Full Idea
Moore tries to show that 'good' is indefinable by relying on a bad dictionary definition of 'definition'.
Gist of Idea
Moore tries to show that 'good' is indefinable, but doesn't understand what a definition is
Source
comment on G.E. Moore (Principia Ethica [1903]) by Alasdair MacIntyre - After Virtue: a Study in Moral Theory Ch.2
Book Reference
MacIntyre,Alasdair: 'After Virtue: a Study in Moral Theory' [Duckworth 1982], p.15
A Reaction
An interesting remark, with no further explanation offered. If Moore has this problem, then Plato had it too (see Idea 3032). I would have thought that any definition MacIntyre could offer would either be naturalistic, or tautological.
Related Idea
Idea 3032 I can form no notion of what the good is [Amphis]