If Donald Trump’s presidency taught anything to scholars of international relations, it is that the psychology of leaders matters a great deal. But that basic truth was one that our mentor and friend Robert Jervis, who passed away on December 9, 2021, had long stressed: in seeking to understand both behavior and outcomes in world affairs, Jervis championed the role of individuals’ perceptions and formative experiences rather than just broad political, social, and economic forces. His brilliant insights reflected a full embrace of the complexity of international politics.

Over the course of six decades, Jervis made landmark contributions to the understanding of the most consequential issues of war and peace: the implications of nuclear weapons, the causes of intelligence failures, the consequences of misperceptions that complicate even the best-intentioned diplomacy. That work was always rooted in the complexities of actual decision-making by real people with quirks and flaws. Although Jervis crafted general theories regarding the political logic of international security, he was invariably quick to note that actual leaders often fail to behave according to that logic. And as much as his general theories, it is Jervis’s appreciation of that disconnect that makes his work so uniquely relevant to some of today’s most important international security and foreign policy challenges—from deterring Russian President Vladimir Putin to curbing Iranian nuclear weapons development to countering threats to peace and stability in the Taiwan Strait. 


Jervis’s early work investigated the importance and complexities of signaling and perception in international diplomacy. In his seminal two first books, The Logic of Images in International Relations and Perception and Misperception in International Politics, Jervis explored how leaders demonstrate that they truly care about an issue and have the capacity to act on their concerns while avoiding exploitation by other actors. His thinking was deeply rooted in psychology, and so he understood that a signal sent is only as good as how it is received. He focused on how leaders interpret the noisy world of international politics, showing persuasively that their cognitive biases, preexisting beliefs, and personal experiences often prove as consequential, or even more consequential, than objective conditions.

Despite being a political scientist, Jervis was an honorary diplomatic historian who carefully validated his theories by researching archival materials and secondary histories to reveal real leaders’ thinking at historically consequential moments. Studying how policymakers think led Jervis to wrestle with questions of reputation and credibility. Since states interact repeatedly with other states and since third parties observe those interactions, leaders must concern themselves with how foreigners view them and their nations: it is the observers of their actions, more than the state or leader in question, that determines credibility. Reputations are by their nature subjective, filtered through perceptions that are subject to cognitive, motivated, and idiosyncratic biases.

Jervis made landmark contributions to the most consequential issues of war and peace.

In exploring the perceptions of a state’s capabilities, willingness to bear pain, intentions, and national interests, Jervis highlighted that different observers may believe different things about any or all of these factors. Allies of any given state may draw different conclusions than adversaries about the meaning of that state’s behavior for future interactions. The fact that international politics is rife with both uncertainty and strategic incentives for deception further complicates these inferences.

Concern about protecting and fostering their reputations often motivates leaders to take bold measures that might otherwise be difficult to explain. Jervis analyzed, for instance, the catalyzing effect of the domino theory on U.S. interventionism during the Cold War. American policymakers believed that if one state fell to communism without a fight, others would soon follow. Scholars routinely derided the domino theory as dangerously divorced from reality. Yet the theory’s psychological underpinnings often generated reality. In fact, the theory was so powerful that it was never truly tested because initial dominoes were rarely, if ever, allowed to fall without a fight. In this sense, the theory was self-negating precisely because anticommunist leaders believed in it so strongly and behaved accordingly—a demonstration of why Jervis’s psychological approach to international relations is essential to understanding of international politics.


Among policy analysts, Jervis is famous for his study of crisis management, coercive diplomacy, and nuclear deterrence. Here, he built on the Nobel Prize–winning game theory of his friend and colleague Thomas Schelling in recognizing that deterrence is a bargain: it requires both a credible threat of punishment if the target behaves in proscribed ways and a credible assurance that the target will not be punished if it complies with the deterrer’s demands. Assurances are not a supplement to deterrence but rather an essential piece of the puzzle (and if one wants to know if the assurances were effective, one must study the target’s perceptions, not one’s own). Yet policymakers routinely fail to understand this lesson. Consider President Barack Obama’s statement that Syrian President Bashar al-Assad “must go” as part of any effort to resolve the Syrian civil war. Once Assad’s demise became an essential negotiating demand of U.S. coercive diplomacy (without assurances made that his personal interests would be protected), he had no incentive to adjust his behavior in ways desired by the United States. The failure to offer credible assurances undercuts deterrence just as much as the failure to level credible threats does.

