Kettles of Hawks: Public Opinion on the Nuclear Taboo and Noncombatant Immunity in the United States, United Kingdom, France, and Israel

Security Studies · 2022 · 73 citations

• Political Science
• Political Science
• Sociology

Recent scholarship has established that a majority of Americans will support the use of nuclear weapons and violate the principle of noncombatant immunity when American lives are on the line. Some scholars contend, however, that these hawkish American attitudes are an outlier and that other Western democratic publics have more fully internalized the nuclear taboo, as well as the prohibition on deliberately killing civilians. To investigate cross-national attitudes on these important norms, we conducted a survey experiment of American, British, French, and Israeli citizens. We find that American attitudes are not exceptional. Rather, Israeli respondents display the most hawkish preferences; French and American citizens are roughly equally hawkish; and the British public is consistently the least supportive of nuclear use or targeting civilians. Categorical prohibitions—against nuclear use and targeting civilians—do little to shape public opinion in these four countries. Instead, public opinion in each state follows the same consequentialist logic: a majority or near majority of respondents are willing to support using nuclear weapons when they are more effective than conventional options, but support declines when collateral civilian deaths rise. Respondents’ preferences for compatriots over foreign civilians and respondents’ retributiveness help explain individual-level variation in attitudes.

The Rule of Law and the Role of Strategy in U.S. Nuclear Doctrine

International Security · 2021 · 36 citations

• Political Science
• Political Science
• Law

Abstract In 2013, the U.S. government announced that its nuclear war plans would be “consistent with the fundamental principles of the Law of Armed Conflict” and would “apply the principles of distinction and proportionality and seek to minimize collateral damage to civilian populations and civilian objects.” If properly applied, these legal principles can have a profound impact on U.S. nuclear doctrine. The prohibition against targeting civilians means that “countervalue” targeting and “minimum deterrence” strategies are illegal. The principle of distinction and the impermissibility of reprisal against civilians make it illegal for the United States, contrary to what is implied in the 2018 Nuclear Posture Review, to intentionally target civilians even in reprisal for a strike against U.S. or allied civilians. The principle of proportionality permits some, but not all, potential U.S. counterforce nuclear attacks against military targets. The precautionary principle means that the United States must use conventional weapons or the lowest-yield nuclear weapons that would be effective against legitimate military targets. The law of armed conflict also restricts targeting of an enemy's leadership to officials in the military chain of command or directly participating in hostilities, meaning that broad targeting to destroy an enemy's entire political leadership is unlawful.

