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Single Idea 18165

[filed under theme 6. Mathematics / C. Sources of Mathematics / 6. Logicism / a. Early logicism ]

Full Idea

I hold that my Basic Law V is a law of pure logic.

Gist of Idea

My Basic Law V is a law of pure logic

Source

Gottlob Frege (Grundgesetze der Arithmetik 1 (Basic Laws) [1893], p.4), quoted by Penelope Maddy - Naturalism in Mathematics I.1

Book Ref

Maddy,Penelope: 'Naturalism in Mathematics' [OUP 2000], p.6


A Reaction

This is, of course, the notorious law which fell foul of Russell's Paradox. It is said to be pure logic, even though it refers to things that are F and things that are G.


The 9 ideas from 'Grundgesetze der Arithmetik 1 (Basic Laws)'

Frege considered definite descriptions to be genuine singular terms [Frege, by Fitting/Mendelsohn]
Frege defined number in terms of extensions of concepts, but needed Basic Law V to explain extensions [Frege, by Hale/Wright]
Frege ignored Cantor's warning that a cardinal set is not just a concept-extension [Tait on Frege]
A concept is a function mapping objects onto truth-values, if they fall under the concept [Frege, by Dummett]
Frege took the study of concepts to be part of logic [Frege, by Shapiro]
Contradiction arises from Frege's substitutional account of second-order quantification [Dummett on Frege]
Real numbers are ratios of quantities, such as lengths or masses [Frege]
We can't prove everything, but we can spell out the unproved, so that foundations are clear [Frege]
My Basic Law V is a law of pure logic [Frege]