As I have noted above, Gregory wants to claim that we must consider medieval Christendom a failure when we judge it in accordance with its own internal criteria. Now, when Gregory examines the modern predicament of liberal and hyperpluralist society today, he says that he is only interested in applying the same technique; that is, he is supposed to apply an internal criterion for failure here too. The problem is that he does nothing of the kind. For, according to Gregory himself, it is one of the distinctive features of secular society in the modern West that it has abandoned the expectation of a comprehensive and shared metaphysics that was a governing principle of medieval Christendom. This is not a technical point. According to Gregory, the social ideal of caritas could make sense only within a teleological conception of the universe according to which everyone and everything was thought to be the creation of a benevolent God whose goodness was the object of veneration and the paradigm for one’s own conduct. Strong conformity was an intrinsic part of that ideal. But one of the distinctive features of modern liberal culture is that it seems to be abandoning the expectation that its members share any single metaphysical vision. In a modern liberal society, the strong conformity that was a requirement in medieval Christendom no longer plays a determining role.
Gregory seems to think this turn away from strong conformity is a bad thing because it signals our loss of any substantive notion of the good. Bereft of this normative principle we find ourselves thrown us back upon our own meager and subjective resources for deciding upon doing whatever it is we wish to do. Hyperpluralism is the inevitable result. Now, most readers will recognize that this is a slippery slope argument of the most drastic kind: It upholds one true standard for things going as they should, and when that standard is abandoned we are meant to conclude that nothing could possibly go right. The slope in this case is not just slippery, it is frictionless.
The real difficulty with this argument, however, is that it imports from medieval Christendom a criterion that has little place in modern liberal notions of social membership. Most of us today simply do not adhere to the ideal of a holistic social order and we no longer expect or even value the ideal of a society that grounds itself in a single metaphysical conception of the cosmic whole. In fact, many liberal theorists would say that it was the precisely the violence of religious persecution and religious conflict in previous centuries that helped to bring the idea of strong conformity into discredit. We want to arrange things in such a way that when our ideals are not shared we are less tempted than our medieval predecessors to resort to coercion. The ideal of a modern liberal regime (an ideal we have certainly failed to realize to any adequate degree) is one in which certain norms of cooperation can be endorsed by nearly all participants irrespective of their metaphysical commitments.