Does the Noncombatant Immunity Norm Have Stopping Power? A Debate

International Security · 2020 · 13 citations

• Political Science
• Political Science
• Political economy

Our 2015 survey experiment—reported in the 2017 International Security article “Revisiting Hiroshima in Iran”—asked a representative sample of Americans to choose between continuing a ground invasion of Iran that would kill an estimated 20,000 U.S. soldiers or launching a nuclear attack on an Iranian city that would kill an estimated 100,000 civilians.1 Fifty-six percent of the respondents preferred the nuclear strike. When a different set of subjects instead read that the air strike would use conventional weapons, but still kill 100,000 Iranians, 67 percent preferred it over the ground invasion. These findings led us to conclude that “when provoked, and in conditions where saving U.S. soldiers is at stake, the majority of Americans do not consider the first use of nuclear weapons a taboo and their commitment to noncombatant immunity is shallow.”2By 2015, we had been researching American public opinion on the use of nuclear weapons and the ethics of war for several years. Many of our previous findings about the U.S. public's hawkish attitudes had been unsettling. Nevertheless, the levels of public support we found in this study for a strike that so clearly violated ethical and legal principles on the use of force were deeply troubling.We proposed, therefore, that future research on the nuclear taboo and the noncombatant immunity norm focus on interventions that might blunt these disturbing instincts of the American public. We are gratified that Charli Carpenter and Alexander Montgomery have taken up that challenge and are contributing to the emerging debate on this important subject.3 A number of the ideas they advance are important: scholars should study the sources and kinds of information and arguments that citizens would likely receive in real conflicts; the influence of historical analogies; and the differences and similarities among civilian elite attitudes, military views, and public opinion.4Nevertheless, we find Carpenter and Montgomery's main critiques unconvincing. We remain deeply skeptical about how much stopping power legal and ethical norms are likely to exert on the U.S. public if it is ever faced with the kind of terrible dilemmas that can emerge in the crucible of war. We believe that the unsettling findings of our experiments make the effort to understand public opinion, and to discover how to influence it, particularly urgent. Our common goal is to create experiments that illuminate how the public would react in real-world crises, maximizing what is called the “external validity” of experiments. In this response, we propose some novel ways to realize that common objective.We applaud Carpenter and Montgomery's efforts to replicate our findings and assess the degree to which legal and ethical norms affect public opinion. We wish we could replicate their findings in turn to examine related questions, confirm the accuracy of measures, and assess alternative interpretations. Unfortunately, we are unable to do so. For despite agreeing to this debate, and despite us sharing our data with them, Carpenter and Montgomery declined to share their replication data or even their online appendix with us before publication.Nevertheless, a careful reading of their article reveals important reasons to be skeptical of their central conclusions. Carpenter and Montgomery's main claim is that the scenarios we used were “psychologically stacked in favor of atrocity” because we chose “not to mention international law or norms.” They argue that omitting references to law or norms constitutes “priming by omission.”To test this argument, they begin by replicating the conventional attack condition from our 2015 experiment. They report that 57 percent of subjects indicated that they preferred the air strike, 10 percent less than we found. As they acknowledge in footnote 55, however, this difference is not statistically significant. Therefore, they clearly state that “we do not dispute Sagan and Valentino's overall finding.”Carpenter and Montgomery then ran several experiments using an altered version of our original conventional weapons scenario that substituted the words “Iranian Civilians” for “Iranian City” in the headline (a change that might have led some subjects to believe that the United States would target all civilians in Iran).5 In these experiments, subsets of subjects were asked to consider international law and ethical norms before indicating their preference for the air strike or ground war in the Iran scenario, and in others after they indicated their preference. Surprisingly, Carpenter and Montgomery do not report the results of the two direct experiments comparing the pairs of conditions in which subjects were primed or not primed on legal knowledge and ethical sensitivity. They do not report the results from the two groups that received the law question before and after the air strike question at all. They do report a decline in preferences for the strike (from 54 percent to 46 percent) when subjects received the ethics prime before the Iran question, but this decline refers to a comparison between one group that received the ethics prime before the air strike question, and subjects pooled from two different subgroups that did not, although the different treatments these pooled groups received is unclear (Carpenter and Montgomery never explicitly describe each of their nine different treatment groups). In footnote 63, nonetheless, Carpenter and Montgomery acknowledge that even this change is not statistically significant at the conventional p < .05 level.One of the core tenets of experimental research is that researchers manipulate only one variable between any two comparison conditions. Carpenter and Montgomery