Say you're a centrist. If you're like me, one of your most important values is consensus. Another is on procedural checks and playing "by the rules," so to speak. Another is on basic fairness to and deliberation with your opponents--a functional democracy is only possible when all sides are willing to hear each other out and agree to incorporate the best parts of both sides. Under this paradigm, a centrist is a peacemaker--someone who brings both sides to the table while scrupulously avoiding any charges of partisanship him or herself.
My question to everybody today is, under what circumstances is it justified for a moderate to go radical? For example, I consider myself to be pretty radically opposed to the machinations of DeLay and company in Texas, because I think they are a threat to impartial democratic norms. By "radical" I mean I'm not just vaguely suggesting I oppose it--I'm signing petitions, sending letters, and essentially taking the "extreme" position that he should be thrown out of office. On a few other key issues (such as genocide) I also refuse to take the moderate-as-consensus course.
The paradox of moderation is that unless it fights for its values (procedural checks, basic fairness, etc), they will be utterly subsumed in a spate of partisan warfare. Yet the very act of fighting jeopardizes their moderate status. The GOP's treatment of folks like Voinovich during the Bolton ordeal demonstrates this: their actions--even when as restrained as Voinovich's were--to reach across the aisle and not try and seize the maximalist partisan position were seen as a betrayal to the party, not proof of moderation.
My answer is that radical moderation is justified when procedural fairness is on the line. Centrism is only possible when political institutions force extremists to compromise. The tools which create that situation are things like the filibuster, competitive elections, and other entities which give the minority power. When dominant groups try and abolish these checks, moderates have an obligation to use their non-partisan credentials and oppose the effort tooth and nail. I'd also suggest that when matters of basic human dignity are at stake, moderates cannot go for consensus. I actually think this can be subsumed under the procedural fairness standard. Where one group, whether it is by genocide in Africa or by discrimination in America, is being relegated to second-class citizenship (or worse) and is thus effectively removed from the structures of political deliberation, democracy cannot reasonably be said to exist. Moderates thus cannot compromise on laws and policies that offend the equal dignity and respect of citizens of the US and the world.