Gentlemen, I nominate this man. If you can top this, I dare you to find a columnist who writes crazier articles. I dare you.
http://www.creators.com/opinion/ben-shapiro/the-case-for-israeli-settlements.html
http://www.creators.com/opinion/ben-shapiro/an-open-letter-to-american-jews.html
http://www.creators.com/opinion/ben-shapiro/enough-of-radical-islam.html
And just try to look up his mini-biography at the bottom of the page, and his background from elsewhere, and you may come to some interesting conclusions about what helped make this man a columnist.
One thing I've learned over the years is never to speak too soon and that if there is something someone can believe, someone is out there believing it (no matter how inane or bizarre).
Because of that, I can't answer the question posed by this thread. Someone will just disprove my argument, I'm sure.
Paul Krugman - hands down.
+1
There is always David Brooks, especially for this article the other day http://www.nytimes.com/2010/06/15/opinion/15brooks.html?ref=davidbrooks
"Man thinks not only for the sake of thinking, but also in order to act."-Ludwig von Mises
Brooks is more of a charlatan, not so much insane. I say Krugman because the guy keeps repeating the same stuff that is clearly wrong many times over, plus he shows paranoid tendencies.