repeatedly violate that rule in reporting their results. For the sake of transparency, in their reply, Carpenter and Montgomery should report the means and standard errors of their key experimental conditions (at least groups 1, 2, 6, and 7) separately and the results of the direct comparisons between their primed and unprimed conditions for law and ethics.Even if some of Carpenter and Montgomery's results are statistically significant, the effect is substantively small. Unlike Carpenter and Montgomery, we do not find it reassuring that 46 percent of respondents preferred the strike even after being primed to consider the ethics of targeting civilians. Nor are we reassured to read that 39 percent of respondents who “strongly agreed” that killing civilians was wrong nevertheless preferred the strike that would kill 100,000 of them. We were even less comforted after reading in footnote 62 that an additional “80 percent of those who only somewhat agreed with the ethical norm supported the strike.” For the sake of transparency, in their reply, Carpenter and Montgomery should report the total percentages of respondents who supported the strike and clarify which groups received the questions about law and ethics, and in what order, before or after answering the question about Iran.Carpenter and Montgomery do report that subjects who agree that it is never legally permissible to target civilians are less likely to prefer the air strike. They acknowledge, however, that 45 percent of subjects who agreed that targeting “the civilian population” violates international law nevertheless supported doing just that. Indeed, if we include the percentages of subjects who answered the law question incorrectly and preferred the strike, it appears that a majority or near majority of all subjects primed on international law actually preferred the strike. We do not understand how these results make Carpenter and Montgomery “far less pessimistic” about the public's apparent willingness to violate the noncombatant immunity principle.6The relatively small effect of priming subjects on considerations of law is mirrored in studies of torture and drone strikes that Carpenter and Montgomery cite for support. Geoffrey Wallace, for example, finds that telling subjects that torture violates both U.S. and international law reduced support by 6 percent, a drop he describes as “a systematic but substantively modest effect.”7 Sarah Kreps and Wallace report that priming subjects that certain U.S. drone strikes were illegal decreased support by between 6 percent and 8 percent. They acknowledge, however, that “over 40% of the public approves of the strikes even when told they would violate international law, almost twice as many subjects as opposed the strikes,” and that legal priming “does not make the public more willing to put their own troops in harm's way.”8According to Carpenter and Montgomery, our article understated the true force of ethics and law because a “framing effect was created through the either/or structure of the Iran scenario question.” They call this effect “the tyranny of closed-ended questions.” In one “Revisiting Hiroshima” experiment, however, we provided respondents with a third option—a diplomatic settlement in which Ayatollah Ruhollah Khamenei was permitted to remain as a spiritual leader under a democratic government. Forty-one percent of our subjects chose that option, but 40 percent still preferred to launch a nuclear strike.The basic closed-ended design that we have used in many experiments is routinely employed in public opinion experiments, however, including many of those cited favorably by Carpenter and Montgomery. It also forms the foundation of the famous “trolley car” experiments, designed by moral philosophers to assess moral intuitions about killing.9 Closed-ended questions are particularly helpful for testing the strength of competing norms because they force respondents to confront difficult dilemmas. Carpenter and Montgomery, however, argue that this kind of question produced “moral confusion” and exaggerated “public antipathy” to noncombatant immunity.We do not think that subjects who expressed a desire for a third option in their open responses are suffering from “moral confusion.” Instead, they are (understandably) seeking to avoid the moral dilemma that they confront. Carpenter and Montgomery claim that “because norm conflicts can reduce support for prohibition norms in warfare, pitting the protection of Iranian civilians against the protection of U.S. troops could have biased Sagan and Valentino's experiment in favor of striking the city.” Yet, that is exactly what researchers testing for the stopping power of norms should do: “stress test” norms to determine how much they constrain behavior when other values are at stake.Carpenter and Montgomery repeatedly claim that our Iran scenario is a “tough test” for the power of norms. Nevertheless, it is a realistic and relevant test, for it is exactly in such scenarios that the United States might be tempted to violate the principle of noncombatant immunity. As history has shown, and as our experiments have repeatedly found, it is easier for people to voice support for an abstract normative principle (such as whether they believe killing civilians is always wrong or illegal) than it is to uphold that principle when it conflicts with other core values. Violating such principles may produce distress and a sense of tragedy, but for many Americans, these emotions do not possess “stopping power” when U.S. soldiers' lives are perceived to be at risk.We disagree with Carpenter and Montgomery that studies that do not prime subjects on ethics or law are guilty of “priming by omission,” or that this concept constitutes a useful critique of any survey experiment. Although we did not prime subjects to consider ethics or law, neither did we prime them to