Full Idea
A bare minimum of metaphysical belief about the self is found to be absolutely presupposed in the very idea of morality.
Gist of Idea
Morality requires a minimum commitment to the self
Source
Hastings Rashdall (Theory of Good and Evil [1907], II.III.I.4)
Book Reference
'The Existence of God', ed/tr. Hick,John [Macmillan 1964], p.146
A Reaction
This may not be true of virtue theory, where we could have a whole creature which lacked any sense of personhood, but yet had clear virtues and vices in its social functioning. Even if choices are central to morality, that might not need a self.