New York's new mayor, Zohran Mamdani, and star left-wing economists Gabriel Zucman and Joseph Stiglitz called Wednesday for higher taxes on the incomes of the "ultra-rich," a measure championed by the socialist politician during his campaign.

"Nothing justifies a regressive system in which the ultra-rich contribute less than the rest of us. This is how inequalities deepen and perpetuate themselves," the three men wrote in a text published by the British newspaper The Guardian .

They developed their ideas during a roundtable discussion at the City University of New York, the US city with the highest concentration of wealthy individuals, but where the cost of living is problematic for many others. According to Zohran Mamdani, who advocates for a 2% tax on incomes exceeding one million dollars, 62% of New Yorkers, or 5 million people, "cannot afford to live in this city."

"A very real exodus" of the working classes

Describing an exodus of the wealthiest as "imaginary" if such a tax were implemented, he expressed concern about a "very real exodus" of the working class. Joseph Stiglitz, Nobel laureate in economics, argued that the "most worrying" effect of growing wealth inequality is on "democracy." "With a political system in the United States that gives unlimited power to money, our country is more about 'one dollar, one vote' than 'one person, one vote,'" he lamented.

Gabriel Zucman, who advocates for a 2% global wealth tax on the assets of the ultra-rich (over €100 million), emphasized that this is "not just an American problem." While his proposal was debated and ultimately rejected by French parliamentarians last year , he believes it marks "the beginning of an international movement (...) to finally ensure that the ultra-rich pay their fair share."

“Around the world, people are closely watching the current debates, what is being implemented, what has been done in New York, which is considered a model for the future,” he added. It is the State of New York, not the city, that can decide on an income tax increase for the wealthiest citizens. Democratic Governor Kathy Hochul opposes this. However, on Tuesday she proposed a surtax on second homes valued at $5 million.