consider the potential environmental effects of a strike; provide graphic images of the Iranian victims; or discuss the potential that a nuclear or conventional attack would create a horrible precedent, increasing the likelihood of similar attacks against the United States. It that these considerations would support for of noncombatant immunity as much as or more than priming on law or and Montgomery claim that our scenario subjects to target civilians the is not Our did not report that Iran had supported or did not read that were military in the or that the civilians might be contributing to the war effort by to Iranian These considerations would likely support for of noncombatant immunity. are not Carpenter and Montgomery also guilty of “priming by all survey experiments, considerations that might have public opinion one or only that “priming by could be to our results would be if it could be that the of all considerations that citizens would in the real to the air strike. Carpenter and Montgomery have of how these competing considerations would therefore, to claim that our experiment was any less than their believe that Carpenter and Montgomery are to argue that legal and moral considerations would be in real-world public in military We also believe that such would produce competing about the and of different military examine this in we a survey experiment, by to a representative sample of subjects were to one of experimental conditions. condition the main of the 2015 “Revisiting Hiroshima” nuclear In a the was to that the of had that the nuclear attack would violate international of that the U.S. has which have war attacks on In the third the that the about whether the attack violate international of that the U.S. has of the that which have war attacks on civilians. of the however, the strike would be legal is a Iranian military the city and the strike could be against that We believe that this is and and that such an attack would be Nevertheless, it because this kind of has been in the to attacks on the of Hiroshima and and the and results are in As in “Revisiting subjects were asked whether they preferred the nuclear air strike or of the ground war. They were then asked whether they the strike violate the international of Fifty-six percent of subjects the strike would be and percent of subjects preferred the air strike in the percent of subjects who read that the that the strike would be illegal but 40 percent of respondents who read that nevertheless preferred the strike. 8 percent drop in support was not statistically significant When subjects read that the about whether the strike was however, that the strike would be illegal to percent, and preferences for the attack to percent, although the change in preferences also was not statistically significant experiment also the of Although neither our experiments Carpenter and Montgomery's or by the that the of the decline in support from 2015 and was a decreased willingness of in to support a strike they was by In our original 2015 percent of and percent of they preferred the strike by on In however, only percent of supported the strike, percent of still in the survey were percent more likely to support the strike, even when for other such as and would the many that the public would in the real-world Carpenter and Montgomery are that some respondents the to when their but this only the of our experiment, for such would likely in real-world about military It is that the who as in the from to both for an illegal war against and that and to the by the the of the under law in is still and some legal scholars argue that even if a war might still be as the the When with about law and ethics, the U.S. public not always with who an is if those are the of the stopping power of norms is public to the in that the United States had been a as after the the a think the use of torture against in to important information can be percent that torture was never In Americans were to including that was illegal and and that U.S. did not to torture or were even if they As found that support for torture actually after in 2015 when the the used that many consider to be torture on people of these or not percent that they were only percent that they were in 2015, the could still be or the repeatedly that the United States much than In a in we asked a sample of Americans whether they agreed or with the that “the United States should use much than to information from percent for Americans, moral and legal arguments against did not have “stopping strikes such as those in our experiments should never be They would be and the principles of and in the to the and by the United States as They would not and could even increasing among and a for future by Our research however, that it would be to that the majority of Americans, or even all American agree with that and Montgomery claim that they find of the kind of instincts we among some subjects in “Revisiting they have not their we on their of We however, against using as the of these In our 2015 experiment and our support for the for was among the of preferences for the strike against Iran that support for war and that for they support using force this of or it people the of they actually favor for just war and the law of not to the public's ethical which are all not We just war and the law of to constrain common We these to the of is important for scholars to their open to common and not to Carpenter and Montgomery that deeply about the civilian immunity norm and the Americans, however, do not have a what these and find that percent of Americans report that they these but not what they percent a about what they only percent a about what they and percent never of such a previous Carpenter and Montgomery that any key from both the study and that we more on the We agree with that We just disagree about how this Sagan and for their