I am about to attend the second day of a very interesting conference on pluralism. Since everyone at this conference is convinced of some sort of pluralism I thought I ought, as a good pluralist, argue against pluralism. The basis of my sceptical argument shall be that pluralism is correct, so I am confident it shall win assent among my comrades and colleagues.
What makes for a good scientific explanation of a given phenomenon? Is it, perhaps, a valid argument, the premises of which are true and contain at least one law-like statement (without which the argument would not be valid), and the conclusion of which is a description of the phenomenon? Is it, instead, a description or production of a mechanism which, when operative, suffices to produce the phenomenon? Is it, against both those options, a unifying and parsimonious theory, which in-some-sense entails or otherwise predicts the phenomenon in question along with many others of interest? Or is it all of the previous, and perhaps other things besides?
Pluralists favour the last of these options. We need not pick among these options; good scientific explanation can be many things, they say. And, this is a move which crops up in a lot of places in sciencey parts of philosophy (and perhaps other places besides, which I don't comment on out of ignorance). What ontology best fits our physical theories? What sort of methods are most reliable for scientific inquiry? What makes an argument logically valid? These are all questions which have received a similar pluralist treatment to the question of the nature of good scientific explanation -- philosophers (and scientists and mathematicians) offered various accounts, and eventually some wit came along and said that perhaps each can have its place in its own domain, or that each can be counted equally well true (on some understanding of `equally well true'), or that each would be a best fit depending on one's purpose, and so on and so on. In short, after protracted debate between various accounts, the pluralist comes along and offers an account which says that all or most of the main contenders can be seen as in some sense correct, only chiding them for being over-ambitious in their claims to exclusive possession of the truth.
Ok so now for my sceptical argument. I begin with a word on why I think pluralism is nearly almost correct, or at least the account most likely to be true from those we've yet developed. There are two main reasons for this. First, usually pluralists seem to me to be asserting a disjunction. Where previously there were theories A, B, or C on the table, competing in their attempts to characterise X, the pluralist comes along and finds some way to see things such that the truth about X is that it is A or B or C. At the least, then, the pluralist cannot be doing worse than their disjuncts when it comes to likelihood of being correct! Now, there are many versions of pluralism, and it is always contentious how to characterise pluralism about a domain, and I am sure many pluralists should not like this characterisation. But this is how it often seems to play out in conversations I am party to. Minimally, I think that many statements of pluralist positions about a topic matter leave it ambiguous as to whether their account would be either vacuously true or refuted if it turns out that all the actual cases of X we ever need to care about can be chracterised as of type A. My instinct is that the pluralist in that scenario has it open to them to say that, perhaps so, but none the less Xs of type B or C would have been perfectly good Xs; but others may think that in this case the pluralist really is refuted. (In fact, I think there is more to say here, but it turns on the metaphilosophical point discussed below -- so I'll return to it later!)
My second reason for thinking pluralism is true is just a matter of optimism about people, or trust or faith in their ability to inquire, or something of the sort. Usually the dialectic in the development of pluralist accounts of various objects of interest goes as follows. Some non-pluralist begins by offering a theory of X, and showing how their theory of X does ever so well at accounting for the appearance of X in cases 1, 2, and 3. Then, alas, some other non-pluralist comes along and says: well not so fast, for in cases 3 and 4 the first account doesn't do so well, whereas this rival account would get them perfectly -- and perhaps cases 1, 2, and 3 can be brought under the purview of the rival account too, come to think of it... And so it goes, with long-running unresolved-dispute and a proliferation of cases. Until eventually a pluralist descends into the saṃsāra and brings peace to these troubled folk by ending their craving for a single unified and exclusive account of X. (At least such is the plan.) Well, in cases like this, it just seems to me a pretty natural reading of what is going on is that the various non-pluralist disputants, smart and earnest folk that they are, have each got at an aspect of the truth about X, or grasped-how-X-appears-in-some-cases; and in so far as the pluralist is just acknowledging that then I am on the pluralists' side. Think of that trope of the blindfolded folk grasping at the elephant, and all that. Neither of these arguments is conclusive, of course; that's why I am publishing them in a blog post without referees to get in my way! But they sway me towards pluralism in nearly all cases.
So if I think this why don't I like pluralism? Here I think it turns on what I take the purpose of philosophical inquiry to be. To state the matter far too briefly, I don't think the world needs us philosophers (the sentence would be true if it stopped here) to agree upon the truth of the matter regarding our various topics of interest. A lot of the benefit philosophers do comes from the way we refine various conceptual tools, or make available new options, or keep alive old options that folk in other fields think ought be rejected, or produce beautiful and inspiring aesthetic objects. (This list could be continued -- I am a pluralist about the benefits of philosophy, of course, I only downplay ``produce true theories of philosophical domains''.) These do not require us to come to consensus about the truth of the matter. At most, the truth about our topic matters can be instrumentally useful to some of these tasks, but on the whole I think this rarely occurs. So the fact that pluralism is most likely to be correct does not seem to me to be a very good reason for philosophers to adopt it. Instead, pluralism often seems to me to make it less likely that we as a community shall attain various of the goods listed.
For, pluralism gets us to accept a truth which can too easily accommodate rival claims. If somebody offers some new theory (even if they insist that they are not pluralists, that this the One Truth about the domain) then a canny pluralist can, in so far as the new theory is plausible, always just extend their disjunction by one more disjunct. Whatever the equivalent to Popperian falsifiability for abstract philosophical claims is -- pluralism lacks that. And I think this constant fear of being wrong, and proven to be so by one's accursed rivals, is a useful feature of philosophical life. Take, for instance, this defence of pluralism about social scientific methodology. Since I speak to the authors, I happen to know that at least one of them was (in part) motivated by a desire to put to rest arguments between those who favour quantitative and qualitative methods in the social sciences. Now, I share this author's irritation with such arguments. But is that a good reason to defend pluralism? For, such arguments seem to me to have been productive in generating interesting novelties, as each side has had to refine its methods in response to the critiques and teasing of others. The development of process tracing in political science seems largely to have been spurred by felt rivalry (and indeed somewhat of an inferiority complex in comparison) with quantitative methods, and I know of an attempt to develop formal tools for reasoning about intersectionality theory that was in part goaded by claims (coming from qualitative theorists) that it was impossible. The pluralist move in these cases would have, if widely accepted, taken away a significant spur to such inquiry, and does not have anything it obviously offers in the place. Fear, jealousy, pride, overweening ambition -- these are the stuff of philosophical progress. By appealing to the better angels of our nature pluralists will damn us all.
Having said all this, I will end by taking it back. Love and kindness and cooperation and a generally chill attitude have their place in philosophical inquiry too. But one shouldn't let mere truth get in the way of a tweet-sized pull-quote. And some of it was just me trying to extend my love of Feyerabend's counter-induction to the case of philosophy. But the fact that something appeals to my inner teenage rebel hardly seems like a good reason to accept it. What's more, in fact, I think what I say here is even more internally incoherent than it appears on the surface. For, I think this relative indifference to the truth in philosophy is the reason why pluralism seems to me to be asserting a disjunction: I do not much care if accounts A and B of explanation do not really count as good explanations but only C does, if it turns out that along the way to developing accounts A and B various innovations were made that can be useful in other contexts. For my intents and purposes, if you convince me that A and B and C can all be useful or illuminating regarding X in their own way, then it seems to me that one has said that we can accept A or B or C as achieving exactly what philosophy is meant to achieve. But, then, am I not in this relative indifference to the truth undermining any reason for proponents of these respective options to engage in jealous rivalries? Well, no; but only because nobody cares what I say about anything.