Dr. Schelling, left, receives the Nobel Przie from King Carl XVI Gustaf of Sweden in Stockholm in 2005. (Anders Wiklund/Scanpix via Reuters)

Thomas C. Schelling, a game theorist who received the Nobel Prize in economics for insights that were credited with lessening the nuclear threat during the Cold War — and with helping explain why some neighborhoods are segregated, why smokers struggle so mightily to quit, and why people send holiday cards even when they would rather not, died Dec. 13 at his home in Bethesda, Md. He was 95.

The cause was complications from a hip fracture, said his son Daniel Schelling.

Dr. Schelling’s career took him from government to academia and across disciplines, including economics, foreign policy, urban planning and psychology.

Trained as an economist, he came of professional age as an adviser and analyst during the Truman administration and grew fascinated by negotiation during the Cold War confrontation between the United States and the Soviet Union. He later taught for three decades at Harvard University before retiring in 2003 from the University of Maryland.

Dr. Schelling was best known for his application and elaboration of game theory, the mathematical study of decision-making amid conflict. For policymakers engaged with the Soviets and for experts who sought to analyze the standoff, his writings — particularly the book “The Strategy of Conflict” (1960) — became field guides for averting a nuclear crisis.

Dr. Schelling looked upon war as bargaining, in which competing sides are influenced by incentives and deterrents, promises and threats, and the abundance or dearth of information. Among his insights was the idea that a party to a conflict may make itself stronger by reducing its own options.

For example, a president limited by legislative oversight may be stronger at a negotiating table than a president with no oversight. The adversary knows that the president with limited authority is not fully free to act as he or she pleases. Therefore, the adversary cannot reasonably demand as much as he or she might want.

To improve communications between the United States and the Soviet Union, he was reportedly among the government advisers who recommended the “hotline” connecting Washington and Moscow that was established in 1963.

Dr. Schelling also demonstrated “that the capability to retaliate can be more useful than the ability to resist an attack, and that uncertain retaliation is more credible and more efficient than certain retaliation,” the Royal Swedish Academy of Sciences observed in announcing Dr. Schelling’s Nobel Prize. “These insights have proven to be of great relevance for conflict resolution and efforts to avoid war.”

The citation honored Dr. Schelling and the Israeli economist Robert J. Aumann, who shared the economics prize in 2005, with “having enhanced our understanding of conflict and cooperation through game-theory analysis.”

(Asked at the time by the Baltimore Sun whether he considered himself an economist, Dr. Schelling quipped that although much of his work lay outside the field of economics, as it was strictly defined, he “could still pass the Ph.D. examinations.”)

Dr. Schelling was drawn to game theory in part because of its wide-ranging applications. It “can be used,” he observed, “if you try to discipline a child or deal with employees, or employers or neighbors.”

In the 1970s, he used game theory to show how some neighborhoods became racially segregated, even when their residents say that they do not object to integration.

“Whites and blacks may not mind each other’s presence, may even prefer integration, but may nevertheless wish to avoid minority status,” he wrote in “Micromotives and Macrobehavior,” first published in 1978. “Except for a mixture at exactly 50:50, no mixture will then be self-sustaining because there is none without a minority, and if the minority evacuates, complete segregation occurs.”

The concept of a “tipping” point, as elaborated by Dr. Schelling, was later popularized by best-selling author Malcolm Gladwell.

Dr. Schelling explored not only conflicts between warring parties, but also those within oneself, such as the battle fought by a smoker who promises to stop the habit, only to continually indulge in one “last” cigarette.

“Just as it may be easier to ban nuclear weapons from the battlefield in toto than through carefully graduated specifications on their use, zero is a more enforceable limit on cigarettes or chewing gum than some flexible quantitative ration,” he wrote in “Choice and Consequence: Perspective of an Errant Economist” (1984).

He confessed that he could personally attest to the validity of the principle, having unsuccessfully tried to quit tobacco by allowing it to himself after an “evening meal.” “It stimulated a lot of token sandwiches,” he wrote.

Thomas Crombie Schelling was born in Oakland, Calif., on April 14, 1921. His father was a Naval officer, and his mother, a former teacher, was a homemaker. He received a bachelor’s degree in economics from the University of California at Berkeley in 1944 and, after working in Europe for the Marshall Plan, a PhD in economics from Harvard in 1951.

Before being awarded the Nobel, Dr. Schelling was not overwhelmingly recognized among economists. “Perhaps because he stayed away from the Journal of Advanced Economic Gobbledygook, Schelling’s pathbreaking conceptual work received less attention from his home discipline that it deserved,” Richard Zeckhauser, a former student and colleague, wrote in a tribute to Dr. Schelling in 1989.

He did, however, receive attention from filmmaker Stanley Kubrick, who read Dr. Schelling’s 1960 article “Meteors, Mischief and Wars” analyzing several novels that conjured up the outbreak of nuclear war.

One of those novels was “Red Alert” by Peter Bryant, later adapted by Kubrick into the Cold War-satire “Dr. Strangelove or: How I Learned to Stop Worrying and Love the Bomb” (1964). Dr. Schelling acted as a consultant on the film.

In the movie, the Soviets deploy a “doomsday device” programmed to detonate in the event of an attack. Speaking to the New York Times, Dr. Schelling enunciated in terms of game theory the film’s central joke: “One obvious point in the Strangelove movie was that the Soviet doomsday thing was not a deterrent . . . when the other side did not know in advance that it existed.”

Dr. Schelling’s first marriage, to Corinne Saposs, ended in divorce. Survivors include his wife of 25 years, Alice Coleman Schelling of Bethesda; four sons from his first marriage, Andrew Schelling of Boulder, Colo., Tom Schelling of Ashland, Mass., Daniel Schelling of Salt Lake City and Robert Schelling of Putney, Vt.; two stepsons, David Coleman of Mountain View, Calif., and Robert Coleman of Portland, Ore.; a sister; 12 grandchildren; and three great-grandchildren.

Dr. Schelling said that he was “by temperament” an optimist. But even he remarked, in his Nobel lecture, that “the most spectacular event of the past half-century is one that did not occur. We have enjoyed 60 years without nuclear weapons exploded in anger.”

In a career devoted to such consequential matters, he found time to extract meaning from more mundane events, such as the custom of exchanging holiday cards. No matter how overwhelmed many people may be with preparations for festivities, no matter how little they may wish to write, address, stamp and send the cards, they continue the tradition.

It was, he said, a matter of game theory (if not a point of holiday cheer).

“Sensible people who might readily agree to stop bothering each other with Christmas cards,” he wrote, “find it embarrassing, or not quite worth the trouble, to reach such agreement.”