  To defend the claim that disagreement about grounds is indeed possible, one would have to resist the assumption that, as a general matter, we can only share a subject matter by sharing truths that define it. Indeed Dworkin, anticipating that his examples of disagreement that appears to be about grounds would be reinterpreted by his critics as disagreement about social facts or about how to change the law, invited his critics not to rule out the possibility that disagreement might be more fundamental. He said that to think that disagreement about grounds is never possible, for the reason that to share a subject matter we must share criteria that define it, is a philosophical prejudice: he called the prejudice “the semantic sting” (see Dworkin 1986).