EVANSTON, IL -- As the world media was stunned yet again by gruesome video of insurgents executing an American hostage just on the heels of the release of ghoulish images of Americans tormenting Iraqi prisoners, many experts are saying that the two events somehow justify or overshadow each other.
    "In fact, one evil can sort of 'cancel' another one out," said Leonard Puckett, professor of retribution studies at Northwestern University. "It can even work retroactively if the situation requires it."