Why we fight: investigating the moral appeals in terrorist propaganda, their predictors, and their association with attack severity.

This article investigates the moral appeals used in propaganda by violent terrorist organizations to persuade otherwise nonviolent individuals to join their causes. Analyzing 873 propaganda items from 73 terrorist groups active in the United States, the study applies the model of intuitive morality and exemplars (MIME) alongside moral foundations theory (MFT) to identify which moral values—care, fairness, ingroup loyalty, authority, and purity—are emphasized. Findings reveal that terrorist groups’ ideologies and moral motivations predict their propaganda’s moral focus, with extremist right-wing and religious groups emphasizing binding values (especially loyalty and purity), while left-wing and single-issue groups emphasize individualizing values (notably fairness and care). Moreover, the study finds that propaganda emphasizing purity correlates positively with higher attack frequency and casualties worldwide and in the USA, and loyalty appeals correlate with increased U.S. casualties. These results support viewing terrorist groups as distinct morality subcultures whose closed media systems reinforce specific moral values, offering theoretical insights and potential avenues for developing targeted counter-messaging strategies.