Full Idea
The grounding of a moral argument is ultimately in facts about human life.
Gist of Idea
Moral arguments are grounded in human facts
Source
Philippa Foot (Does Moral Subjectivism Rest on a Mistake? [1995], p.207)
Book Reference
Foot,Philippa: 'Moral Dilemmas' [OUP 2002], p.207
A Reaction
The best slogan I can find for summarising Foot's metaethics. The facts she refers to the basic human needs. She is right, and this almost bridges the fact-value divide (as long as you give a damn about human needs).