Just world belief mitigates depression throughout public health adversity: the immediate and longitudinal mediation of hope

Belief in a just world (BJW) buffers against negative emotions. According to Lerner’s Just World Theory and Snyder’s hope theory, the buffering effect could be mediated by hope, but empirical evidence is lacking, and the detailed mechanism remains largely unknown. Drawing on the multidimensionality of BJW and hope, the current research proposed a functional specificity model regarding the specific roles of their dual components—namely, agency thinking and pathways thinking (of hope), as well as personal belief in a just world (PBJW) and general belief in a just world (GBJW) in mitigating depression-related symptoms. The model was tested by a cross-sectional design (Study 1, n = 1151) during the COVID-19 lockdown period, as well as a two-wave longitudinal design (Study 2, n = 291) which spanned from 1 month prior to the lifting of the lockdown (Time 1: T1) to 4 months after the lockdown was lifted (Time 2: T2) in China. In Study 1, agency thinking—but not pathways thinking—was found as the primary mediator linking BJW to depression-related symptoms. Notably, PBJW showed a consistent indirect effect via agency thinking (the PAD route), whereas the corresponding effect of GBJW (the GAD route) was weak and unstable. In Study 2, the PAD route remained statistically significant despite the absence of robust lagged effects of agency thinking on depression. The findings provide preliminary evidence that pathways thinking and agency thinking play distinct mediating roles in the influence of GBJW and PBJW on depression-related symptoms. They suggest the necessity of distinguishing between belief systems and motivational processes when examining psychological resilience, particularly in the context of public health crises.