Extremists

And then there are the conservatives (liberals) for whom a refusal to demonize liberals (conservatives) makes you one.

Here is the first stanza of "The Second Coming" by William Butler Yeats (1865-1939):

    Turning and turning in the widening gyre
    The falcon cannot hear the falconer;
    Things fall apart; the centre cannot hold;
    Mere anarchy is loosed upon the world,
    The blood-dimmed tide is loosed, and everywhere
    The ceremony of innocence is drowned;
    The best lack all conviction, while the worst
    Are full of passionate intensity.