The New York Times' resident intellectual, Stanley Fish the question of "public reason" or "secular reason." This is the classical liberal notion which underlies distinctions between church and state. Whatever a public agent does, the distinction goes, it must be justified by secular–i.e., non-religious–reasons.
As you might have guessed, Fish will have none of this. His sole reason (at least his sole intelligible reason) is that the notion of "secular value" is some kind of contradiction. All values are religious. And since all morality (and hence all moral action) has to do with values, ergo ipso fatso. He writes:
Nevertheless, Smith observes, the self-impoverished discourse of secular reason does in fact produce judgments, formulate and defend agendas, and speak in a normative vocabulary. How is this managed? By “smuggling,” Smith answers.
. . . the secular vocabulary within which public discourse is constrained today is insufficient to convey our full set of normative convictions and commitments. We manage to debate normative matters anyway — but only by smuggling in notions that are formally inadmissible, and hence that cannot be openly acknowledged or adverted to.
The notions we must smuggle in, according to Smith, include “notions about a purposive cosmos, or a teleological nature stocked with Aristotelian ‘final causes’ or a providential design,” all banished from secular discourse because they stipulate truth and value in advance rather than waiting for them to be revealed by the outcomes of rational calculation. But if secular discourse needs notions like these to have a direction — to even get started — “we have little choice except to smuggle [them] into the conversations — to introduce them incognito under some sort of secular disguise.”
And how do we do that? Well, one way is to invoke secular concepts like freedom and equality — concepts sufficiently general to escape the taint of partisan or religious affiliation — and claim that your argument follows from them. But, Smith points out (following Peter Westen and others), freedom and equality — and we might add justice, fairness and impartiality — are empty abstractions. Nothing follows from them until we have answered questions like “fairness in relation to what standard?” or “equality with respect to what measures?” — for only then will they have content enough to guide deliberation.
That content, however, will always come from the suspect realm of contested substantive values. Is fairness to be extended to everyone or only to those with certain credentials (of citizenship, education, longevity, etc.)? Is it equality of opportunity or equality of results (the distinction on which affirmative action debates turn)? Only when these matters have been settled can the abstractions do any work, and the abstractions, in and of themselves, cannot settle them. Indeed, concepts like fairness and equality are normatively useless, except as rhetorical ornaments, until they are filled in by some partisan or ideological or theological perspective, precisely the perspectives secular reason has forsworn. Therefore, Smith concludes, “conversations in the secular cage could not proceed very far without smuggling.”
The move there between the last two paragraphs is the suspect one. Unless there is a definitional necessity to the "always" there, I think there there is ample evidence that it need not be the case. Perhaps one might, to cite the obvious objection, claim that only an entirely abstract conception of justice can be the only satisfactory one–precisely because it is emptied of partisan perspective.
Underlying this move is the notion that "normative" means "partisan, ideological, i.e., religious." I think that's hardly the case. Those things are instances of normativity, but they're not the only ones.