Full Idea
Asking whether the attitude that one has adopted is the right attitude comes down to asking whether one is prepared to stand by it.
Gist of Idea
A right attitude is just an attitude one is prepared to stand by
Source
A.J. Ayer (On the analysis of moral judgements [1949], p.244)
Book Reference
Ayer,A.J.: 'Philosophical Essays' [Macmillan 1965], p.244
A Reaction
I would have thought that someone who persisted in being ruthlessly selfish might nevertheless distinguish their behaviour from the grudging concession that the 'right' thing to do might be quite different.