  Whether or not the argument for (U) goes through, Habermas's discourse ethics depends on some very strong assumptions about the capacity of persons for moral dialogue. Given that his discourse theory in general, and thus (U) in particular, rests on counterfactual idealizations, one might be tempted to regard (U) as a hypothetical thought experiment, analogous to what we find in other neo-Kantian or contractualist theories like those of John Rawls and T. M. Scanlon. To some extent this is correct: to regard a moral norm as valid, one must presume it would hold up in a fully inclusive and reasonable discourse. But Habermas takes a further step, insisting that (U) is a principle of real discourse: an individual's moral judgment counts as fully reasonable only if it issues from participation in actual discourse with all those affected. Moreover, (U) requires not simply that one seek the input of others in forming one's conscience, but that one gain their reasonable agreement. 