The new language of U.S. politics: polarization

About 700 kilometres separate the Quicken Loans Arena in Cleveland from the Wells Fargo Center in Philadelphia. But, this month at least, they might as well be on different planets.

As Democrat s gather in Philly to officially nominate Hillary Clinton as their party's presidential candidate, they will speak a language that almost no Republican who travelled to Cleveland last week to see Donald Trump crowned as the GOP nominee would understand, much less condone.

Committed partisans in the United States now evolve in such parallel universes, consuming vastly different versions of the news and socializing only among their own, that the likelihood of any ideological, much less physical, cross-pollination of the partisan gene pool is next to nil.

This was not always the case. For most of the 20th century, partisan affiliation and ideological conviction were not one in the same. You could be a Democrat and support unbridled gun rights, deregulation and lower taxes and oppose abortion, affirmative action and removing prayer from schools. Now, anyone like that would would be booed out of the arena in Philly.

There used to be a species called the moderate Republican who supported gun control, government regulation and more progressive taxes, while opposing abortion bans and God in schools. If such a species still exists, it is an endangered one, neither seen nor heard in Cleveland.

The convergence of partisan and ideological affiliations has been the defining feature of U.S. politics of the past quarter century. It's now almost impossible to find a self-declared Republican who is more liberal than her Democratic counterpart, or a Democrat who is more conservative than his GOP peer. The Democratic and Republican parties are no longer arbiters of ideological conflict within their own ranks, but rather agents of ideological polarization.

The largest single group of American voters is not partisan at all. At 39 per cent, the proportion of U.S. voters who described themselves as independents reached an all-time high in the 75-year history of public opinion polling in 2014, according to the Pew Research Center. Only a third of the electorate self-identified as Democrats and 23 per cent as Republicans.

But among the most engaged voters, partisan animus is off the charts. Almost two-thirds of highly engaged Republicans told Pew earlier this year that they were "afraid" of the Democratic Party; while fully 70 per cent of similarly engaged Democrats expressed fear of the GOP. Unfavourable views of the opposing party are closing in on double their 2008 levels.

Like most political developments, separating the chicken from the egg is difficult. Is the rise in partisan polarization the result of an inevitable "sorting" of the electorate along ideological lines, or the product of deliberate political marketing strategies to mobilize and divide the electorate?

Economists Matthew Gentzkow and Jesse Shapiro, along with of Microsoft researcher Matt Taddy, provide a few clues in a new National Bureau of Economic Research paper. They analyzed more than 33,000 speeches delivered by members of the U.S. Congress between 1873 and 2009. Until the early 1990s, they conclude, the "partisanship of language … was roughly constant and fairly small in magnitude." The probability of correctly identifying which party a member of Congress belonged to based only on the words he or she used barely budged over more than a century, at about 55 per cent. By 2009, the probability had risen to 83 per cent.

The inflection point was the mid-term congressional election of 1994 in which Republicans won a majority in the House of Representatives, the party's first in four decades, with their Contract with America. "Innovation in language and persuasion was, by many accounts, at the centre of this victory," the authors explain. In subsequent elections, "Democrats sought to replicate what they perceived to have been a highly successful Republican strategy."

Democratic and Republicans, the authors conclude, "now speak different languages to a far greater degree than ever before." Big changes in the media universe have abetted this trend, with Fox News and MSNBC serving up GOP- or Democrat-speak to their respective partisan audiences.

If anything, Mr. Trump throws a wrench into this analysis by repudiating contemporary Republican language on free trade and U.S. interventionism abroad. This could lead to a GOP schism, though not many gathered in the Quicken Loans Arena seemed to mind their nominee's odd departure from the Republican script. Everything else he said was in their mother tongue.