*Originally published in 2022. Get E-International Relations delivered to your inbox, free of charge. As you sign up, consider becoming a paid subscriber, or make a donation, to support our work.

U.S. President Joe Biden’s May 2022 essay in The New York Times refocuses attention on the debate over the risk of escalation to wider conflict, including nuclear war, in the current conflict in Ukraine. What useful tools do social scientists have to help understand these risks? Some experts writing in major policy magazines, newspapers, and online fora have made reference to the “stability-instability paradox.” Is this widely known element of nuclear deterrence theory relevant to the current war in Ukraine? Our answer is “no, it is potentially misleading.” The concept, introduced by Glenn Snyder in 1965, has for some become a standard assumption of nuclear deterrence theory. It proposes that rivals who each possess a nuclear deterrent may experience greater low-level conflict because the stability of nuclear deterrence will embolden one side to engage in lower-level conventional military action, confident the other side will refrain from responding decisively in order to avoid escalation to nuclear war. 

In this article, we argue that the theory should not be given much weight by U.S. and NATO policy makers, because it lacks factual support. Rather, we suggest how discarding the paradox can lead to different insights and policy guidance based on well-supported concepts from conflict and deterrence studies.

At first glance, the stability-instability paradox seems a good description of the current Russia-Ukraine war. Indeed, Andrew Kydd makes the case that “the stability-instability paradox actually gives hope that escalation may be avoided, rather than additional reasons for fear.” If Russia, the weaker conventional power, has been emboldened to invade Ukraine, this is likely due to confidence in a restrained U.S. response, consistent with the paradox’s prediction that nuclear states will not escalate beyond “low-level” conventional conflict, such as a proxy-war.

However, Emma Ashford and Joshua Shifrinson also employ the paradox to make a different argument. They claim that, under “the stability-instability paradox, in which states, stalemated in the nuclear realm, might be more willing to escalate in conventional terms,” there is a greater chance of “escalation to a broader [conventional] war.” Among “multiple paths” to potential wider conflict they point to the increased presence and proximity of NATO and Russian troops (including in Belarus) which make “accidental confrontation between the sides more likely,” and the possibility of a Russian attack on Western weapons supply lines. Kydd disagrees, arguing that “while the paradox frees up Russia to invade Ukraine, it also frees the West to respond with aid to Ukraine, so long as that does not cross the threshold to direct engagement with Russian forces” (moving the conflict from low- to medium-level).

Before rushing to apply the paradox for policy prescriptions in this exceptionally dangerous environment, let’s consider three fundamental questions. First, how much stock should be placed in the stability-instability paradox? Second, do we need the paradox to explain the behavior of Russia and the United States in this crisis? Third, what might be the benefits of ignoring the paradox?

Where’s the evidence?

To address the first, we acknowledge the paradox’s long and distinguished theoretical pedigree, including Snyder and other major scholars such as Charles Glaser........

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