New York Times columnist and author Thomas Friedman explained Monday evening why he is a “frustrated optimist” about America’s future.

The three-time Pulitzer Prize winner packed roughly 200 listeners into the Whitney Humanities Center auditorium as he discussed the thesis of his recent book written with co-author Michael Mandelbaum, “That Used to Be Us: How America Fell Behind in the World It Invented and How We Can Come Back.” Though Friedman voiced his impatience with what he views as a decade of squandered opportunity in the nation, he also expressed cautious optimism that America will overcome the modern challenges it faces.

The nation’s last 10 years marked the “worst decade in modern American history,” Friedman said, because the United States abandoned the factors that brought it success during the 20th century: robust education of citizens, investment in infrastructure and innovation, the world’s most open immigration policy and effective regulation of national finance.

“We have seen a country with enormous potential fall into the worst sort of decline, a slow decline,” Friedman said. “It is just slow enough for us not to drop everything and pull together to fix what needs to be fixed.”

Friedman said the nation’s decline strikes him as worrisome because of the issues America faces today — particularly the challenge of competing with other nations in a globalized world and an increasingly digital era. Given the salient events that rocked the nation over the past decade, Friedman said it has been easy to miss a global transition from the “connectivity” of the desktop computer to the “hyper-connectivity” of social networks and mobile devices.

Though Friedman claimed the world had become a tightly-knit global community in his 2005 book “The World is Flat,” he admitted Monday that he never anticipated today’s ongoing technological revolution.

“When I was out there [six years ago] saying the world was flat, Facebook didn’t exist, Twitter was a sound, the cloud was still the sky, 4G was a parking place out there and applications were what you sent to Yale,” Friedman said to laughter from the audience. “For most people, Skype was a typo.”

While many think that China will dominate the 21st century, Friedman said one of the reasons he wrote his newest book was so no American would believe that the United States will decline further in the decades ahead. America will find success, Friedman said, by addressing the national debt and returning to the factors of success that led to its prosperity in the previous century.

“We had a formula for success, and it can still work,” he said. “The history books we need to read are our own.”

Four audience members interviewed after the talk seemed to share Friedman’s cautious optimism about America’s future.

“He did a good job of laying out both the problems in America and the reasons for optimism,” Chris Watson ’14 said. “We have our work cut out for us.”

Others felt that Friedman underestimated the difficulties America will face in today’s global community. Davis Zaunbrecher DIV ’13 said Friedman seemed to undersell how much the country has to overcome.

The talk was co-hosted by the Yale Center for the Study of Globalization and the Whitney Humanities Center.