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Single Idea 13013

[filed under theme 4. Formal Logic / F. Set Theory ST / 4. Axioms for Sets / b. Axiom of Extensionality I ]

Full Idea

Most writers agree that if any sense can be made of the distinction between analytic and synthetic, then the Axiom of Extensionality should be counted as analytic.

Gist of Idea

The Axiom of Extensionality seems to be analytic

Source

Penelope Maddy (Believing the Axioms I [1988], §1.1)

Book Ref

-: 'Journal of Symbolic Logic' [-], p.484


A Reaction

[Boolos is the source of the idea] In other words Extensionality is not worth discussing, because it simply tells you what the world 'set' means, and there is no room for discussion about that. The set/class called 'humans' varies in size.


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]