Dreher correctly bemoans the role relativism in political discussion. An example is that the question of where President Obama was born isn't a matter of fact but opinion, with all opinions being legitimate. Dreher suggests that this kind of relativism has been a part of the rhetoric on the Left in American politics over the past few decades, but that it is appears to be growing on the Right and in the culture at large. Although I share his impression, it would be worthwhile for someone (not me) to undertake an investigation of whether there really is an increase in this kind of thinking.
But for the sake of my brief comments here, I will temporarily assume that the phenomenon we perceive is, indeed, real. It is clear where the relativism on the Left comes from. When explicit Marxism became discredited in academia, post-modernism came to the rescue of every social science charlatan. Its rise in the late 1980s gave ex-Marxists just the cover that they needed. It makes a virtue out of incoherence; It elevates opinion above independently verifiable fact; and it provides you with the ability to call anyone who disagrees with you racist or sexist.
But what I'd like to speculate about here is how the Right managed to adopt the relativism that they correctly scorned for so long. It may just be a consequence of long standing anti-elitist populism. But I'm going to add to the mix of possible sources.
Fundamentalist revival as a source of Relativism
Fundamentalists have always treated relativism as the enemy. Indeed, both Fundamentalists and Relativists need each other as bogeymen. Each say that the alternatives to their own positions is the evil of the other position. In this light it seems more than a bit silly to propose what I'm suggesting. I recognize that I have an uphill struggle in making my case. Also, I still have a lot of homework to do today; so I will have to be brief.
The first time that I heard someone on the Right launch into the rhetoric of Relativism I was both amused and horrified. He spoke of paradigm shifts and that scientific truth only made sense with respect to a specific paradigm, which in turn was a social construct. It was the usual line that I'd heard many times before, but I was surprised by the source. So why was this person on the Right trying to undermine science and facts? Because he was also a Young Earth Creationist. Creationism only works if you deny, destroy, or lie about science. And apparently Creationists of the day had adopted the same attacks on science and scientific reasoning that had been developed by the Left.
Just as post-modernist thinking tried to make a virtue out of incoherence and inconsistency just listen to any Christian try to explain the Trinity or any religious person talk about the mysteries within their belief system. Science has plenty of mysteries, but they are seen as problems to solve and demystify. Religion, on the other hand, treats mystery as supporting evidence.
Just as post-modernism elevated opinion above fact, many religions treat personal revelation as the best (often only) way to establish truth. My personal revelation is as good as yours, and it certainly trumps your facts.
And just as post-modern social science somehow enabled participants to dismiss their opponents as sexists or racists whose arguments and evidence don't need to be considered, fundamentalists know not to debate with the Devil. They explicitly won't consider the arguments of opponents because it might corrupt them.
Religious fundamentalism is a system of thought that (a) attempts to undermine science and scientific thinking, (b) treats its own mysteries as virtues instead of as embarrassments, (c) places unverifiable beliefs above facts, (d) and justifies covering your ears when confronted with opposing views. I'm suggesting that it this system of thought that legitimates relativism exactly among people who should abhor it.
A large grain of salt
What I've said here is highly speculative. It really is more of a plausibility argument than mustering evidence and argument for my suggestion. Furthermore we don't even know if the phenomenon I'm attempting to explain is real. Is relativism growing, and in particular is it growing on the Right? I don't know. But this is a blog, not a research paper.
[Update 2009-12-15: I've corrected many typos and grammatical and punctuation errors. I'm sure many more remain]