As a rule, it is distasteful and counterproductive to equate one’s political opponents with murderers of the innocent. Claiming that someone has “held the budget hostage” is a metaphor. Calling someone a “terrorist” is an excuse for a fistfight. But Biden’s obvious flaw is foolishness, not viciousness. The first we would forgive a friend; the second is harder to overlook. When Biden later said that Gabrielle Giffords is “now a member of the cracked head club like me,” it was tasteless. But who could accuse Biden of being intentionally cruel toward Giffords? Biden lacks the normal filter of appropriateness. But an unfiltered Biden is not, as far as I can see, an angry or heartless man.

Tossing around a word like “terrorist” slips a little more poison into our political discourse. But so does the taking of exaggerated offense – the political equivalent of flailing in dramatic reaction to a basketball foul. In politics, as in life, the motive of an insult matters.