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

How do terrorists persuade otherwise decent citizens to join their violent causes? Guided by early mass communication research investigating propaganda's efficacy and the model of intuitive morality and exemplars, we investigated the persuasive moral appeals employed by terrorist organizations known to be successful at recruiting others to their causes. We compiled a database of N = 873 propaganda items created by N = 73 violent terrorist organizations and content analyzed the moral appeals emphasized in each. Results revealed that terrorist groups' ideologies and motivations predicted the moral values they emphasized in their propaganda, and that ingroup loyalty and fairness appeals featured prominently across all propaganda. Terrorist groups' emphasis on purity in their propaganda was positively correlated with their attack frequency and with the number of human casualties they caused worldwide and in the USA. Terrorists' emphasis on ingroup loyalty in propaganda was also positively correlated with the number of US human casualties they caused. Theoretical and practical implications are discussed.