The Everyday Irrationality of Monothematic Delusion

Everyday irrationality is instructive for research into monothematic delusion in two respects. In the first three sections of the paper, we see that paranormal and other irrational beliefs result from strange experiences plus a normal range of cognitive styles not constitutive of clinical irrationality. No appeal is made to a clinically significant factor like a deficit resulting from brain damage or a distinctive form of bias. This throws into question the claim that delusion involves some more substantial form of irrationality than everyday irrationality. Second, monothematic delusions can display components of everyday motivated irrationalities like wishful thinking/weak self-deception and strong self-deception. However, these components constitute the ways in which more profound irrationality is involved and, often, the irrationality of monothematic delusion that occurs is less severe than these everyday cases of motivated irrationality. In general, there is no need to take delusion to involve a distinctive further irrationality that goes beyond the everyday and, indeed, many monothematic delusions involve less substantial irrationalities than many every day ones in either cold or hot forms.