I might actually expect the opposite. Mental illness is conventionally defined in terms of a marked impairment of everyday cognition compared to the general population, i.e. instrumental irrationality. Yet relatively few mental disorders, from my reading, seem to have direct effects on an epistemic level.
Yet relatively few mental disorders, from my reading, seem to have direct effects on an epistemic level.
That sounds very strange to me. The standard things like schizophrenia, paranoia, etc. are characterized precisely by a "wrong" picture of reality. If a paranoiac is unwilling to venture out to buy groceries, that's not a failure of instrumental rationality -- if there actually were people outside his door who want to kill him (as he believes), his behavior would be perfectly rational.
Even depression has a strong epistemic component.
Another month has passed and here is a new rationality quotes thread. The usual rules are: