The nuclear weapons debate in the United States can be deconstructed a variety of ways, characterized by competing schools of thought: What goals should (and should not) be served by the possession of nuclear weapons, and how should they be prioritized? Is nuclear disarmament even feasible? How do we measure the adequacy of US nuclear weapons to support accepted national goals? What is “deterrence stability,” and what is required to attain it? These are just some of the many questions we face, and the competing schools of thought offer different answers. There are, however, some basic unifying features within each school—and some deep fissures between each different school—the understanding of which can help to explain each position.
One characteristic feature is the long-standing fissure that separates the “realist” and “idealist” traditions in the study of international relations. (The ancient Greek historian Thucydides was an early voice of realism in his description of the world: “The strong do what they can and the weak suffer what they must.”) The conceptual differences between realists and idealists often show through with regard to nuclear weapons and deterrence. Consequently, it is important to understand that divide properly.
Unfortunately, some commentators have attempted lately to critique the realist position without understanding how it applies to questions of nuclear weapons and deterrence. Their contention is that the self-declared realist camp is characterized by pretenders who falsely claim to see the world as it is. In fact, the argument continues, these pretenders “parade their toughness” in support of US nuclear modernization in the naïve belief that leaders will always behave rationally and thus that nuclear deterrence is foolproof.
However, the critique continues, this realist belief in the consistent rationality of leaders—and thus the predictable workings of deterrence—is betrayed by evidence that leaders will not always think and act rationally. So-called realists, therefore, are not true to actual hard evidence regarding leadership behavior and nuclear deterrence, and their support for nuclear deterrence is built on naiveté. They are “more like religious fanatics with a misplaced faith,” who ignore the plentiful real-world evidence that leaders are not reliably rational decision-makers and that nuclear deterrence can fail. According to this argument, “True realists seek practical alternatives” to deterrence, and the real question is how self-declared realists can be so foolish as to continue to believe against all evidence that leaders are consistently rational and deterrence fully reliable. Accordingly, these critics ask: “Why have nuclear ‘realists’ clung to rationality so long? Why do they continue to insist that it is the cornerstone of nuclear deterrence, when humans are so obviously not that rational?”
But this critique of realists is fundamentally flawed. In actuality, consistent realists do not believe that all leaders will behave according to rational decision-making all the time, nor that deterrence is therefore predictably reliable as a consequence. Instead, realists have for decades recognized that deterrence is fallible for a variety of reasons, such as the wide variety in human perception and decision-making, and the considerable variability in interpreting what constitutes rational and reasonable behavior. Since the 1980s, for example, many of my books and articles have emphasized precisely these points and the historical evidence supporting them. Indeed, to claim that one knows that deterrence will function predictably and reliably in practice is fallacious because the contributing factors are so many, divergent, and often opaque.
Even the most astute observers will not have complete or enduring answers to the most basic questions of deterrence. For example, no one can claim to know with precision and confidence who are the leaders to be deterred, what type of threat will deter them, and how a deterrent threat can be communicated to them without any distortions that undercut the message. Are they even susceptible to deterrence? How do they measure costs and benefits? How will their worldview or culturally-shaped behaviors and thought patterns affect their decision-making? There are literally dozens of additional, comparable questions that would have to be addressed fully and reliably for deterrence to be so predictable.
To presume that anyone can answer these questions reliably is beyond unrealistic, it is utopian. This inadequacy of human beings to predict the functioning of deterrence with precision is not a matter of employing better analysts, refining a model, or adjusting a methodology. Instead, it is a consequence of the fundamental limitations on our knowledge with regard to the prediction of human decision-making and behavior. (And to add to the complexity, deterrence involves the decision-making processes of potentially unfamiliar foreign leaderships over unknown stakes in stressful, unfamiliar circumstances.)
Ignoring the humans behind the equations.The problems in predicting human behavior were elucidated well by Emanuel Dermann, a physicist-turned-Wall Street “quant.” In his book, Models Behaving Badly, Dermann noted that humans are “agents who value assets based on their ephemeral opinions … In human affairs, history matters, and people are altered by every experience … It’s not only the past that leaves its trace on humans. In physics, effects propagate only forward through time, and the future cannot affect the present. [But] in the social sciences the imagined future can affect the present, and thereby the actual future too.” He also drew attention to the fact that, “There are no isolated social systems on which to carry out the repeated experiments the scientific method requires, and so it is hard to study the regularities that might reveal the putative laws that govern them.”
Dermann was writing about decision-making in the field of finance, but his warnings apply equally well to deterrence. He rightly concludes that those who claim the capability to make accurate and precise predictions are pretenders who “whistle in the dark” and “ignore the humans behind the equations.”
These limits and their implications are not ignored by realists as some mistakenly claim. Those I call “consistent” realists fully acknowledge them; to do otherwise is to deny reality. I, for one, gladly accept the label of “realist”—and yet have been identified as “the leading deterrence pessimist of our day.” Perhaps so, but deterrence realist is more appropriate.
The point here is that the recognition that leaders do not always act rationally or reasonably—and that deterrence consequently is fallible—is not new or ignored by realists. Neither does it poke a hole in the realists’ rationale for nuclear deterrence. Those who often claim the utopian capability to confidently predict when nuclear deterrence will work often do so as part of their narrative in favor of deep US nuclear force reductions. There are literally hundreds of examples of such claims. (For typical examples, consider the following statements: “Deterrence today would remain stable even if retaliation against only 10 cities were assured.” And “No current or conceivable future threat requires the United States to maintain more than a few hundred survivable warheads.”)
Of course, the authors of such statements do not know that 10 or “a few hundred” weapons will be adequate for deterrence, now or in the future. Such knowledge cannot exist absent omniscience, because leadership perceptions, decision-making, and behavior are so variable. To take just one potentially pertinent factor among the hundreds in the functioning of deterrence, a given number of weapons does not equate to a predictable deterrent effect, regardless of whether that number is very low or high. Confident claims that deterrence will work reliably at some proffered lowest number of nuclear weapons may help make an argument sound prudent, but such predictions are, as Dermann suggests, whistling in the dark. Those who promise the predictable working of deterrence almost invariably are found among those arguing in this way for “Minimum Deterrence.”
A new world order? In fact, the fallibility of deterrence creates a challenge for both idealists and realists. If nuclear deterrence is fallible, is not the continuing possession of nuclear weapons dangerous? Shouldn’t all reasonable leaders agree that the safest alternative is nuclear disarmament? Isn’t zero the only practical alternative?
The usual idealist answer is “yes,” and so idealists correspondingly posit a fundamental change in the international order that enables nuclear disarmament, such as the establishment of a global collective security organization or the emergence of effective global norms in favor of benign forms of conflict resolution. (See for example, The Path to Zero and At the Nuclear Precipice.) Whatever the details, this new world order would leave behind the fundamentally anarchic, self-help order of the world as it is now, and its ever-present potential for war.
Idealists identify the necessary ingredient for achieving this new world order as including enlightened leaders who believe that nuclear weapons offer no value—only danger. Therefore, the reasoning goes, they would work together globally and cooperatively to eliminate them. This demands political will, vision, faith, and leaders who can “embrace a politics of impossibility,” as the authors of The Path To Zero put it.
In the absence of such a transformation, however, realists see no plausible cooperative route to nuclear zero. As the bipartisan US Congressional Strategic Posture Commission reported in 2009: “The conditions that might make possible the global elimination of nuclear weapons are not present today and their creation would require a fundamental transformation of the world political order.”
That said, realists do not view sustaining nuclear deterrence as a superior alternative to a new world order that would, in fact, provide confident, enduring security for all. It is painfully obvious that in a new world order where all security concerns are resolved and none can emerge in the future, disarmament would be the preferred alternative. If such a world order were to emerge, movement toward nuclear disarmament would be the easiest decision—akin to giving up chemotherapy when the cancer is already in remission.
Envisioning such a new world order, however, does not make it a “practical alternative” to deterrence. Offering that vision as a solution to the fallibility of deterrence is neither brilliant nor clever. Doing so only pretends to solve the problem by imagining a future international system in which the underlying problems of mistrust and insecurity no longer drive state behavior as described by realists. The idealist solution is analogous to saying that the solution to homelessness is the widespread provision of housing. Realists respond, "We appreciate the vision, but have no confidence that you can get there."
