Tonight, at the Metropolitan Museum of Art, Philippe de Montebello will make the case that museums should continue to acquire antiquities, even when they have imperfect knowledge of an object’s provenance. Mr. de Montebello, the museum’s director, is repeating a lecture he first gave two weeks ago, in which he argued that the law and public opinion have swung too far in favor of the rights of cultural patrimony, and thus against the cosmopolitanism that created the encyclopedic museum epitomized by the Met.

With the Italian authorities coming off the triumph of their recent deals with the Met and the Museum of Fine Arts in Boston, and the trial of the former J. Paul Getty Museum curator Marion True ongoing in Rome, Mr. de Montebello’s resolute defense of museums’ rights may not shift the tone of the conversation on cultural property much, at least not right now.

Among those not convinced by his argument is the DePaul University law professor and expert in cultural heritage law Patty Gerstenblith. “I think it’s an argument of the past,” she said of the notion that a museum’s primary goal is to acquire and display objects regardless of their background. “I don’t want to say that Mr. de Montebello is the only person in the museum world who believes that, because I think there are others who agree with him, but those numbers are dwindling.” She also objected to the opposition of cultural patrimony and cosmopolitanism. “When an object comes on loan with its full historical background, I think that is true cosmopolitanism,” she said.

But Mr. de Montebello is not alone in finding today’s cultural patrimony laws too extreme. “To some extent, I think he’s right,” a lawyer at Flemming Zulack Williamson Zauderer LLP, Dean Nicyper, said. If fully enforced, he said, the current patrimony laws in Italy and Egypt –– under which all artifacts taken out of the ground after a certain date are state property –– would be harmful not only to museums but to the countries of origin themselves, which would be saddled with the burden of keeping all these objects.

If there is progress in stemming the illegal antiquities trade, “the pendulum will start to swing back a little bit,” Mr. Nicyper predicted. “It’s in everybody’s best interest, even the countries of origin, to allows some trade in these materials. It’s to their benefit that this material continue to circulate, that people be able to see it in other countries, maybe even through private ownership,” he said. “If the looting gets under control, I think people will start to back away and see some benefit in commerce.”

Mr. de Montebello also has allies in the academic world, among those who oppose the Archaeological Institute of America’s position on publications — that scholars should not publish on materials without clear provenance.”If we didn’t have unprovenanced materials published, then 80% of our history of Mesopotamia would be missing,” a Harvard professor on the archeology of Israel, Lawrence Stager, said. “We wouldn’t have the Dead Sea Scrolls.”

Mr. Stager and more than 100 other academics have signed a “statement of concern” on the publication of unprovenanced artifacts, which is posted on the Web site of the Biblical Archaeology Society. The statement argues that, while some objects lose much of their meaning when they are looted, many do not: “[L]ooted objects, especially inscriptions, often have much of scholarly importance to impart.”

While Mr. de Montebello wraps both patrimony and publications policy into his wide-ranging lecture, the scholars’ statement makes clear that they are staying out of the former issue.

“The questions we deal with here are quite apart from the issues currently engaging the media and the public regarding patrimony laws and repatriation,” it reads. “On the repatriation issues, we express no view.”

Mr. de Montebello, on the other hand, has strong views about what he sees as the now temporarily triumphant forces of sectarianism, to which the Enlightenment museum is opposed. “We must and will remain true to our mission: to acquire, preserve, and study works of art,” he says toward the close of the lecture. “In every museum, ladies and gentleman, are the memoirs of mankind.”