The rationality of belief change and the unexpected effects of a conflict of values

International audienceThis paper is based on a question that is already present in the work of Festinger et al (1956): why is the unequivocal disproof of a given belief an insufficient reason for abandoning that belief? We will first outline the cognitive dissonance theory (Festinger, 1957) and then discuss how, in a seemingly counterintuitive way, beliefs that are contradicted by facts—that is, factual contradictions— lead only to minimal belief changes, whereas beliefs that are in contradiction with some fundamental value held by an individual—that is, axiological contradictions—represent a challenge to the individual's entire belief system and may lead to disaffiliation. The objective of this paper is to propose an alternative explanatory hypothesis to that of Festinger—which is now disputed—and thus provide new answers to help understand the process by which beliefs are abandoned. This paper has epistemological ambitions insofar as it aims to demonstrate that by means of a paradigm based on reasons (Boudon, 1992) and abduction (Peirce, 1931)—the Boudon-Peirce Paradigm—it is possible to propose an alternative, explanatory hypothesis to that of Festinger's, and to provide new answers to facilitate understanding the process of abandonment of beliefs. This comprehensive paradigm has allowed the discovery that conflicts of values—axiological contradictions—can cause disaffiliation