Full Idea
Only those action norms are valid to which all possibly affected persons could agree as participants in rational discourse.
Gist of Idea
Actions norms are only valid if everyone possibly affected is involved in the discourse
Source
Jürgen Habermas (Between Facts and Norms [1996], p.107), quoted by James Gordon Finlayson - Habermas Ch.6:79
Book Reference
Finlayson,James G.: 'Habermas' [OUP 2005], p.79
A Reaction
This remark stands somewhere between Kant and Rawls. The Holocaust stands behind Habermas's philosophy. The thought, I suppose, is that it would never have happened if everybody had been fully involved in the original discourse about it.