It has long been known that spurts of rapid economic growth can increase inequality: China and India are the latest examples. But might slow growth and rising inequality - the two most salient characteristics of developed economies nowadays - also be connected?

That is the intriguing hypothesis of a recent study by French economist Thomas Piketty, of the Paris School of Economics. Piketty has done some of the most important work on inequality in recent years.

Taking advantage of the French bureaucracy's precision, Piketty was able to reconstruct the French national accounts over nearly two centuries. The economy from 1820 until World War I - a kind of second ancien regime - had two striking features: slow growth (about 1 percent a year) and an outsize share of inherited wealth, which accounted for about 20-25 percent of GDP.

The link between low growth and the importance of inheritance, Piketty argues, was not coincidental: With inherited wealth yielding 2-3 percent a year and new investment only 1 percent, social mobility was extremely limited and stratification was encouraged.

That began to change with World War I, when growth picked up - a trend that accelerated sharply after World War II. With annual economic growth running as high as 5 percent during the post-1945 boom, inherited wealth shrank to only 5 percent of France's GDP, ushering in a period of relative mobility and equality. Ominously, however, during the past two decades of slow growth, the share of inherited wealth has rebounded to about 12 percent of France's economy. This pattern should be a cause for concern, because annual GDP growth in the eurozone during the past decade has averaged about 1 percent. Similarly, average annual growth in the United States has slowed from around 4 percent between 1870 and 1973 to roughly 2 percent since then.

Joseph Stiglitz, the Nobel Prize-winning economist, also believes that low growth and inequality are interconnected, but he believes that the causal arrow moves in the opposite direction. As he put it in a recent interview: "I think it's inequality that's causing low growth." In his new book, The Price of Inequality, he writes: "Politics have shaped the market, and shaped it in ways that advantage the top at the expense of the rest."

Rent-seeking, the ability of entrenched elites to allocate resources to themselves and smother opportunity for others, invariably leads to a less competitive market and lower growth.There is some support for this argument in Piketty's work: the French economy takes off after World War I and again after World War II, both periods in which the French political system opened up and enacted progressive reforms.

But, according to Ilyana Kuziemko, an economist at Princeton University, there is also evidence that low growth does indeed increase inequality. Public opinion data and experimental research indicate that people (or at least Americans) become less favorable to income redistribution during economic hard times. Gallup polls, for example, show support in the US for reducing inequality falling from 68 percent to 57 percent during the current recession, despite all of the public rhetoric - and evidence - that the top 1 percent of income earners have captured almost all of the gains from economic growth in recent years.

Curiously, hard times may actually trigger among the economy's losers a psychological mechanism known as "last-place aversion". Experimental economists have found that subjects asked to play distribution games become much less generous toward those below them when they are in second-to-last place. They would rather distribute money to those above them on the totem pole than help those at the bottom to surpass them. This finding dovetails with the work of Harvard University's Benjamin Friedman, who argues in The Moral Consequences of Growth: "Economic growth more often than not fosters greater opportunity, tolerance of diversity, social mobility, commitment to fairness, and dedication to democracy." Similarly, lack of growth tends to breed xenophobia, intolerance and a negative attitude toward the poor . "People in the 30th percentile are desperate not to fall into the 20th or 10th percentile," he concludes.

Thus, a slow-growth/high-inequality economy may become a self-perpetuating cycle. But Stiglitz and Piketty both do not think that it must be so. "First of all, the Scandinavian countries, which have the greatest equality, are also among the fastest-growing advanced economies, and take the example of Japan, which has experienced deflation for about 20 years but successfully maintained a decent level of equality and standard of living," Stiglitz argues.

Piketty believes that the key may lie in making a psychological adjustment to a period of slower growth: "We may need to accept the fact that the post-World War II years of 4 percent and 5 percent annual growth were the exception, and that 1 percent annual growth - after allowing for population growth is much more the norm."

Indeed, Piketty argues that our "obsession with growth" merely "serves as an excuse for not doing anything about health, about education, or about redistribution." And it is an obsession rooted very much in the present. "We forget that for centuries growth was essentially zero," he writes. "One percent real growth means doubling the size of your economy every 30 or 35 years."

Piketty sees that as grounds "to be a little optimistic". But, as he suggests, the share of inherited wealth may turn out to be a strong indicator of whether that rate of growth will be enough to ensure greater social mobility and reduce economic inequality.

The author is professor of international journalism at Columbia University/Project Syndicate.