The American political system isn’t working for average Americans anymore. Don’t blame the Tea Party, new political science research suggests. Blame inequality.

By Sam Pizzigati

In a sensible republic, democratically elected leaders come together in a respectful give-and-take to debate the problems that confront the people they represent. Eventually, these leaders, all debated out, come to agree on a set of solutions. They enact these solutions. The society progresses. End of story.

In real life, something approximating this political fairy tale can take place — but only in societies where most everybody first agrees on the problems that deserve debating. And that agreeing, in turn, usually only comes when the great majority of a society’s people lead similar sorts of lives.

All this may explain, suggest some of America’s top political scientists, why 21st century politics in the United States has polarized into hostage-taking gridlock.

People in the United States today don’t live anything close to similar sorts of lives. They live amid a level of inequality unseen since the early 1900s. And those early 1900s, note Princeton political analyst Howard Rosenthal and the University of Georgia’s Keith Poole, also saw intense political polarization.

But not as much as we have now. The level of polarization in the U.S. House of Representatives, Rosenthal and Poole observe in their latest research, has now topped the previous high, set in 1905.

In this latest work, and in a 2006 book on “the dance of ideology and unequal riches” co-authored with Nolan McCarthy, Rosenthal and Poole have developed a variety of indexes that measure political polarization, in Congress and the nation at large. Inequality and polarization, these indexes show, go hand in glove.

In the middle of the 20th century, years that saw the United States grow steadily more equal, American politics became less polarized. Since the mid 1970s, polarization has increased. The turning point, the scholars note, “occurs almost exactly the same time that income inequality begins to grow after a long decline.”

Political scientists in the United States, over recent years, have been giving this increasing inequality increasing attention. In 2004, the American Political Science Association’s Task Force on Inequality and American Democracy published a series of research papers that rigorously explored how the nation’s growing concentration of income and wealth is playing out politically.

“The recent growth in economic inequality,” task force researchers concluded. “appears to be increasing the power of individuals and groups who have a stake in doing little or nothing about substantially counteracting disparities based on income and wealth.”

In other words, gridlock. Wealth that concentrates, the task force research detailed, can flex more power. Wealth enables greater access to “tools” for manipulating public opinion, for instance, and the result can be “a subtle, indirect, but pervasive kind of inequality in political influence.”

Wealth’s concentration also helps explain today’s utter indifference of ultra conservative lawmakers — and their well-heeled funders — to the consequences of cavalierly slashing funding for basic public services.

The United States currently sports a significant population of wealthy people who don’t use and don’t feel they need public services. These wealthy don’t send their kids to public schools. They relax in private country clubs, not public parks. They never ride public transportation or borrow books from public libraries.

Over time, these wealthy come to bitterly resent having to pay for services they never use. The wealthy back in America’s more equal 1950s and 1960s harbored these resentments, too. But those wealthy didn’t have the critical mass — or personal fortunes grand enough — to translate resentment into domineering political power. Today’s wealthy do.

The Great Recession, new IRS statistics released last week show, has only reinforced the concentration of income that fuels this domineering power.

In 2009, notes an early analysis of the new IRS data from Center for American Progress analyst Seth Hanlon, taxpayers who reported at least $1 million in income made up one in 500 of the nation’s tax filers. Yet these same wealthy Americans took home almost $1 of every $10 in national income.

More specifics from the new IRS stats will be emerging in coming weeks. The new specifics will likely all deliver the same sobering message. Buckle up, America. Our polarized national political ride figures to get even rougher.

Sam Pizzigati edits Too Much, the online weekly on excess and inequality published by the Washington, D.C.-based Institute for Policy Studies. Read the current issue or sign up at Inequality.Org to receive Too Much in your email inbox.