Full Idea
Eventually set theory will have to be either naturalised or rejected, if a thoroughgoing physicalism is to be maintained.
Gist of Idea
Physicalism requires the naturalisation or rejection of set theory
Source
William Lycan (Consciousness [1987], 8.4)
Book Reference
Lycan,William G.: 'Consciousness' [MIT 1995], p.90
A Reaction
Personally I regard Platonism as a form of naturalism (though a rather bold and dramatic one). The central issue seems to be the ability of the human main/brain to form 'abstract' notions about the physical world in which it lives.