"The Income Gap: How Much Is Too Much?"

RACHEL MARTIN, HOST:

Last month, President Obama called income inequality and economic mobility, quote, "the defining challenge of our time." Since, as we just heard, President Obama is sure to discuss income inequality this coming week, we wanted to take a closer look at the growing income gap and what that means for economic opportunity.

A recent academic report triggered more debate about the issue and NPR's Yuki Noguchi has more.

YUKI NOGUCHI, BYLINE: There seems to be one point that the right and left seem to agree about. That is that this is the land of equal opportunity more than, as President Obama says, equal outcomes. Still, historically, the country's policies have sought to address both. President Lyndon Johnson's War on Poverty created early childhood education programs and investments in poorer schools. But it also tried to address the income gap by creating social safety net programs like Medicare and food stamps.

And Sheldon Danziger says in the decades that followed, that approach worked. Wages rose for everyone. The economy bounced back quickly from brief recessions. Both of those things, he says, are no longer true about the U.S. economy today.

SHELDON DANZIGER: What's not going to happen is a return to the golden age when a rising tide lifted all boats.

NOGUCHI: Danziger is president of the Russell Sage Foundation, a progressive think tank. He argues that the yawning gap in the income distribution - between the top earners and those at the bottom - is becoming self-perpetuating. He says the rich get richer from investments in the financial markets and secure better educations for their children. Minimum wage and middle-income earners, meanwhile, cannot keep pace; making it less likely their children will have the opportunities to move up.

DANZIGER: The American dream is less robust than the Canadian dream.

NOGUCHI: Children born in Canada and some European countries do, in fact, have a better shot at working their way out of poverty than American kids. But an academic study published last week found that contrary to popular perception, it has not gotten harder to climb the income ladder in the U.S. in the last two decades.

Scott Winship is a fellow at the Manhattan Institute, a right-leaning think tank. He says that study debunks some commonly held misconceptions. Just because a handful of people at the top are making much more money, he says, that does not mean there are greater barriers to climbing the economic rungs.

SCOTT WINSHIP: There's an intuition among a lot of people that income inequality has had a lot of these problematic effects. But when you get into the research that's been done, it's hard to find a reason to worry.

NOGUCHI: Winship says policy should aim to increase access to opportunities to those on the lower rungs of the social ladder. But, he says, narrowing the income gap by taxing the rich more or raising the minimum wage is unlikely to have much of an effect on mobility.

Richard Reeves is policy director for the Center on Children and Families at the Brookings Institution, and he agrees the inequality gap is driven largely by those at the very, very top of the income scale making even more. And the discrepancies, while staggering, benefit a relative handful of those outliers. Which raises the question: How much does income inequality matter if we're talking about a relative handful of people?

RICHARD REEVES: How much does that matter? In a way, I think you're asking the central question of much of current political debate.

NOGUCHI: Reeves says: This is where philosophy meets policy. Some say, those who can make money deserve to be richly rewarded.

REEVES: On the other hand, you can say that other things happen when people are doing that much better than the rest of society - they pull away. They might be able to avoid tax by complicated tax schemes. They may ensure their own children do much better, which I think is a problem, by opportunity hoarding. They may - if you have a political system that allows people with money to have disproportionate political influence - end up shaping the very policies that result in greater levels of income inequality.

NOGUCHI: Reeves says the economy around the world is shifting toward one that heavily favors educated knowledge workers. And that will continue to exacerbate the problem.

REEVES: Policy is running harder and faster just to stand still.

NOGUCHI: And that he says is by no means just an American problem.

Yuki Noguchi, NPR News, Washington.