[T]he appropriate circumstantial perspective to take in an honest and open discussion of what ought to be done (never mind who it may be ‘up to’ to do it) is that of all parties influenceable by the discussion—which one presumes to include one’s interlocutors. This gives rise to an invisible (or unarticulated) ‘we’ in the superscripted position of all ought-judgments. The grain of sense in the saying ‘There’s no use crying over spilt milk’ is in its recommendation to plan for the future, taking it as fixed that the milk has been spilt. The same goes for the milk that will be freely spilt by others whose conduct cannot be influenced by us.
I. L. Humberstone, ‘Two Kinds of Agent-Relativity’, The Philosophical Quarterly, vol. 41, no. 163 (April, 1991), p.166