Why have nuclear weapons not been used after they seemingly effectively led to the capitulation of Japan in World War II? One important explanation advanced by Nina Tannenwald and others is that first usage has become stigmatized as unacceptable. Indeed, the argument goes, the normative prohibition against first use has become so strong that it is like a “taboo.”
A key characteristic of a taboo is that beliefs about wrongness cannot be easily manipulated by shifting peoples’ perceptions of costs and benefits of violating the normative prohibition. A new paper (pdf, non-gated) by Scott Sagan, Daryl Press, and Benjamin Valentino shows that the moral aversion to using nuclear weapons is much weaker than the taboo argument suggests, at least among the American public. The authors asked survey respondents whether they approved of or even preferred the use of nuclear or conventional weapons in two scenarios: the discovery of an Al Qaeda nuclear lab in Syria and retaliation against an Al Qaeda attack on a cruise ship that had led to mass American fatalities. The retaliation was targeted at a base in Syria. Both attacks would lead to Syrian civilian casualties. (Syria was chosen because at the time of the survey, Americans were largely indifferent about the country).
Randomly selected groups of survey respondents were told that the nuclear and conventional attacks would either be equally effective or that the nuclear attack had a greater chance of success. Everything else was held constant. When both options are equally effective, only a relatively small proportion of respondents prefers nuclear weapons, presumably to “send a message.” Yet, when nuclear weapons are portrayed as having a 90% success rate while conventional weapons hit the target with only 70% of the time, a (small) majority of Americans prefers nuclear weapons to conventional ones. This effect is even greater when the discrepancy in success rates widens further. Moreover, among the people that still prefer conventional weapons, most say that they do so not out of moral aversion but because they are concerned that first usage sets a dangerous precedent.
Obviously, these are results of one survey among the general public. They may not accurately convey how elites or other publics think. Especially the President has a unique set of considerations on this question. What the results do convey, however, is that a President may very well be able to muster majority support for nuclear usage by appealing to the effectiveness of the latest generation of nuclear weapons. Perhaps we ought not to be surprised by this but it is sobering and important to realize nonetheless.