Dehumanization increases instrumental violence, but not moral violence

Significance To eliminate violence, we must understand the motives that drive it. Most theories assume that violence is motivated by instrumental gain or impulsiveness, and is restrained by moral inhibitions. In these frameworks, dehumanization breaks down moral inhibitions by reducing perceptions of victims as fellow human beings worthy of concern. However, we argue that much violence is actually motivated by moral sentiments, and that morally motivated perpetrators wish to harm fellow human beings. Across five experiments, we show that dehumanizing victims increases instrumental, but not moral, violence. This distinction, between instrumental violence enabled by dehumanization, and moral violence directed toward human victims, has important implications for understanding how morality and dehumanization interact with violence, and for informing violence reduction efforts worldwide. Across five experiments, we show that dehumanization—the act of perceiving victims as not completely human—increases instrumental, but not moral, violence. In attitude surveys, ascribing reduced capacities for cognitive, experiential, and emotional states to victims predicted support for practices where victims are harmed to achieve instrumental goals, including sweatshop labor, animal experimentation, and drone strikes that result in civilian casualties, but not practices where harm is perceived as morally righteous, including capital punishment, killing in war, and drone strikes that kill terrorists. In vignette experiments, using dehumanizing compared with humanizing language increased participants’ willingness to harm strangers for money, but not participants’ willingness to harm strangers for their immoral behavior. Participants also spontaneously dehumanized strangers when they imagined harming them for money, but not when they imagined harming them for their immoral behavior. Finally, participants humanized strangers who were low in humanity if they imagined harming them for immoral behavior, but not money, suggesting that morally motivated perpetrators may humanize victims to justify violence against them. Our findings indicate that dehumanization enables violence that perpetrators see as unethical, but instrumentally beneficial. In contrast, dehumanization does not contribute to moral violence because morally motivated perpetrators wish to harm complete human beings who are capable of deserving blame, experiencing suffering, and understanding its meaning.