Even when they do manage to deal with issues, positive policy proposals are presented in a facile manner, frequently with untruths and a complete unwillingness to face up to the likelihood of success versus failure. Donald Trump's critics have loudly proclaimed that most of his ever-changing policy proclamations are impossible to carry out.

Trump and his supporters have said the same about some of his competitors' plans, and will undoubtedly try to use the same arguments against Clinton. The only way for voters to actually judge these arguments is negative campaigns. Positive ads will not expose the elisions. Only negative ones have any hope of blasting holes and exposing the policy weaknesses of a candidate's pie-in-the-sky plans.

But that is not the biggest benefit of negative ads. They are simply more truthful and fact-based than negative ones. Vanderbilt University Professor John Geer, the author of In "Defense of Negativity: Attack Ads in Presidential Campaigns," has noted that negative ads may be unpleasant but they end up presenting vastly more factual information—60 percent more on average—than the shiny happy positive variety.

What negative ads do is present a strong policy contrast for voters, giving them a chance to draw a real distinction between the two candidates. Negative ads distort information—context is always left out and they take the absolute worst possible interpretation of any action by an opponent. But they are usually very issue-based and much more precise and detailed than the positive and glowing ads in favor of a candidate.