Inequality for Dummies - NYTimes.com Inequality is in. The president, you have probably heard, has declared income inequality to be "the defining challenge of our time." Except he didn't quite, but we'll get to that. Politicians, pundits and activists on the left have seized on the president's words, along with the rising fortunes of progressive idols Elizabeth Warren and Bill de Blasio, to refute the apostles of austerity (mostly Republicans these days) and lay down early populist markers for the 2016 elections. Liberals of a more centrist bent - notably the former Clintonites at the Third Way think tank - have refused to join the chorus and been lashed by fellow Democrats for their blasphemy. Senator Warren has suggested that liberals who disagree with her are in the pocket of Wall Street. Third Way executives took to the op-ed page of The Wall Street Journal to accuse the populists of indulging a " "we can have it all" fantasy." If you traffic in opinions, as a pro or an amateur, you'd better have opinions about inequality. And so I set off into the intramural battlefield to see what's up. For starters, economic inequality is manifestly real, growing and dangerous. The gulf between the penthouse and the projects is obscenely wide. Obama cited some of the startling numbers: The top 10 percent of Americans used to take in a third of the national income. Now they gobble up half. The typical corporate C.E.O. used to make 30 times as much as the average worker. Now the boss makes 270 times as much as the minion. Many factors have led to this trend, including the offshoring of work to low-paid foreign labor, the automation of everything from manufacturing to meter-reading, a tax code that allows the accumulation of riches at the top, the slow growth of educational attainment, the demise of strong unions, a collapse of the social contract. The alarming thing is not inequality per se, but immobility. It's not just that we have too many poor people, but that they are stranded in poverty with long odds against getting out. The rich (and their children) stay rich, the poor (and their children) stay poor. President Obama's speech on Dec. 4, widely characterized as his inequality speech, was actually billed by the White House as a speech on economic mobility. The equality he urged us to strive for was not equality of wealth but equality of opportunity. A stratified society in which the bottom and top are mostly locked in place is not just morally offensive; it is unstable. Recessions are more frequent in such countries. A widely praised 2012 book, "Why Nations Fail," argues that historically when the ruling elites have pulled up the ladder and kept newcomers from getting a foothold, their economies have suffocated and died. "The most pernicious fact of inequality is when it translates into political inequality," said Daron Acemoglu, a co-author of the book and a Massachusetts Institute of Technology economist. That means our democracy ceases to function because some people have so much money they command greater power. The rich spend heavily on lobbyists and campaign donations to secure tax breaks and tariff advantages and bailouts that perpetuate their status. Not only does a dynamic economy stagnate, but the left-out citizenry becomes disillusioned and cynical. Sound familiar? The left-left sees economic inequality as mainly a problem of distribution - the accumulation of vast wealth that never really trickles down from on high. Their prescription is to tax the 1 percent and close corporate loopholes, using the new revenues to subsidize the needs of the poor and middle class. They would string the safety net higher: expand Social Security, hold Medicare inviolate, extend unemployment insurance, protect food stamps, create more low-income housing. They would raise the minimum wage. The center-left - and that includes President Obama, most of the time - sees the problem and the solutions as more complicated. Yes, you want to provide greater security for those without independent means (see Obamacare), but you also need to create opportunity, which means, first and foremost, jobs. Yes, you can raise taxes on the rich, but you don't want to punish success. "You want to increase social mobility by providing an opportunity for the bottom to become rich, not forcing the rich to become poor," said Acemoglu, who aligns more with the center than with the populists.