In a private correspondence, Yusef (of The Enlightenment Underground) suggested the term "a pragmatics of the multiple" for what I want to do here -- a term which I'm happy to accept!
The contrast I wish to draw is between a pragmatics of the multiple and the metaphysics of unity. The former not only allows for but insists on a multiplicity of ways of speaking with the further realization that different ways of speaking are different ways in which human needs, desires, interests, fears, and hopes are given voice -- that is, in which they take on a concrete and public existence in the on-going life and evolution of a culture. Since these multiple ways of speaking can be in conflict, as needs and desires and interests are in conflict, there arises an agonistic dimension to cultural life which cannot be entirely eliminated.
The latter, the metaphysics of unity, is the demand to locate the correct way of speaking -- the way of speaking that fits the world, which shows us how the world really is. Such a way of speaking would put an end to all social antagonisms by showing once and for all what is true and what is false in each sphere of discourse. The impulse or urge towards a metaphysics of unity was born, and not without good reason, in Plato's rejection of the Sophists and of Thucydides. Since then even if one does not embrace the Platonic solutions to the problems he poses, it was felt that one is obliged to formulate an alternative. Thus the panoply of metaphysical doctrines: Aristotelianism, Epicureanism, Stoicism, Neoplatonism, Christianity (Augustinianism, Thomism), Cartesianism, Spinozism, mechanism/materialism, idealism, phenomenalism, Hegelianism, Marxism, process metaphysics (Nietzsche, Whitehead, Dewey, de Chardin, Bergson), phenomenological ontology (Heidegger, Sartre, Merleau-Ponty). Each doctrine opposes all the others and sets itself up as the most fundamental or highest truth of all things.
In the science/religion debate as it unfolds before us today, the deadlock is exacerbated by an insistence on the metaphysics of unity. Thus it is asked - do science and religion both refer to "the same reality"? Do they thereby conflict? Or do they refer to different "aspects" of "the same reality"? Or is one merely bias, subjective, opinion, and the other alone describes things as they really (basically, deeply, fundamentally, ultimately) are?
The pragmatics of the multiple offers a way out of this impasse by recognizing the metaphysics of unity as itself simply one more way of speaking. (This is, in effect, Nietzsche's jujitsu move against Plato. Among Nietzsche's Anglophone readers, Rorty has been unusual in his appreciation of the full force of this move.) But the pragmatics of the multiple is not mere Rortyian "conversation" any more than it is Habermasian "discourse." On the one hand, conversation and discourse are decisive turning-points in the trajectory that leads from the apes to the Enlightenment. There is no return to a time before Plato and before the ethics of dialogue, contra Nietzsche and contra Heidegger -- nor would we want such a return. The moral revulsion one feels at the world described by Thucydides is indication enough of that.
Thus a pragmatics of the multiple is also an ethics of dialogue. But it is one which, unlike the metaphysics of unity, does not attempt to put an end to dissent and to "dissensus." Nor, importantly, does it cordon off each vocabulary within its assigned territory -- science here, religion there, art over there in the darkened corner, and so on. Rather the pragmatics of the multiple seeks to enrich each vocabulary through its conflict with the others -- science with religion, art with science, religion with art. (Sanity with madness?) Each vocabulary must remain open to all the others and at the same time respond the provocations it receives from within its own traditions and procedures. A theologian cannot respond to the provocations of neo-Darwinism except theologically; an artist cannot respond to the provocations of religious doctrine except artistically.
In this way a pragmatics of the multiple differs from the demand for mere "tolerance" which asks us to not feel or think about the provocations which are all around us. At the same time it differs from a metaphysics of unity which demands the determination of a final, definitive way of speaking. Nor is it mere relativism, if only because relativism necessarily stands in relation to some absolute against which certain things (vocabularies, concepts, values, etc) are found relative. But the pragmatics of the multiple does not say that the place of the absolute is unoccupied; it says that there is no such place as 'the absolute', or more precisely, that metaphysics of unity is itself a vocabulary, albeit the most curious of them all.