Joseph S. Nye Jr., an influential figure in shaping American national security policy, who wrote seminal books on foreign affairs, held top jobs at Harvard and in government, and coined the term “soft power” — the idea that America’s global influence was more than its military might — died on Tuesday in Cambridge, Mass. He was 88.

His death, in a hospital, was confirmed by his son Daniel.

Sometimes considered the dean of American political science, Mr. Nye led the John F. Kennedy School of Government at Harvard and held senior jobs in the Carter and Clinton administrations.

His thinking radiated far outside the Ivory Tower: He influenced diplomats and national security officials, and, as a soft-spoken, fatherly figure, he was a mentor to many who made careers in government.

“Joe Nye was a giant: a giant because his ideas shaped the worldviews of multiple generations of policymakers — but even more so a giant because his personal touch shaped our life choices,” Jake Sullivan, the national security adviser to President Joseph R. Biden Jr., said in a text message.

Mr. Nye developed the concept of soft power in the late 1980s to explain how America’s ability to get other nations to do what it wanted rested on more than the power of its military or economy; it also derived from American values.

“Seduction is always more effective than coercion,” he explained in a 2005 interview. “And many of our values, such as democracy, human rights and individual opportunity, are deeply seductive.”