Ryujin
Legend
"Radical" and "extreme" are not well-defined terms.
For example, right now, if one of the candidates tried to open a conversation on gun control, you can be pretty sure the other side would call that candidate 'extreme left'. Heck, they have called Obama a 'socialist' (which, yes, shows that the speaker knows squat-all about socialism, but the point stands).
As with Justice Potter Stewart regarding pornography I don't know that I can define those terms adequately, but I know it when I see it.