Explaining delusional beliefs: A hybrid model

Introduction: In this paper we present and defend a hybrid theory
of the development of delusions that incorporates the central
ideas of two influential (yet sometimes bitterly opposing)
theoretical approaches to delusions—the two-factor theory and
the prediction error theory.
Method: After introducing the central ideas of the two-factor theory
and the prediction error theory, we describe the motivations for our
conciliatory project, explain the theoretical details of the hybrid
theory we propose, and answer potential objections to our proposal.
Results: According to the hybrid theory we advance, the first factor
of a delusion is physically grounded in an abnormal prediction error,
and the second factor is physically grounded in the overestimation
of the precision of the abnormal prediction error. Against
anticipated objections, we argue that the hybrid theory is
internally coherent, and that it constitutes a genuine hybrid
between the two-factor theory and the prediction error theory.
Conclusion: A rapprochement between the two-factor theory and
the prediction error theory is both possible and desirable. In
particular, our hybrid theory provides a parsimonious and unified
account of delusions, whether monothematic or polythematic,
across a wide variety of medical conditions.