When there are no boundaries, how do you define the center?

Steve Bates collects the blogs that have defined centrism.

Jane Hamsher of Firedoglake:

"In fact "centrism" is not antithetical to populism, and both are, in pure abstract terms, measurements. If an axis of opinion can be established with two discernable poles, then your opinion is "centrist" if there are equal numbers of those who stand to one side of you as another. If more people feel their interests lie on one side of the spectrum rather than another, it is generally assumed to have a populist base of support (as I believe Kevin is using the term here, contra elite "blue ribbon commissions"). And as Atrios notes, imposing a right/left dichotomy on most issues thus abstracted is both awkward and frequently misleading.I don't think I've ever rejected a position simply because it was "centrist," it would be like having a problem with long division. Rather, I get a bit irked with the smug certainty of pundits and politicians who think the wisdom of their position should be respected because it is "centrist" when they have not in fact established that such a measurement is applicable, or why (if it is) this should lead to some knee-jerk assumption of validity."

[snip]
"Aesthetics are not metrics. John McCain's ability to laugh casually and tell a good joke on the Daily Show does not mean he is not morphing into a cynical right-wing wacko before our eyes. And those who want to invoke the "centrism" of their ideas are going to have to try a little harder to establish both that they are, and why we should care."

Ezra Klein: (my bold)
"Guys like Sebastian Mallaby, Robert Samuelson, and David Broder make a play at pushing marginally useful, technocratic ideas as a way of dismissing progressive ones. In these instances, the idea is subordinate to its perceived position on the ideological spectrum. When "centrist" ideas become a navigational device rather than a policy proposal, that's wankery. And it should be opposed. When a good idea emanates out of a centrist, or even conservative, source, that's a good idea."