Ideally, we would have beliefs that satisfy norms of truth and rationality, as well as fostering the acquisition, retention and use of other relevant information. In reality, we have limited cognitive capacities and are subject to motivational biases on an everyday basis, and may also experience impairments in perception, memory, learning, and reasoning in the course of our lives. Such limitations and impairments give rise to distorted memory beliefs, confabulated explanations, elaborated delusional beliefs, motivated delusional beliefs, and optimistically biased beliefs. In the book, Bortolotti argues that some irrational beliefs qualify as epistemically innocent, where the notion of epistemic innocence captures the fact that in some contexts the adoption, maintenance or reporting of the beliefs delivers significant epistemic benefits that could not be easily attained otherwise. Epistemic innocence is a weaker notion than epistemic justification, as it does not imply that the epistemic benefits of the irrational belief outweigh its epistemic costs. However, it clarifies the relationship between the epistemic and psychological effects of irrational beliefs on agency. It is misleading to assume that epistemic rationality and psychological adaptiveness always go hand-in-hand, but also that there is a straight-forward trade off between them. Rather, epistemic irrationality can lead to psychological adaptiveness and psychological adaptiveness in turn can support the attainment of epistemic goals. Recognising the circumstances in which irrational beliefs enhance or restore epistemic performance informs our mutual interactions and enables us to take measures to reduce their irrationality without undermining the conditions for epistemic success.