If you’re a left-winger, then the right-wingers claim that you’re mad, and the centrists say that while you’re not mad, you’re mistaken. Similarly, if you’re a right-winger, then the left-wingers will claim that you’re mad, and the centrists will say that while you’re not mad, you’re mistaken. But if you’re a centrist then no-one says you’re mad, just mistaken. But this is nothing to do with whether or not the centrist position is right. It’s merely due to the fact that they have no opponents who are far enough away from them on the scale to assert that they’re mad.
Interesting thesis, but I'm not sure it's true. First of all, as a centrist myself, I can assure you that I am just as capable as any moonbat of seeing wingnuts for the loonies they are -- that is, of properly employing the concept "wingnut" (and "moonbat" too, of course). And the feeling seems mutual to me as well, from both sides. No advantage there.
W/r/t particular issues, on the other hand (quantifiable ones, say), the thesis is entirely plausible (including its independence from the issue of whether a centrist position is correct or not). But that's not really my subject here (and over there, similar points were made perfectly well by others). Campbell goes on to say that "[t]his reasoning applies not just to political debate, but to any sort of debate on any topic. The centrist positions have an in-built advantage." Now in the philosophical context, here and elsewhere, I have presented my approach to debates like realism vs. antirealism or dogmatism vs. skepticism in just this way, as a mean between extremes -- even, sometimes, with an explicit nod to Aristotle -- and of course in doing so I'm simply continuing in the footsteps of others (Rorty, Putnam, McDowell, etc.; though the all-important details differ greatly). Is there really an "advantage," of the sort Campbell suggests, to doing this?
I should point out that this is not really a test of the thesis, which, again, was intended to apply to specific, e.g. quantifiable, types of case. In fact it presumes the thesis, or at least the intuition that underlies it. That is, I see my favored brand of post-Kantian pragmatism as attractive precisely because it splits the difference between unacceptable extremes. Using the quantifiable image of space, then, we put the point this way: in this picture (which I'm not giving here), the world is independent enough of our minds to escape idealism and relativism, without being so independent as to make a mystery of our cognitive access to it (i.e., in the realist manner). That does sound admirably sane and moderate, as well it should (after all, it's correct).
However, this is hardly decisive. In a way, the "moderation" of this view is an artifact of the conception it rejects, and disappears once the alternative comes into view in its own right. In other words, the situation can be seen just as well as a choice not among three views (two extremes and a center), but between two (the traditional and the pragmatist). In this sense, the two "extremes" are much closer to each other than either is to the "center." In fact, again, they're the essentially the same position, only with opposed orientations. Rather than moving toward the "center," then, in this sense we simply exchange a defective picture (one which, as Wittgenstein puts it, had been "holding us captive") for another. The defect is just what made it seem that there was a forced choice between two opposed positions, instead of a single dualistic picture we should reject for that very reason.
But now we seem to lose the "advantage" of the putative "moderation." What we had been seeing as extremes now join forces to gang up on us, defending their shared conception against the "counterintuitive" newcomer. Yet at the same time, each also sees the pragmatist as in league with his opponent (that is, as trading a winning position for a losing one). Just as in (some of) the political case(s), one person's virtuous moderation is another's concession to vice. By itself, it seems, the structure of the dispute can't determine which side is right.
Let's look again at (a simplified version of) our example, realism vs. antirealism (it works the same way, mutatis mutandis, for skepticism vs. dogmatism). The realist sees the world as independent of the mind, as "objective"; the idealist disagrees. Which is right? Above, we saw the "moderate" answer ("independent enough, without being ideally (i.e., "absolutely") independent"). But realists and idealists don't see this as sane moderation, but instead as wishy-washy dissembling. To dispel this impression, the pragmatist must switch from the three-position image -- the only one which can even appear "moderate" -- to the two-position image. The realist and idealist seemed opposed, and it looked like we had to choose between them where they differ. The "moderate" view was a way of seeing them as both (almost) right (that's the "carrot"). But (here's the "stick") we can just as well see them as both wrong, where they agree. Both are committed, that is, to the same dualistic picture of objectivity. Here of course is where the idealist will object (the realist will cop to it and stick to his guns, accusing the pragmatist of idealism for rejecting it). After all (he'll say), it is just because the realist picture is indeed dualistic that we must be idealists; that's the point of idealism. Where's the dualism, if the world does not transcend our ideas?
The answer is this. The realist puts everything into two boxes: the objective (the world), and the subjective (ideas). Seeing that such a division is senseless, the idealist puts everything into the second box. But we still have a two-box picture, even if one of the boxes is empty. The conceptual dualism -- to my mind the important one -- is still in place. To overcome it we must reconfigure the notion of objectivity. When we do so we will still find it informative to distinguish, in particular cases and senses, between ideas in the mind and the world which (in an equally reconfigured sense) they represent. (Here's where Rorty, for example, is being obtuse, when, without qualification or explanation, he says simply "I have no use for the idea of objective truth." That's just what makes pragmatism look like the rankest idealism. Of course that's not really an excuse for the uncharitable interpretations of some critics; but it's careless all the same.) We simply give up the traditional (i.e., seen as obligatory, even constitutive of philosophy itself, on the traditional picture) metaphysical/ontological project of dividing things up into one or the other. In this sense the realist and idealist are both unsatisfied with pragmatism (that is: to remain unsatisfied just is to be realist or idealist): there is no "objective world" (realist rolls his eyes) -- but that doesn't mean everything is "within the mind" (idealist frowns).
Once again I have failed to give the content of the "reconfiguration," apparently leaving open (or begging) the question of who is correct. But consider this: what if describing the necessity or process of reconfiguration often and imaginatively and persuasively enough makes it unnecessary actually to fill in its content (that is, we get the point -- give up the defective picture and learn to see properly -- anyway)? Or what if the former just is the latter? Or (hold onto your hats) what if these two possibilities are the same one??