Abstract

One idea that has been extremely influential within cognitive neuropsychology and neuropsychiatry is that delusions arise as intelligible responses to highly irregular experiences. More precisely, over a number of years Brendan Maher developed a proposal which maintained that an individual adopts a delusional belief because it serves to explain a ‘strange’ or ‘significant’ experience (see Maher 1974, 1988, 1999). Maher’s approach to understanding delusions is often called ‘explanationism’ (Bayne and Pacherie 2004).

Even though explanationist accounts have been fairly popular in cognitive neuropsychiatry, the framework has been questioned by a number of philosophers on the grounds that delusions are quite obviously very bad explanations. Indeed, since delusions strike most of us as highly implausible, it is hard to see how they could explain any experience, no matter how unusual.

This talk will have two aims. First, I shall distinguish three distinct ways in which a delusion might be thought to be explanatorily inadequate, each of which poses a distinct challenge for the explanationist approach. I shall then defend the approach from these challenges by sketching how it can plausibly explain two delusions involving misidentification, the Capgras delusion and thought insertion.

As we will see in the discussion of these delusions, the sort of explanationist account I propose posits at least two discrete ways in which delusional cognition departs from ordinary cognition, one of which involves the cognitive mechanisms underlying hypothesis generation.