Gabriel Zucman, of the École Normale Supérieure, is campaigning to tax billionaires. He was invited on Thursday by Brazil to present his work to the G20 finance ministers.
Although an agreement on such a tax is still far away, the subject is not taboo, he says. The same logic can be applied to the taxation of very large fortunes, he adds. He is optimistic about the future of the idea, despite a rise in populism in the U.S.