The anger seething across the American political landscape — over racial changes in the population, soaring public debt and the terrible economy, the bailouts of bankers and other elites, and an array of initiatives by the relatively liberal Obama Administration that are seen as "socialist" or even "fascist" — goes beyond the radical right. The "tea parties" and similar groups that have sprung up in recent months cannot fairly be considered extremist groups, but they are shot through with rich veins of radical ideas, conspiracy theories and racism. Already there are signs of similar violence emanating from the radical right....