Jervis saw that finding the proper mix of threats and assurances was never easy but was still essential to preventing crises from escalating into conflict. Indeed, the concept of the security dilemma—in which one state’s efforts to bolster its defensive capabilities are seen as threatening to its adversaries, who respond in kind, leaving both states less secure in a spiral of tensions and mistrust—is deeply rooted in the tensions between credible threats and credible assurances. Jervis’s analysis of this concept formed the basis of what may be the most influential article in the history of international relations theory, his 1978 “Cooperation Under the Security Dilemma.”

Within this theoretical framework, Jervis also considered how weapons technologies, military doctrines, and geography influence the stability or instability of international politics. Technologies and doctrines that give the advantage to early offensive aggression are destabilizing, and those that provide a defensive advantage have the opposite effect, reducing the premium on early aggression while providing time and space for diplomacy. In The Meaning of the Nuclear Revolution, Jervis argued that the two superpowers’ development of second-strike nuclear capability provided the structural conditions for wide-ranging stability during the Cold War. He captured the reality of the situation in plain language: given the nature of nuclear weapons technology and the size and diversity of the Soviet and American arsenals, the condition of Mutually Assured Destruction (MAD) “was a fact, not a policy.” Jervis believed that MAD not only prevented nuclear war but also cast a large and stabilizing shadow over any potential superpower conflict.

With Robert Jervis’s passing, the world has lost one of its most astute observers of international politics.

As long as a credible “slippery slope” from conventional war to nuclear war existed, Jervis argued, the actual balance of conventional and nuclear capabilities was less important—leaders would be loath to exploit tactical advantages at lower levels of violence if it carried a real risk of escalation to strategic nuclear war.

Despite these elegant theoretical conclusions, Jervis was acutely aware that the superpowers’ military postures often ignored the reality of MAD. He spent a good deal of his professional life criticizing the U.S. government for obsessing over nuclear warfighting capabilities and the balance of conventional forces in Europe.

In a sense, The Meaning of the Nuclear Revolution was about what nuclear weapons should mean for strategy and doctrine. Another, less heralded book, Jervis’s The Illogic of American Nuclear Strategy, focused on why and how American policymakers behaved as if MAD could be ignored or wished away. The difference between these two books nicely illustrates the core tension between theory and practice that drove much of Jervis’s work: actual security policies are not made by utility-maximizing actors responding rationally to external pressures but by real human beings who dedicate their careers to protecting their fellow citizens. It was simply too difficult for officials to accept the logic of MAD and target foreign civilians rather than foreign militaries while leaving their own populations defenseless.


In his appreciation for the human side of international politics, Jervis was more than just an academic giant. He was a dedicated public servant who helped the U.S. intelligence community understand why intelligence failures occur and what documents could safely be declassified for general public release. All who knew Jervis recognized not only his intellect but also his integrity and honesty. How else could a former leader of Students for a Democratic Society at the University of California, Berkeley, in the 1960s be entrusted with the security clearances required to carry out this important work?

His brilliant contribution to the field of intelligence studies is also reflected in his extremely influential postmortems on two American intelligence failures: not anticipating the fall of the shah of Iran, in 1979, and flawed assessments of the development of weapons of mass destruction in Iraq leading up to the U.S. invasion, in 2003. The latter review, an unclassified version of which Jervis was permitted to publish, might say the most about his integrity. He wore his political leanings on his sleeve and was refreshingly aware of his resulting biases; a self-described liberal Democrat, he warned students that his political beliefs might affect his analyses. After the invasion of Iraq revealed no large stockpile of WMD and descended into a bloody quagmire, conspiracy theories abounded, based on the assumption that the Bush administration deliberately distorted the intelligence to justify war. After a careful review, Jervis reached the unpopular conclusion—unpopular among fellow academics at least—that flawed intelligence tradecraft by career professionals, rather than partisan politics, accounted for the disastrously wrong intelligence estimates. Jervis was more than just brilliant, dedicated, and prolific; he was also brave.

With Robert Jervis’s passing, the world has lost one of its most astute observers of international politics. “May his memory be a blessing” goes the saying in the Jewish tradition. In this case, by bringing his insights and wisdom to their own work, scholars, policymakers, and engaged citizens can ensure that Jervis’s memory will indeed be a blessing.

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  • THOMAS J. CHRISTENSEN is James T. Shotwell Professor of International Relations and Interim Dean at Columbia University’s School of International and Public Affairs, where he directs the China and the World Program. 
  • KEREN YARHI-MILO is Arnold A. Saltzman Professor of War and Peace Studies and Director of the Saltzman Institute of War and Peace Studies at Columbia University’s School of International and Public Affairs.
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