(By Z, I think you mean Alain Besencon).
I'm going to respectfully disagree, Michael. I didn't hear him say anything about discussing things --- he said "refuse [to recognize] --- without discussion" any "elements of truth" that the other side proposes. To me this is not merely refusing to accept the assumptions underlying the debate --- to discuss matters on another's "terrain". His claim was much narrower, that once you grant that there is an "element of truth", "you're lost". This sounds very wrong to me, very frighteningly wrong. One thing about the right is its ability to construe all opponents as Pure Evil. I don't want to see the good guys taking that tack, whether it's during face-to-face discussion or publicly-held forums.
I mean, take the "description of reality" that, say, Thomas Jefferson put forward. He had some awful things to say about blacks; but he was opposed to the death penalty, and according to his biographer Dumas Malone also found that public labor produced in inmates an "abandonment of self-respect which plunged them into the most desperate and hardened depravity" (Malone). Surely, we are opposed to Jefferson's views on Blacks, and plenty of other things, but does that mean we must "refuse --- without discussion" everything Jefferson had to say? Or can we say that Jefferson retained "multiple ideologies" and therefore we can treat them in a compartmentalized fashion? I just don't see the point.
One of things I admire about Chomsky is that he can be very even-handed in describing the most depraved of persons. He simply treats them as human beings with the familiar limitations, and demolishes their cases bit by stinking bit.
The strength of our case must lie in the truth. Refusing to recognize that very often the truth can coincide with the most depraved of lies is to, I think, yield to a temptation to see our case as thereby weakened --- that somehow since the truth does not exist solely on our side, our side must have somehow lost this conserved quantity to the bad guys, which it has not.
In fact, let me go further: *unless* we recognize the elements of truth in "ideological regimes", we cannot adequately fight them. We must recognize that we are battling with human beings --- who can be very adept at mixing truth with falsehood --- not comic-book incarnations of pure evil.