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Single Idea 18170

[filed under theme 4. Formal Logic / F. Set Theory ST / 4. Axioms for Sets / p. Axiom of Reducibility ]

Full Idea

The Axiom of Reducibility is self-effacing: if it is true, the ramification it is meant to cope with was pointless to begin with.

Gist of Idea

The Axiom of Reducibility is self-effacing: if true, it isn't needed

Source

Willard Quine (Introduction to Russell's Theory of Types [1967], p.152), quoted by Penelope Maddy - Naturalism in Mathematics I.1

Book Ref

Maddy,Penelope: 'Naturalism in Mathematics' [OUP 2000], p.12


A Reaction

Maddy says the rejection of Reducibility collapsed the ramified theory of types into the simple theory.


The 10 ideas with the same theme [outdated axiom saying functions reduce to basics]:

Reducibility: a family of functions is equivalent to a single type of function [Russell]
Russell saw Reducibility as legitimate for reducing classes to logic [Linsky,B on Russell/Whitehead]
Axiom of Reducibility: there is always a function of the lowest possible order in a given level [Russell, by Bostock]
Reducibility: to every non-elementary function there is an equivalent elementary function [Ramsey]
In simple type theory the axiom of Separation is better than Reducibility [Gödel, by Linsky,B]
The Axiom of Reducibility is self-effacing: if true, it isn't needed [Quine]
Reducibility undermines type ramification, and is committed to the existence of functions [Quine, by Linsky,B]
Axiom of Reducibility: propositional functions are extensionally predicative [Maddy]
Reducibility says any impredicative function has an appropriate predicative replacement [Linsky,B]
The Axiom of Reducibility made impredicative definitions possible [George/Velleman]