Last night Barack Obama said, "If John McCain wants to have a debate about who has the temperament, and judgment, to serve as the next Commander-in-Chief, that's a debate I'm ready to have."

This morning John McCain confirmed the problem to which Obama alluded. His choice of Alaska Governor Sarah Palin as his running mate is precisely the impulsive, risky sort of gamble that is a McCain trademark. He saw himself as losing, especially after the Democratic National Convention went so well. So he decided to roll the dice by choosing a woman--any woman, no matter how inexperienced and unknown.

The issue at this point is not about Gov. Palin, about whom we don't know enough to be too critical. The issue is about what choosing her says about John McCain.

Don't criticize the choice; criticize the chooser. He shoots first and asks questions later.

The VP choice is of a piece with McCain's quick, decisive, simple answers to Rick Warren's questions at the recent religious forum.

Even more, it is of a piece with Sen. McCain's readiness to go to war--with Iraq, with Iran, with Russia--don't talk, attack!

When it comes to picking the person who will have his finger on the nuclear button, we don't need a gambling man who loves to play craps--not when we are the stakes he is gambling.

No dice to a candidate who is so ready to roll the dice.

{Historian Robert S. McElvaine is Elizabeth Chisholm Professor of Arts & Letters at Millsaps College. His latest book is Grand Theft Jesus: The Hijacking of Religion in America .