to our We their sharing their 2015 data with us after of their which we are in a to of We them and other scholars to the online data and researchers to to this by studies that include direct of the power of we were to that Sagan and do just that in their Although they deeply skeptical about how much stopping power legal and ethical norms are likely to exert on the U.S. we found it that the they in their Iran a change in the of that the is still stacked against these much so that we might have the we of debate between Sagan and and We then discuss their findings and some of our additional research this debate is about how scholars think about the study of norms in international We do not to Sagan and Valentino's findings so much as to to and the important research they have We agree with Sagan and on the of research in this We also agree that attacks on civilians are and and should never be We however, in key we on an about the of in that norms have Sagan and Valentino's original findings support for air strikes against civilian led them to conclude that to noncombatant immunity is we argue that the of ethical norms against nuclear use and civilian one would support for the Indeed, we find that only 54 percent of Americans would even such an and priming with a question ethical norms support to 46 percent, which is a majority and a Sagan and Valentino's results that less than percent of Americans would support such an with a similar of about 8 percent when to information international we disagree on how and how much to on to moral For example, Sagan and that the drop we from 54 to 46 percent support for is not statistically one the for at the of p < As we in our we find a drop of percent p < for the effect of the question and the from to In it sense to and at results if they do not this and them if they we that in our only percent of Americans to the study of questions may be an for survey not only because citizens and are with only two but also because they can their own and moral of might the likelihood that international norms would the of because it is not the public that whether the of war be we disagree with Sagan and on in survey and We agree with them that our study is more or less than that both studies were on a representative this is a should also to be experimental be representative of real-world conditions under which a would be We think that Sagan and Valentino's on the survey to the of these in what can be from survey experiments about the power of were after we our findings at the for International Security and at in Sagan and their own in which the of civilians is at least called question by the of a in our of any on international law Yet, we think that Sagan and Valentino's also and our Sagan and find an 8 percent drop in support for the strike in the condition where the acknowledge it would be a mention of international law in any “stopping power” that legal considerations can have an even in scenarios where one might the Indeed, this a the other forms of we remain the in Sagan and Valentino's experiment, including the of the of relevant and even when the agree that the strike would be they are still it as an to respondents that military believe that international law may be or when than moral a key of the original as citizens from the only voice the is the a war on the this is less an of the norm than of the and to We would any drop in support to be small in such a if not to opinion in the other the of the We were both that strike support and that it as much as 8 the of the in Sagan and Valentino's with to In a real-world scenario, we would such as the United and and to the that it is illegal to target citizens under the Indeed, the might much more in the than the as we have it is that the would make such an and even less likely that they would make an illegal even the of the and even with the of about moral Sagan and Valentino's still an that would the war. As we describe in our the of this experiment is on respondents as the claim that of civilians can It is to that the U.S. military It would still be even if the from the also information that the of the was by the structure of Sagan and Valentino's experiment a for these effects and those that we discuss in our which all the of about real-world public opinion that could be from this We would be to a more version of the experiment where the did not from the at but from the or a where about and were expressed by at least some than the and where it is that the the are than and to the by the of public opinion on that public opinion has not always been by moral We think the they also actually our about the of and in survey questions about to norms. They cite results from a survey question that think the use of torture against in to important information can be their which we argue respondents about the of the torture survey question they cite the claim that is at In each citizens are asked by a or to believe these as a for in It is that they would do forms of can have effects as Charli Carpenter and that and of in of this in can be if those are to A article by Alexander Montgomery, and finds for these respondents to war respondents more likely to believe that international law such in certain those who of studies support for war are to also favor such war such as these are not only of public they are where public of international norms are Although study is we think the use of and the of their results in the are of what the apparent of American public to norms such as the torture are deeply that the could through of civilian the nuclear or other questions, on how they are such as Sagan and and goal is to determine how norms can be than to think about these of this is to that experimental are not one of many useful ways to important questions at the of and moral We this is only the of a on how to this Sagan and and for on of their