more on this theme     |     more from this thinker


Single Idea 13025

[filed under theme 4. Formal Logic / F. Set Theory ST / 4. Axioms for Sets / j. Axiom of Choice IX ]

Full Idea

Resistance to the Axiom of Choice centred on opposition between existence and construction. Modern set theory thrives on a realistic approach which says the choice set exists, regardless of whether it can be defined, constructed, or given by a rule.

Gist of Idea

Modern views say the Choice set exists, even if it can't be constructed

Source

Penelope Maddy (Believing the Axioms I [1988], §1.7)

Book Ref

-: 'Journal of Symbolic Logic' [-], p.488


A Reaction

This seems to be a key case for the ontology that lies at the heart of theory. Choice seems to be an invaluable tool for proofs, so it won't go away, so admit it to the ontology. Hm. So the tools of thought have existence?


The 11 ideas from 'Believing the Axioms I'

New axioms are being sought, to determine the size of the continuum [Maddy]
The Axiom of Extensionality seems to be analytic [Maddy]
Extensional sets are clearer, simpler, unique and expressive [Maddy]
The Iterative Conception says everything appears at a stage, derived from the preceding appearances [Maddy]
Limitation of Size is a vague intuition that over-large sets may generate paradoxes [Maddy]
The Axiom of Infinity states Cantor's breakthrough that launched modern mathematics [Maddy]
Infinite sets are essential for giving an account of the real numbers [Maddy]
The Power Set Axiom is needed for, and supported by, accounts of the continuum [Maddy]
Efforts to prove the Axiom of Choice have failed [Maddy]
Modern views say the Choice set exists, even if it can't be constructed [Maddy]
A large array of theorems depend on the Axiom of Choice [Maddy]