction: In the modern world his example would be the police, so he effectively he wants the impartiality of the law. But who wants legal impartiality within the affairs of a family? |
| 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. |