Why Do Differences Become Hostility? Group Identity, Threat Perception, and the Generative Mechanisms of Civilizational Division—From "Us-Them" Categorization to Hostility Spirals: An HHC Analytical Framework

Human societies have always contained differences of ethnicity, religion, language, culture, class, institutions, ways of life, and values, yet difference does not inevitably produce hostility. Distinct groups can coexist peacefully for long periods, cooperate, borrow from one another, and even undergo deep mutual integration. Under particular conditions, however, the same differences can be reinterpreted as threats, injustice, humiliation, or irreconcilable value conflicts, generating durable group hostility. The central problem for the study of civilizational conflict is therefore not why human beings differ, but through what mechanisms difference is transformed into hostility. Building on the preceding theories of dynamic coordination of happiness, relational embeddedness, compatibility between self-regarding and public-regarding good, and the Rational Public-Regarding Personality, this paper proposes the Difference-to-Hostility Transformation Model (DHTM). The model argues that group hostility is usually not a direct product of difference. It is generated through interacting mechanisms that may include social categorization, identity investment, resource competition or relative deprivation, threat perception, historical narratives and collective victimhood, moralization and sacralization of values, outgroup simplification and dehumanization, and conflict feedback. Social identity research shows that even minimal group distinctions can produce ingroup favoritism, but ingroup favoritism is not identical to outgroup hatred. Realistic conflict research further shows that competitive goal structures can intensify negative stereotypes and hostile behavior. Integrated threat research identifies realistic threats, symbolic threats, intergroup anxiety, and related perceptions as important correlates of negative outgroup attitudes. Research on identity fusion, sacred values, and competitive victimhood further suggests that when group identity becomes fused with personal selfhood, moral obligation, and historical trauma, compromise can increasingly be experienced as betrayal of the self and the group. The central claim is that hostility is generated through an interpretive and relational process: difference is categorized; categories become identity-laden; identities enter comparison; comparison generates perceived deprivation and threat; threat is amplified by historical and moral narratives; the outgroup is simplified and may be dehumanized; and conflict behavior then produces new experiences that appear to confirm the original fear. Hostility thus develops into a self-reinforcing spiral. The paper also argues that this process is not irreversible. Large-scale meta-analytic evidence on intergroup contact generally finds associations between contact and reduced prejudice across diverse settings, while the Common Ingroup Identity Model suggests that a broader sense of 'we' can reduce intergroup bias. Yet common identity also carries risks when it is used to demand that minority groups abandon prior identities. The more defensible HHC approach is therefore nested identity rather than compulsory homogenization. Paper 05 provides the group-level bridge for the Human Happiness Community: Great Unity does not require the prior elimination of difference. It requires weakening the automatic conversion of difference into threat and hostility, while strengthening alternative pathways through which difference can lead to understanding, cooperation, broader identity, and eventual civilizational integration.