See, Negative Campaigning Works.

I've written two books on negative campaigning; one on campaign tactics and one on the most vicious campaigns in history. A constant theme of my research and that of others' is that when used well, negative campaigning can be very effective. We're seeing evidence of that right now in Iowa.

Negative campaigning, of course, has a bad reputation and voters routinely say they don't like it and don't want to see it. But candidates keep using it for one simple reason: it works. If it's used...