In a 2008 essay in The Princeton Seminary Bulletin (since reprinted elsewhere), Oliver O’Donovan offers “Reflections on Pluralism.” He wonders at the outset why we add an “ism” to the word, and suggests that understanding “difference as plurality” reflects an anxiety about difference. Not all difference creates anxiety, but only those differences of “practical principle” that lead different subcultures to “act on contrary assumptions and pursue divergent courses in their relations with each other.” Pluralism treats these differences of practical principle as “a foundational problem, given in the very nature of social inaction.”
Pluralism “copes” with this danger by distinguishing ” different orders of practical principles to govern conduct.” In addition to our community-specific principles, we must adopt a set of ” second-order principles ” to govern our interactions across tribal boundaries. This is to be “a regime of practical thinking detached from all fundamental principles of action,” in short a “public reason.”
More on O’Donovan’s article later, and thanks to Ken Myers for pointing me to it.