4 ideas
8460 | Philosophers have given precise senses to deduction, probability, computability etc [Quine/Ullian] |
Full Idea: Successful explications (giving a precise sense to a term) have been found for the concepts of deduction, probability and computability, to name just three. | |
From: W Quine / J Ullian (The Web of Belief [1970], 65), quoted by Alex Orenstein - W.V. Quine Ch.3 | |
A reaction: Quine also cites the concept of an 'ordered pair'. Orenstein adds Tarski's definition of truth, Russell's definite descriptions, and the explication of existence in terms of quantifications. Cf. Idea 2958. |
17699 | Variables are auxiliary notions, and not part of the 'eternal' essence of logic [Schönfinkel] |
Full Idea: A variable in a proposition of logic ....has the status of a mere auxiliary notion that is really inappropriate to the constant, 'eternal' essence of the propositions of logic. | |
From: Moses Schönfinkel (Building Blocks of Mathematical Logic [1924], §1) | |
A reaction: He presumably thinks that what the variables stand for (and he mentions 'argument places' and 'operators') will be included in the essence. My attention was caught by the thought that he takes logic to have an essence. |
12427 | All of mathematics is properties of the whole numbers [Kronecker] |
Full Idea: All the results of significant mathematical research must ultimately be expressible in the simple forms of properties of whole numbers. | |
From: Leopold Kronecker (works [1885], Vol 3/274), quoted by Philip Kitcher - The Nature of Mathematical Knowledge 09.5 | |
A reaction: I've always liked Kronecker's line, but I'm beginning to realise that his use of the word 'number' is simply out-of-date. Natural numbers have a special status, but not sufficient to support this claim. |
10091 | God made the integers, all the rest is the work of man [Kronecker] |
Full Idea: God made the integers, all the rest is the work of man. | |
From: Leopold Kronecker (works [1885]), quoted by A.George / D.J.Velleman - Philosophies of Mathematics Intro | |
A reaction: This famous remark was first quoted in Kronecker's obituary. A response to Dedekind, it seems. See Idea 10090. Did he really mean that negative numbers were the work of God? We took a long time to spot them. |