Delusional beliefs are false in most cases. And, probably, they are unjustified according any interesting accounts of epistemic justification. However, we believe that there are some positive things we can say about epistemic status of delusional beliefs. The aim of the paper (or, strictly speaking, the aim of the longer paper upon which the presented paper is based) is to defend two claims about the epistemic status of delusional beliefs. The claims correspond to two kinds of epistemic evaluations; consequentialist and deontological evaluations. First, delusions can have some good epistemic consequences that are at least indirectly related to the acquisition of true beliefs. Second, people with delusions are not epistemically blameworthy for their delusional beliefs.
Here are brief summaries of our argument for the claims.
(1) Typically, an epistemic agent achieves true beliefs by investigating in environment (e.g. beliefs from experience) and communicating with other people (e.g. beliefs from testimony). However, one might fail to use these canonical procedures productively when (1) he finds the world as too puzzling and inexplicable, (2) he finds himself as being epistemically incapable or (3) he is overwhelmed by negative emotions. On the basis of recent empirical findings and theories about delusions, we argue that delusions can have some good epistemic consequences by alleviating those factors that are harmful for the productive usage of the canonical procedures.
(2) The key notion in the deontological side of our project is the "ability to believe otherwise". We define it in terms of the responsiveness to evidence-related activities (such as observing facts, reading books, careful reasoning). Roughly, we argue that people with delusions are not blameworthy for the delusional beliefs because (1) someone is blameworthy for one's beliefs only if he could have believed otherwise, and (2) people with delusions couldn't have believed otherwise. For instance, a remarkable study by Freeman and colleagues reveals that people with delusions have difficulty in regarding alternative hypotheses as live options, which strongly supports premise (2).