In this chapter, we consider a cultural evolutionary psychological framework for understanding the origin, maintenance and diffusion of beliefs, and illustrate the utility of such a framework with two case studies – religious belief systems and conspiracy theory beliefs. A cultural evolutionary psychology of belief considers four broad sets of interacting factors: the content of a belief, a belief’s fit with individual conditions, the social dynamics surrounding a belief, and the socioecological conditions that promote or suppress a belief. A cultural evolutionary psychology of belief overcomes the limitations to what we call standard evolutionary psychology, a school of thought that emphasizes the activation of innate cognitive modules for understanding the generation and spread of beliefs. With this chapter, then, we aim to show how social and cognitive science researchers can approach the study of beliefs from an evolutionary perspective without committing to the controversial assumptions of standard evolutionary psychology.

Conspiracy theories (CTs) and CT belief stem from uncertain, hard to explain, crisis situations, especially when strongly held social and political identities are threatened making people feel anxious, insecure, or out of control. Connected to alarming developments in world politics, CTs are no longer manifestations of extremists and paranoids. As salience increases, scholars continue to examine their antecedents and consequences. This chapter highlights the interdisciplinary roots of the study of CTs and CT belief. It sets the stage with important definitions and measurement challenges, then reviews scholarship on psychological, social, political, and situational factors behind CTs and CT belief. Consequences are vast, allowing for only brief discussion of the spread, persistence, and prevalence related to negative health, social, political, and environmental effects. As it is unlikely that broad weaponisation of CTs or their blaze online will cease in the near future, the chapter concludes by discussing directions for future research.