In short, realists do not believe that a new world order enabling nuclear disarmament, as envisaged by idealists, is a plausible solution. As John Mearsheimer observes in The Tragedy of Great Power Politics: “Realists agree that creating a peaceful world would be desirable, but they see no easy way to escape the harsh world of security competition and war. Creating a peaceful world is surely an attractive idea, but it is not a practical one.” This point is not ideological or religious; it is based on a review of history, ancient and contemporary, and the unavoidable conclusion that “calculations about power dominate states’ thinking, and that states compete for power among themselves.” Evidence demonstrating the emergence of a more benign new world order is overwhelmed by evidence to the contrary, past and present: the Concert of Europe failed; the League of Nations failed miserably; the United Nations, as a reliable collective security institution, has failed; and all types of states violate established international norms when they perceive the necessity to do so. Thucydides would hardly be surprised by the basic nature of the contemporary world order.
Where to go from here? The question realists put to idealists is: What is more dangerous, the maintenance of nuclear deterrence or its absence in an international system that remains anarchic and conflict-prone—where mistrust abounds and the potential for civilization-destroying war is ever present?
Idealists solve the problem by envisaging an alternative new international system that does not exist, and shows no prospect for coming into being. Realists have no such luxury, which is why Thomas Schelling’s comment on the idealist’s solution is a devastating realist critique: “One might hope that major war could not happen in a world without nuclear weapons, but it always did. One can propose that another war on the scale of the 1940s is less to worry about than anything nuclear. But it might give pause to reflect that the world of 1939 was utterly free of nuclear weapons.”
Schelling describes a nuclear weapons-free world in the absence of a new cooperative order as a very dangerous place in which many countries “would have hair-trigger mobilization plans to rebuild nuclear weapons and mobilize or commandeer delivery systems, and would have prepared targets to preempt other nations’ nuclear facilities, all in a high-alert status … the urge to preempt would dominate; whoever gets the first few weapons will coerce or preempt. It would be a nervous world.” One might add that it would be a nervous world still armed with advanced conventional, chemical, and biological weapons—making a general war many times more horrific than was World War II.
The realist alternative is not to pursue nuclear disarmament in the vain hope that a new and benign world order somehow will emerge to enable cooperative global disarmament, especially if that pursuit is thought to increase the West’s vulnerability to war and coercion. Rather, the realist goal is to make deterrence as reliable and effective as possible—which is first a matter of good intelligence-gathering—while also preparing to the extent possible to limit escalation and destruction in the event deterrence fails. Realists certainly have differing recommendations on how to go about those tasks. But this general approach to the problem is no less plausible a solution than that offered by idealists, and in many prospective scenarios, it is far more plausible.
This discussion gets us to the central consideration of the usefulness of nuclear weapons. US nuclear weapons can provide a useful and sometimes unique deterrent effect in a self-help international system characterized by mistrust, conflicting interests, and the ever-present potential for crises and war. These US weapons also help to assure some allies concerned about their security situations who otherwise might consider independent nuclear capabilities. There is no doubt that the existence of nuclear weapons entails risks, but the comparison of those risks ought not to be with those of a relatively benign, cooperative world order that does not exist and shows no sign of emerging. Instead, those risks should be compared to the enduring international system described by Thucydides, but which is now armed with advanced conventional, nuclear, chemical, and biological weapons.
In this system that does exist, the value of nuclear deterrence may be deemed great—much as various medical treatments can simultaneously pose risks to the human body, but also be considered of great value in time of need. If human bodies worked reliably without that need, there would be no recourse to such treatments. If the international system was cooperative and reliably free from insecurity, conflict, and war, there would be no value in nuclear deterrence, and there would likely be no need for nuclear weapons. Until that is so, denying the value of nuclear deterrence is a pretense.
As Winston Churchill said: “Be careful above all things not to let go of the atomic weapons until you are sure, and more than sure, that other means of preserving peace are in your hands.” The emergence of a new, benign world order at this point is nowhere in sight, and the prospects for the cooperative move to nuclear zero appear to be zero. Realists do not pretend otherwise.
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