Thomas Schelling originally worked in the field of economics, focussing on international political economy, trade policy, and tariffs.
In the 1950s and 1960s, he was associated with the RAND Corporation and its leading lights, including Herman Kahn, Bernard Brodie, and Albert Wohlstetter.
Like many of his contemporaries, Schelling thought that the American military establishment was intellectually immature. From the late 1950s onwards, he thus became interested in applying ideas from the social sciences to strategy.
His two most famous books, The Strategy of Conflict (1960) and Arms and Influence (1966), deal with conflict and cooperation in the nuclear age. It was for this work that he was awarded the Nobel Memorial Prize in Economic Sciences in 2005.
According to Schelling, the direct use of force is incredibly risky in the era of thermonuclear weapons and intercontinental ballistic missiles (ICBMs) because the mutual vulnerability that exists between nuclear powers makes meaningful military victory almost impossible.
As a result, states must use the threat of force—“latent violence”, as Schelling puts it—to advance their interests. For such a threat to be effective, it must be accompanied by an assurance that an adversary can “avoid pain or loss if s/he does comply.”
These threats can be divided into two categories.
First, deterrence. This is a threat that is intended to prevent an adversary from doing something. For instance, State A threatens to do X if State B does Y. In this scenario, State A is essentially reactive, with the onus of action on State B.
A good example of this is the stationing of American and British troops in West Germany during the Cold War to deter a Soviet invasion. The nuclear ‘balance of terror’ also comes to mind.
Second, compellence. This is a threat intended to coerce an adversary to do something. For instance, State A does X to make State B do Y.
President John F. Kennedy’s decision to blockade Cuba in October 1962 falls under this rubric, as does Operation Rolling Thunder, a graduated aerial bombing campaign conducted by the United States Air Force during the early stages of the Vietnam War.
For both deterrence and compellence to be effective, states must clearly communicate their expectations and ensure that their threat appears credible. The state being threatened must also fear punishment more than any other alternative, and there has to be a clear promise implicit in the threat.
In his seminal book, On War, the Prussian strategist Carl von Clausewitz famously observed that “[w]ar is the continuation of politics by other means.” In other words, the use of armed force only makes sense if it serves a higher political purpose.
In view of Clausewitz’s dictum, with which few can find fault, Schelling’s notion of the “diplomacy of violence” was and still is a practical attempt to explain and exploit the evolving utility of force in the nuclear age.
There are, of course, exceptions to the rule. While compellence worked during the Cuban Missile Crisis, it failed to achieve the desired effects during the Gulf Crisis of 1990-1991. And there are certainly questions as to whether Schelling’s concept is useful when analysing Western attitudes and responses to contemporary problems, such as the Iranian and North Korean nuclear weapons programmes.
Still, exceptions remain just that. It falls upon some young upstart to make a new rule. Until then, serious students of strategy have no choice but to contend with Schelling’s ideas.