The Washington Post editorial page has an interesting scoop on Grover Norquist's tax pledge:

WITH A HANDFUL of exceptions, every Republican member of Congress has signed a pledge against increasing taxes. Would allowing the Bush tax cuts to expire as scheduled in 2012 violate this vow? We posed this question to Grover Norquist, its author and enforcer,and his answer was both surprising and encouraging: No.
In other words, according to Mr. Norquist’s interpretation of the Americans for Tax Reform pledge, lawmakers have the technical leeway to bring in as much as $4 trillion in new tax revenue — the cost of extending President George W. Bush’s tax cuts for another decade — without being accused of breaking their promise. “Not continuing a tax cut is not technically a tax increase,” Mr. Norquist told us. So it doesn’t violate the pledge? “We wouldn’t hold it that way,” he said.

It's pretty strange, isn't it? Apparently Norquist interprets his pledge in some ultra-literal way that precludes it, in the case, from fulfilling its primary purpose. On the other hand, a plan to pass a one-dollar tax hike while cutting federal spending in half would violate the pledge.

So if you can allow the Bush tax cuts to expire, can't you set future tax rates that would provide for lower revenue levels than under a scenario where they expire? And why hasn't anybody thought of this loophole before?