Full Idea
When a set is finite, we can prove it has a choice function (∀x x∈A → f(x)∈A), but we need an axiom when A is infinite and the members opaque. From infinite shoes we can pick a left one, but from socks we need the axiom of choice.
Gist of Idea
We can choose from finite and evident sets, but not from infinite opaque ones
Source
William D. Hart (The Evolution of Logic [2010], 1)
Book Reference
Hart,W.D.: 'The Evolution of Logic' [CUP 2010], p.27
A Reaction
The socks example in from Russell 1919:126.