From my balcony on Manhattan's Westside, I can see the spot on the Palisades above Weehawken, N.J., where Aaron Burr shot Alexander Hamilton in July, 1804. Hamilton, a Federalist, had called his Democratic-Republican adversary "a dangerous man ... not to be trusted with the reins of Government." Burr responded by challenging America's first Secretary of the Treasury to a duel. Hamilton, mortally wounded, died the next day.

Nowadays, politicians no longer settle their scores on the dueling grounds. They reserve their best shots for debates and Sunday morning talk shows. And they don't limit themselves to expressions of patrician contempt. Hamilton's rebuke of Burr would scarcely register on today's Richter scale of political insult. It would not even make it onto Fox News.

As the Republican primary season drones on, we have seen a level of rancor and character assassination rare in the team-playing GOP. Never before have so many violated Ronald Reagan's 11th Commandment ... thou shalt not speak ill of another Republican.

Should we begrudge the candidates their harmless mudslinging? Linguist Kathryn Ruud, a contributor to the book, "At War with Words," argues that much of what we hear today is no longer harmless, but destructive of the minimal level of civility which a democracy requires to function. We should learn some lessons from our founding fathers. While they were no strangers to political controversy, Ruud says, America's founders exercised restraint in public because "they understood the difference between the ethical and unethical use of strong language." Nowadays this crucial distinction is being lost.

Politicians aren't the only ones to blame. They've taken their cues from the tribal blogosphere and talk radio, where the battle for ratings has fueled a race to the bottom of the verbal pack. In such an environment, politicians ramp up their rhetoric to appeal to their own increasingly radicalized base. Moderate views are marginalized and America gets divided into mutually non-communicating camps, where it is OK to express hatred and contempt for ones political rivals.

History demonstrates that hate speech leads to hateful acts. The abuse of language on talk radio and elsewhere was surely a factor in the Oklahoma City bombing in 1995 of the the Alfred P. Murrah Federal Building, which claimed 168 lives, and in the Tucson shootings of Representative Gabrielle Giffords and 18 others last year.

As a linguist, Kathryn Ruud traveled to Munich where she studied Hitler's speeches in the original German. She was shaken by the chilling resemblance of his language to some of what she had been hearing on American talk radio.

Ruud is quick to add that America's homegrown demagogues are not in the same league as the founders of National Socialism. Yet they employ many of the same verbal tricks to create revulsion in their listeners for "the other."

Hitler, a master of dehumanization, called Jews "parasites," "bacteria," and "vermin," thereby preparing the German mind for the holocaust. Limbaugh, for his part, calls liberals "maggot-infected" "parasites" and Glenn Beck refers to progressivism as "a disease," "an infection," "a cancer eating our constitution."

Another of the German Fuhrer's techniques was what Ruud calls "lexical fusion," lumping together hated groups, however dissimilar they may be, into a single monolithic enemy. Hitler spoke of "Jewish Marxists," and "fascist capitalists." Rush rails against "the liberal media," and "liberal, socialist, communists." This vague and faceless group is made the scapegoat for all that is evil in society.

A key to brainwashing is keep it simple. Nazi information chief Joseph Goebbels wrote: "Propaganda ... must always be essentially simple and repetitious. Only he will achieve basic results in influencing public opinion who is able to reduce problems to the simplest terms and who has the courage to keep forever repeating them in this simplified form despite the objections of the intellectuals."

To be sure, the dumbing down of political discourse owes more to focus groups and opinion polls than the teachings of Joseph Goebbels. Political campaigns are increasingly engineered by marketing specialists who rehearse politicians in talking points, and craft negative ads to demonize their rivals. Rather than using their election year soapbox to reason and persuade, candidates now routinely play to the fears and the prejudices of the crowd. They employ fighting words designed to tap into people's hidden wells of rage.

For all who care about the future of the American democracy, these are worrying trends.

Schiffman is author of two biographies. His work has appeared on NPR; in The New York Times, Salon, The Washington Post, The Christian Science Monitor and the Huffington Post, where he is a regular blogger.