The French economist Thomas Piketty argues that billionaires should be taxed heavily as a way of dealing with a growing economic inequality that he sees as harmful for both society and the economy.CreditFred Dufour/Agence France-Presse — Getty Images

MUMBAI, India — Many people in the room were seeking Thomas Piketty’s attention, but what caught his eye was a small photograph of Bill Gates in a newspaper. “My friend,” he said with a chuckle.

In his recent, celebrated book, “Capital in the Twenty-First Century,” Mr. Piketty, a French economist, argues that billionaires should be taxed heavily, as a way of dealing with the growing inequality that he sees as being as harmful for the economy as for society. Mr. Gates, he said, had wished to meet him, but invited him “to another planet,” by which Mr. Piketty meant someplace outside Europe. “So we Skyped.”

Yet, Mr. Piketty seemed happy to be on another planet last week, visiting Mumbai for a major cultural event, Times Litfest, where he gave a lecture on India as a vastly unequal place. Afterward, he was mobbed by fans, some of whom introduced themselves by way of the American universities they had attended. “Harvard,” one man said. “Harvard,” the man’s wife, too, said.

After he fled to the authors’ lounge, Mr. Piketty told me that he found the elite of India “hypocritical” for urging their government to address inequality by pouring resources into economic development, like building infrastructure or helping selected industries. This is self-serving, he says, and only increases the gap between the rich and the poor. In his opinion, governments should find the means to invest more in social welfare, like primary education and health care.

Before the world wars, he said, “the French elite used to say the same things that the Indian elite now say, that inequality would be reduced with rising development.” But after the wars, he said, the French began to see that direct investment in welfare was the way forward.

“I hope the Indian elite learn from the stupid mistakes of the other elites,” he said. “Learn from history.”

India is just emerging from what many regard as a catastrophic experiment in a type of socialism, the sort that economists like Amartya Sen, the Nobel laureate, say was not socialism in the first place, because it neglected health care and primary education. What the Indian elite learned from that history was to fear and loathe the idea of the welfare state.

In 1991, India reached the nadir of an economic crisis that forced it, in exchange for a financial rescue from the International Monetary Fund, to begin liberalizing its economy along the free market lines that were championed then by Washington. In the years that followed, the rich and the educated benefited the most, though the poor are better off today than they were before those changes.

Having prospered in recent decades, the Indian elite have faith in this economic model. But there is also a wide acceptance that India’s inadequate investments in education and health are holding the nation back.

“The problems India is trying to solve are problems other countries are trying to solve,” Mr. Piketty had said during his lecture. “India is trying to solve very complicated problems.”

Mr. Piketty sees the harmful effects of inequality behind many of the world’s problems today. After the recent attacks in Paris, he said that gross inequality in the Middle East might have contributed to terrorism, though that could not be the only factor. It cannot explain why India’s 180 million Muslims, most of them poor, have so far been a moderate population. Or why so many militant leaders, like Osama bin Laden, often emerge from the economic elite, or at least from the middle class.

“The reasons for terrorism are complex,” he told me.

Mr. Piketty himself is a rich man now, his book having sold more than a million copies. Has that led him to acquire any new sympathies for the rich?

“I pay 60 percent as tax,” he said. “I would like to pay 90 percent.” He grew a bit thoughtful and said, “I would like to pay 95 percent.”