by Scott F. Aikin and Robert B. Talisse
In some cases of disagreement, we may know more about the issue than the other person. And in some cases, the other person may know more. Call these asymmetric disagreements, and a regular thought is that in these cases, the less knowledgeable person ought to defer to the more. However, it's possible for there to be symmetric disagreements, where both sides are roughly as knowledgeable of and capable with the evidence on the issue. The individuals in these instances, then, are peers, at least epistemically.
In these symmetric cases, how should these peers view their own and their disagreeing interlocutors' commitments? By hypothesis, the two opposing views are based on the same evidence, so it's not that one can view one side as better informed or less knowledgeable than the other. And it seems dogmatic, or at least unfounded, to say that one just knows (without more evidence) that one's view is better off than one's opposition.
A background question to this matter is whether it's possible for a set of evidence to justify more than one view about an issue. One take on the question is that, given a set of evidence, there is only one attitude a person may take about it – one may accept a proposition as justified, one may reject it and hold its denial as justified by the evidence, or one may be justified only in suspending judgment on the matter. Of these three options, only one of them would be rationally responsible. Call this view the Uniqueness Thesis – that there is only one attitude that any set of evidence justifies.
In contrast to the Uniqueness Thesis, there is the more ecumenical view that there are many attitudes (or at least more than one) that can be justified by an evidence set. Call this view the Pluralist Thesis – the evidence underdetermines what is uniquely justified, as there may be inconsistent views justified by it.
Pluralists and uniqueness theorists do not only have views about first-order disagreements (about dinner, professional issues and highway ramps), but they also have views about how the evidence justifies the sides in the (presumably symmetric) uniqueness-pluralism debate. Pluralism and Uniqueness are second-order views, too, and they apply to themselves and the disagreements in which they are implicated. (An earlier post on this point here, and we have a short video explaining it at Philosophy15 here.)
Uniqueness theorists can handle this self-reference without much difficulty. They will hold that there's one right answer to their disagreement with pluralists, and it is their own. But pluralists have a problem, because it seems they should hold that uniqueness theorists are justified in holding their views, too. And so the evidence, then, justifies not only the uniqueness theorists, but the pluralists too, in rejecting pluralism. Yet pluralists also hold that the evidence justifies pluralism, since this is what they must think of their own view. The result, it seems, is a contradiction, and one that derives directly from intellectual pluralism itself. In fact, it seems that the intellectual pluralist must think that the non-pluralist is not even wrong, but being perfectly rational in being a non-(or even anti-)pluralist.
This, we think, is not strictly a self-refutation argument against the pluralist. This is because the pluralists acknowledge that part of their view is that there is a contradiction at the heart of value. They hold that Reason, as it were, must come to terms with this deep tension, and our argument may be just one more reminder of that deep tension. But views have costs, and we think that the costs of pluralism's intellectual permissiveness are too high. We will mention three significant costs.
First, it's not clear what the pluralists should do once they have conceded that the evidence will never determine what's justified, as opposed to what's not justified. Insofar as arguments are about marshalling one's evidence and weighing it out, then argument (on the first and second order) will be beside the point. What does evidence do? What rational means does one have? And when one chooses one's means, must one have reasons for and against it, too?
Second, once we have reached this point where reason and justification yields contradictions, it really isn't clear what rational and justified meant in the first place. If justification is supposed to be what plays a sorting role for beliefs or commitments, and rationality has distinctive qualities, then pluralism has degraded those functions significantly. (We have written on a version of this problem earlier, here.)
Third, and finally, it doesn't seem that pluralism can endorse any positive program on the first or second order, since it will also be in principle committed to endorsing the program's contrary. It must be, by its own lights, useless as an intellectual attitude. This, of course, doesn't make pluralism false, but it certainly is a practical reason to hope that it is.