Ideologies, worldviews, or simply personal theories, often acquire a distorted and pathological character, and become a factor of alienation rather than an epistemic resource and an aid for personal existence. This paper attempts to better define the limits and characteristics of this experience, which we call distorted intellectual beliefs, or general conceptual beliefs (GB), while trying to highlight both its sometimes dramatic background and its personal and social consequences, which are no less potentially deleterious. We believe that such experiences should (...) not be confused tout court with a broader and more complex phenomenon, such as extremism and politico-religious radicalism, but are a specific typology of that broader and multifaceted fact that is self-deception. We hypothesize that the self-deception implicit in experiences of intellectual distortion produces a cognitive dissonance of which the subject is normally, though with varying intensity, aware (or may become aware through honest introspection). The phenomenon occurs in two extreme forms: one is normal (sporadic), the other is exceptional (systematic). The passage from one to the other is a complex process of escalation and de-escalation, on which multiple external and internal variables act. In its ascending path, it essentially coincides with a process of psychological polarization and cognitive "de-pluralization", while its descending phase marks a return to reality and a "re-pluralization", where the subject returns to being what he basically is, namely, an active and tireless meaning seeker. In the central part of the chapter, similarities and differences between processes of deradicalization and phenomena of religious deconversion are analyzed, with reference, among others, to the case of the Austro-Hungarian writer Arthur Koestler. -/- An abridged version of this text has been delivered for the Workshop "Explaining Extreme Belief and Extreme Behavior", September 15-16, 2022, Vrije Universiteit Amsterdam. I am grateful to David Konstan (NYU) for reading and commenting on a first version of this chapter and to Rik Peels (VUA) for his comments and questions during the Workshop. I would also like to thank my bachelor's and master's students at UDG, who discussed these topics at length with during semester 2022-B. (shrink)