Mathematicians are threatening to boycott the field’s largest, most prestigious gathering this summer if it takes place in the U.S., as currently planned.

Every four years since the turn of the twentieth century, the International Congress of Mathematicians (ICM) has brought together mathematicians from all over the world to share the latest breakthroughs and plot the field’s future. Famous speeches delivered at the congress have gone on to redefine entire subfields of math. The ICM is also where math’s most hallowed prize, the Fields Medal, is awarded. This July, the ICM is slated to take place in Philadelphia—the first time in 40 years that it’s been held in the U.S.

Now a petition to move the event elsewhere is circulating among mathematicians. It cites the recent American military actions in Venezuela and Iran, the suspension of visas from 75 countries and the continued presence of federal Immigration and Customs Enforcement (ICE) agents across major U.S. cities as contrary to the ICM’s goal of fostering “a sense of international unity amongst mathematicians.”

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As of this writing, more than 1,500 mathematicians have signed the petition, which states that they plan to boycott the event if it isn’t moved outside the U.S. The list of signatories includes many of the field’s most prominent names, more than 50 of whom have spoken at previous congresses.

The petition cites the 2022 decision by the ICM’s organizing body, the International Mathematical Union (IMU), to move the last congress out of Saint Petersburg, Russia, in response to the country’s full-scale invasion of Ukraine earlier that year. The event was moved mostly online, with a small in-person awards ceremony held in Helsinki, Finland.

“Holding the ICM in the United States, after it started two illegal wars, represents a double standard, given that, practically immediately after Russia invaded Ukraine, the ICM in Russia was canceled,” says Michael Harris, a mathematician at Columbia University. Harris is a scheduled panelist for the conference, though he is listed by the petition as an ICM speaker who shares its values.

When contacted by Scientific American, representatives of the IMU as well as the Simons Foundation, which is providing much of the conference’s funding, did not provide comment for publication.

The petition follows months of trepidation about the congress within the math community. “You do not get 1,500 signatures in 10 days without having many, many mathematicians already registering their complaints to their professional societies and to the ICM organizers,” says Ila Varma, a mathematician at the University of Toronto and one of the petition’s co-authors.

In January—before the developments in Venezuela and Iran—the French Mathematical Society (SMF) announced that it would skip the event (France is a mathematical powerhouse, with more Fields Medalists than any country except the U.S.).

“The whole world has watched the events in various American cities and on American campuses. The French are not used to this degree of violence,” says mathematician Isabelle Gallagher, SMF’s current president. Gallagher cites the concerns of the society’s members about travel to the congress. “We were also thinking of our colleagues from other countries—specifically, Global South countries.”

Following SMF’s decision, other mathematical societies and organizations declared their intention to attend. The groups acknowledged concerns voiced by their own members but overruled those objections based on the international spirit of the event.

“International openness and collaboration are essential to mathematical progress,” wrote Ravi Vakil, current president of the American Mathematical Society (AMS), in a February 19 statement. (The AMS is not involved in organizing the ICM.) This year’s ICM, the statement continued, “will powerfully demonstrate the importance of these civilizational values.”

“A lot of what we’re seeing currently has echoes from the past experience of American involvement in International Congresses of Mathematics,” says Michael J. Barany, a historian of mathematics at the University of Edinburgh. Some mathematicians called for a boycott of the 1950 ICM, held in Cambridge, Mass because a number of their peers with perceived communist leanings had difficulty obtaining visas to attend, Barany wrote in a historical article for the April issue of the Notices of the AMS.

Internationalism as a movement, Barany says, has always meant collaboration—and competition—among distinct nations. Like the modern Olympics and other products of the same era, the ICM has never been divorced from those nations’ external conflicts.

“There’s always a point where the desire to include and to represent comes up against the limitations of borders and political contexts and resource constraints,” he says. “One of the recurring lessons—and this is not at all unique to mathematics—is that internationalism is always about compromises.”

What mathematicians have to decide—in any given historical moment—is which compromises they’re comfortable with. “The petition is really strong evidence that what’s being asked of mathematicians for this particular event is just too much,” Barany says.

Varma hopes the petition will encourage mathematicians to exercise their collective voice. “We have these amazing global connections, and we also have influence on governments,” she says. “This power is important to all of society, not just our academic communities.”

But with the July event fast approaching and no response yet from the ICM’s organizers, it remains unclear what the petitioners can wield that power to achieve. “It’s one of the most successful actions of its kind among mathematicians,” Harris says. “But then the question is: What do they want to do with it?”