There can no longer be any doubt: Sarah Palin is absolutely, positively not qualified to be commander in chief, and she doesn't belong on the Republican ticket. I can't imagine her being ready for a 3 a.m. call on a national security emergency; I can't imagine her fielding one on an economic emergency, either – the possibility Paul Krugman convincingly framed Monday morning.

Her stunning ignorance about Israel, Iran and the Bush Doctrine in the Charlie Gibson interview almost three weeks ago was frightening, but the dim way she answered virtually every question Katie Couric asked last week was even more chilling.

Ever since, she has continued to gaffe her way through the campaign: On Saturday she said she'd go after Osama bin Laden in Pakistan – even though that's against the McCain position, and McCain had to contradict her publicly. Newsweek's Fareed Zakaria says it best: All too often, when Palin opens her mouth, what comes out is "gibberish."