Our disagreements on a societal level are much more complex, and can require a different response. One particularly pernicious form of disagreement arises when we not only disagree about individuals facts, as in Frank and Gita’s case, but also disagree about how best to form beliefs about those facts, that is, about how to gather and assess evidence in proper ways. This is deep disagreement, and it’s the form that most societal disagreements take. Understanding these disagreements will not inspire optimism about our ability to find consensus.
Generally, theorising about liberal democracy has focused largely on moral and political disagreements, while tacitly assuming that there would be no important factual disagreements to consider. It has been taken for granted that we would eventually agree about the facts, and the democratic processes would concern how we should adjudicate our differences in values and preferences. But this assumption is no longer adequate, if it ever was.