Agreed. Just calling him barking mad doesn't effectively knock down his points. What seems prima facie nuts to those of us who eat and breath this stuff every day, gets credibility by default because

1)he is an academic who publishes a book and is on Fox news...and

2)no one on the left bothers to note that the very premise for the 'clash of cultures' argument is factual nonsense--not just a poor opinion (which many including K. Pollit, E. Alterman, dKos readers, etc...have done in abundance)--but factually inaccurate, as in, opposed to statistically verifiable reality --and, as a consequence, all the nasty stuff that's derived from it can get a kind of intellectual 'free pass' as well--at least for those 30% who are already nodding their heads...

So I think D'Souzas little rant offers an excellent opportunity to do a top to bottom critique of the right's world view. Starting from a factually insane premise and working our way outward. FYI, where I intend to wind up is Axelrod's gaming experiments and a strong argument for the evolution of cooperation as a moral and cultural end point.