Full Idea
If we can make judgements about how we should live even after stepping outside of ourselves, they will provide the material for moral theory.
Gist of Idea
If we can decide how to live after stepping outside of ourselves, we have the basis of a moral theory
Source
Thomas Nagel (The View from Nowhere [1986], VIII.1)
Book Reference
Nagel,Thomas: 'The View from Nowhere' [OUP 1989], p.138