Politicians of all parties have been bending the truth since the beginning of the republic. The two previous presidential administrations are perhaps best known for lies or untruths -- see Lewinsky, Monica, and weapons of mass destruction. And even in this, another presidential election year, rare is the day when a candidate does not utter or repeat a claim that will be debunked by an independent truth squad. Why do they do it? Those who study politics and communications say the consequences appear to be minimal.