Ideas from 'A Pragmatic Conception of the A Priori' by C.I. Lewis [1923], by Theme Structure

[found in 'Pragmatism - The Classic Writings' by Peirce,James,Dewey etc (ed/tr Thayer,H.S.) [Hackett 1982,0-915145-37-5]].

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5. Theory of Logic / A. Overview of Logic / 1. Overview of Logic
There are several logics, none of which will ever derive falsehoods from truth
                        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.
5. Theory of Logic / D. Assumptions for Logic / 2. Excluded Middle
Excluded middle is just our preference for a simplified dichotomy in experience
                        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.
5. Theory of Logic / F. Referring in Logic / 1. Naming / a. Names
Names represent a uniformity in experience, or they name nothing
                        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.
10. Modality / A. Necessity / 11. Denial of Necessity
Necessary truths are those we will maintain no matter what
                        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.
12. Knowledge Sources / A. A Priori Knowledge / 7. A Priori from Convention
We can maintain a priori principles come what may, but we can also change them
                        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...
18. Thought / E. Abstraction / 2. Abstracta by Selection
We have to separate the mathematical from physical phenomena by abstraction
                        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.
26. Natural Theory / D. Laws of Nature / 8. Scientific Essentialism / a. Scientific essentialism
Science seeks classification which will discover laws, essences, and predictions
                        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.