Five studies across cultures involving 661 American Democrats and Republicans, 995 Israelis, and 1,266 Palestinians provide previously unidentified evidence of a fundamental bias, what we term the "motive attribution asymmetry," driving seemingly intractable human conflict. These studies show that in political and ethnoreligious intergroup conflict, adversaries tend to attribute their own group's aggression to ingroup love more than outgroup hate and to attribute their outgroup's aggression to outgroup hate more than ingroup love. Study 1 demonstrates that American Democrats and Republicans attribute their own party's involvement in conflict to ingroup love more than outgroup hate but attribute the opposing party's involvement to outgroup hate more than ingroup love. Studies 2 and 3 demonstrate this biased attributional pattern for Israelis and Palestinians evaluating their own group and the opposing group's involvement in the current regional conflict. Study 4 demonstrates in an Israeli population that this bias increases beliefs and intentions associated with conflict intractability toward Palestinians. Finally, study 5 demonstrates, in the context of American political conflict, that offering Democrats and Republicans financial incentives for accuracy in evaluating the opposing party can mitigate this bias and its consequences. Although people find it difficult to explain their adversaries' actions in terms of love and affiliation, we suggest that recognizing this attributional bias and how to reduce it can contribute to reducing human conflict on a global scale.any human conflicts appear extraordinarily difficult to resolve even when outsiders can see the contours of a rational resolution. Ideological opponents risk the health of their economies and their planet because they are unable to make political compromises. Ethnic and religious groups across the world engage in mass acts of violence, rejecting solutions of mutual benefit that involve sharing power, land, or religious sites. Why are so many conflicts so intractable when people on both sides could gain from a compromise?Approaches to this question typically center on the complexity and profundity of the issues involved and each side's construal of the conflict (1, 2). An additional, deeper barrier to conflict resolution may be simple pessimism toward compromise. If adversaries believe inflexibility on the other side renders mutual compromise impossible, they will be unlikely to adopt seemingly rational strategies for conciliation (3). In other words, the perception of conflict intractability may be an independent cause of a stalemate. Here, we identify a fundamental cognitive bias that contributes to the belief in conflict intractability, and may therefore contribute to conflict spirals (4-6).We predict and observe that people often attribute their outgroup's actions during conflict to hatred. This attribution occurs despite evidence that intergroup aggression stems at least as much, if not more, from ingroup love (7-13). We hypothesized that whereas ...