Peter E. Gordon on Brad Gregory’s The Unintended Reformation in The Immanent Frame:
[T]he characteristic stance of liberal society toward substantive metaphysical commitments is not dogmatic rejectionism but epistemic humility. This is why John Rawls famously characterized his own theory of justice “political, not metaphysical.” And for similar reasons Jürgen Habermas recommends that we build a society on the basis of nothing more than intersubjective argumentation itself and without recourse to metaphysics. What he calls “post-metaphysical thinking” does not presume that all members of a society surrender their respective religious beliefs. It only suggests that, given the current pluralism of our crowded world, we can no longer afford the arrogant expectation that others will conform to the metaphysical commitments we happen to hold and that we should no longer make such conformity a requirement for social inclusion.
Gregory does not judge the liberal ideal according to its own internal criteria. He does not see the liberal ideal as viable chiefly because he does not think that there can be any viable alternative to the substantive conception of normativity that helped to underwrite the medieval Christian world. He states this with the boldest confidence: “Once the metaphysical basis of an ethics of the good has been jettisoned, nothing remains in principle [my emphasis] but the human will and its desires protected by the state” (189). We are protected from this nihilistic outcome today only thanks to the surviving metaphysical beliefs of “ancient and medieval Christianity” and “secular adaptations to them, in addition to similar beliefs and values from peoples of other religious traditions and parts of the world.” Absent these persistent resources of the world’s metaphysical traditions, “human life in Europe and North America would be either unbearably oppressive, unbearably chaotic, or both.”
I fear that this is not a good argument. A great many philosophers have disagreed and continue to disagree as to what sort of meta-ethical commitments we require for our ethical beliefs. It is surely a bit grand and obviously too soon to conclude that if one type of meta-ethical commitment is cast aside everything must go to hell in a handbasket. And here is the point. Why should there be only one species of meta-ethics that somehow remains our permanent ideal?
More here.