Proving that an argument is invalid (ideally by showing that it ends in a logical contradiction) is one of the most effective ways to destroy an opponent's case.

In order to understand the substance of the prepared responses we are likely to hear tonight, you need to keep in mind the true audience the candidates are appealing to, which includes their own base and undecided voters (especially in swing states), as well as the media.

Americans who looked to Barack Obama's speech for inspiration likely got it, if at all, from the same place he says he gets his -- from his litany of remarkable Americans who have continued to soldier on and succeed against long odds.

Today, we know a lot more about mental illness than we did forty years ago. But given the grueling and brutal demands of modern campaigning, we would be extremely unlikely to embrace a presidential candidate who acknowledged taking drugs for a psychiatric condition.

WASHINGTON -- It's been a subtle alteration but an alteration nonetheless. In his past two campaign speeches, President Barack Obama has adopted a con...