Why relativism leads to totalitarianism

I’d like to spin off from our reflection a comment Lars Walker made, as we blogged about yesterday in the post The Bible and Liberty:

As Paul Johnson notes in Modern Times, moral relativism always leads to Totalitarianism. Because in a morally relative age, power alone can settle any question.

Now that we are in postmodern times, as any survivor of mainstream academia can testify, the postmodernist thinkers themselves are pretty much admitting this, claiming that since there are no absolutes, everything does, in fact, boil down to the exercise of power.  All philosophies, ideologies, values, moralities, and truth-claims, so they say, are nothing but masks for power.

So far postmodernist intellectuals seem to decry this, unmasking the power assertions of the “privileged” as an exercise in liberation.  But it isn’t clear how they can escape their own assumptions and evade their own impositions of power–whether when the “oppressed” become the new rulers or in their own political activism or in the way they themselves treat people who disagree with them.