He demands that they work hard in school, declaring that "at the end of the day, we can have the most dedicated teachers, the most supportive parents and the best schools in the world - and none of it will matter unless all of you fulfill your responsibilities. Unless you show up to those schools; pay attention to those teachers; listen to your parents, grandparents and other adults and put in the hard work it takes to succeed."

The president has no patience for losers who blame others for their own failings. He tells students that "the circumstances of your life - what you look like, where you come from, how much money you have, what you've got going on at home - that's no excuse for neglecting your homework or having a bad attitude. That's no excuse for talking back to your teacher, or cutting class, or dropping out of school. That's no excuse for not trying."

Oblivious to the realities faced by many disadvantaged young people, the president drones on about the American dream, saying, "Where you are right now doesn't have to determine where you'll end up. No one's written your destiny for you. Here in America . . . you make your own future."

The president further invokes patriotism, insisting that "if you quit on school, you're not just quitting on yourself, you're quitting on your country."

He ends by invoking the deity.

Predictably, members of the opposition party denounce the president as a would-be Big Brother using his media clout to establish a cult of personality among America's young people.

Of course, the president wasn't conservative Richard Nixon, Ronald Reagan or either Bush, but liberal Democrat Barack Obama.

Had President Obama's back-to-school speech been given by a Republican president, liberals from teachers unions, universities and our major dailies would castigate it as a reactionary effort to "blame the victim," denigrating the poor for not pulling themselves up by their bootstraps. Liberals would denounce the president's call for students to respect their elders, rather than question authority.

So why is it that liberals, save for a few Marxist professors, defended the president's talk? Why did conservatives, save for the plucky Newt Gingrich, attack it?

Perhaps our reactions to Obama, even when he does something as mundane as asking kids to do their homework, say more about us than about the president.

Politics has always been more about cultural identity and group loyalty than rational calculation. If someone is from our team, we back their message, even if it contradicts our values.

As the old saying goes, only Nixon can go to China. Increased partisan polarization makes that doubly true. Today, only a liberal African-American president like Obama can urge disadvantaged children to work hard in school without being accused of racism, or worse.

Indeed Obama has done any number of conservative things, such as adding troops in Afghanistan, embracing Dick Cheney-style preventive detention for terror suspects and backing school standards, without losing support from his allies on the left or gaining any from the right.

It was much the same for Obama's hapless predecessor. As political scientists Jeff Cohen and Costas Panagopoulos wrote in a book I just edited on the Bush presidency, voters' perceptions of the economy under President George W. Bush reflected their partisan loyalties rather than objective economic conditions. Democrats failed to give Bush credit even when the economy did well; Republicans failed to fault him even when unemployment spiked.

This basic reality determined how Bush governed. As an acquaintance who worked in the Bush White House observed, Bush made few efforts to reach out to Democrats, in part since by 2003 his team had concluded that Democrats would oppose the administration no matter what it did. The Obama team has already reached the same conclusion about Republicans.

The bad news is that divorcing political judgments from policy reality means politicians have more incentive to organize their own partisans, and less to govern well.

For that, we can't blame the politicians. In the words of Cassius, "The fault, dear Brutus, is not in our stars, but in ourselves."

Robert Maranto is 21st Century Chair in Leadership in the Department of Education Reform at the University of Arkansas. His most recent book is "Judging Bush" (Stanford University Press, 2009). E-mail: rmaranto@uark.edu.