Full Idea
Moore incoherently combines his antinaturalism with the thesis that intrinsic-value properties are logically strongly supervenient on (or explanatorily reducible to) natural facts.
Gist of Idea
Moore's combination of antinaturalism with strong supervenience on the natural is incoherent
Source
comment on G.E. Moore (Principia Ethica [1903]) by Robert Hanna - Rationality and Logic Ch.1
Book Reference
Hanna,Robert: 'Rationality and Logic' [MIT 2006], p.2
A Reaction
I take this to be Moore fighting shy of the strongly Platonist view of values which his arguments all seemed to imply.