Full Idea
The iterative conception of sets does not tell us how far to iterate, and so we must start with an Axiom of Infinity. It also presupposes the notion of 'transfinite iteration'.
Gist of Idea
The iterative conception needs the Axiom of Infinity, to show how far we can iterate
Source
Shaughan Lavine (Understanding the Infinite [1994], V.5)
Book Reference
Lavine,Shaughan: 'Understanding the Infinite' [Harvard 1994], p.148