Full Idea
Russell's solution (in the theory of types) consists of restricting the principle that every predicate has a set as its extension so that only meaningful predicates have sets as their extensions.
Gist of Idea
Russell's proposal was that only meaningful predicates have sets as their extensions
Source
report of Bertrand Russell (Introduction to Mathematical Philosophy [1919]) by Alex Orenstein - W.V. Quine Ch.3
Book Reference
Orenstein,Alex: 'W.V. Quine' [Princeton 2002], p.58
A Reaction
There might be a chicken-and-egg problem here. How do you decide the members of a set (apart from ostensively) without deciding the predicate(s) that combine them?