Revisiting the Irrationality of Delusions: a reply to Vaughan Bell

Today I want to share some thoughts on last week's interesting post on de-rationalising delusions.

In the pre-print of their thought provoking paper, Vaughan Bell has argued, with Nichola Raihani and Sam Wilkinson, for the view that models of delusions need to include "alterations to coalitional cognition" and to depart from the dominant views that characterise delusions primarily as irrational beliefs.

Here I am not going to discuss their positive proposal, which sounds plausible, but just comment on how the so-called 'dominant account' the authors object to in the paper groups together heterogeneous views of what makes delusions distinctive and pathological.

Some of the cognitive accounts Bell and colleagues have as their polemical target hold that: (1) the irrationality of delusions is distinctive from (more radical than) the irrationality of other beliefs; and (2) the irrationality of delusions is the main source (if not the only source) of their pathological nature. Although my view of delusions is cited as an example of the dominant cognitive account Bell and colleagues criticise, I reject both (1) and (2), for reasons that align with Bell and colleagues' focus on coalitional cognition.

Is the irrationality of delusions distinctive?

As argued in Delusions and Other Irrational Beliefs and more recently in Delusions in Context, my view is that the irrationality of delusions is not different in kind from the irrationality of many beliefs that we would characterise as neither delusional nor pathological, such as self-enhancing beliefs, prejudiced beliefs, and superstitious beliefs. 

Standard definitions of delusions account for delusions as beliefs that are epistemically irrational  (not well supported by evidence and not responsive to counter-evidence). As there are many beliefs that fit that description, such definitions fail to provide sufficient conditions for a belief to count as a delusion. Adding other clauses (that the delusion is idiosyncratic or that it is harmful in some way) may help provide sufficient conditions, but that means that it is not their irrationality that sets delusions apart from non-delusional beliefs. 

In a recent book chapter co-authored with Rachel Gunn and Ema Sullivan-Bissett, we observe how it is extremely challenging to distinguish delusions from non-delusional beliefs (such as alien-abduction beliefs and overly optimistic beliefs about one's own performance) on the basis of epistemic irrationality alone. One possibility is, of course, that what sets delusional beliefs apart is what Bell and colleagues call alterations to coalitional cognition.

Is the irrationality of delusions the source of their pathological nature?

Project PERFECT's aim was to argue for the often neglected fact that some epistemically irrational beliefs can be advantageous from a number of perspectives: psychological, pragmatic, even epistemic. One of the central case study was that of delusional beliefs. Despite delusions being characterised as the mark of madness, there are circumstances in which the adoption of a delusional belief turns out to be adaptive, albeit temporarily.

In two recent papers, I consider cases where adopting delusions can be beneficial. With Rachel Gunn, we notice that some delusions can be conceived as short-term protective responses to disruptive and traumatising life events, making some experiences more bearable for the person and providing a sense of purpose that keeps depression at bay in the short term. With Eugenia Lancellotta, we look at how delusional beliefs can count as psychologically adaptive in the context of diagnoses as diverse as schizophrenia, depression, and OCD. The delusion can support the person's agency at critical times.

That is why I applaud Bell and colleagues' attempt to move beyond the cognitive deficit models of delusions and I fail to recognise my view of delusions in the description of the 'dominant account' they provide. I do not have an account of what makes delusions pathological--and increasingly doubt the utility of the pathological vs. normal distinction when applied to beliefs--but I know that irrationality is not the answer.

I suspect that the reason why delusions are thought to be pathological where garden-variety irrational beliefs aren't lies in their being less widespread, in their not being shared in the same way in which optimistic beliefs about the self and, sadly, prejudiced beliefs are. This is not incompatible with the hypothesis about coalitional cognition: people with delusions do not 'fit in'.