AbstractConspiracy theories are widespread and have a profound impact on society. The present contribution proposes that conspiracy theories are explanatory narratives that necessarily contain justice judgments, as they include attributions of blame and accusations of unethical or criminal conduct. Conspiratorial narratives also are mental simulations, however, and may elicit genuine feelings of injustice also without evidence of actual malpractice. Indeed, conspiracy theories sometimes describe unfair events that are unlikely to have occurred, unethical authorities that might not actually exist, and so on. Here I propose two complementary processes that stimulate belief in evidence-free conspiracy theories: (1) Existential threats instigate biased mental processing and motivated reasoning, that jointly promote an alternative perception of reality; and (2) group allegiances shape how people perceive, interpret, and remember facts to highlight the immoral qualities of competing outgroups. Due to these processes, conspiracy theories elicit a set of distinct reactions such as poor health choices and rejection of science. Moreover, evidence-free conspiracy theories require interventions beyond traditional approaches to install justice principles, such as debunking falsehoods and reducing polarized intergroup distinctions. I conclude that the scientific study of conspiracy theories is part of, and has a unique place in, social justice research.