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Interview with Federico Bongiorno on Delusions

In this post, I interview Federico Bongiorno who recently completed a doctoral project on delusion formation at the University of Birmingham.


Federico Bongiorno



LB: Philosophers are intrigued by delusions. What interests you about them?

FB: There are several things that interest me about delusions, which is part of the reason why I decided to write a PhD thesis comprising of self-standing papers rather a single book-like package. I will focus on just one, the question of whether delusions can be beliefs despite being only marginally belief-like.

Participants in this debate are typically non-committal as to what beliefs are over and beyond our folk-psychological practices. So, when they ask whether delusions are or aren’t belief-like, what they want to know are things such as whether delusions play the same role as beliefs in predicting intentional behaviour, or whether they conform to the stereotypical cluster of attributes (cognitive, behavioural, phenomenal) that we would normally expect beliefs to manifest.

An aspect that has so far been largely neglected in the debate is whether delusions really are beliefs, whether there is any robust and unitary psychological entity to simultaneously fill the role set by our folk concepts of ‘belief’ and ‘delusion’. Are beliefs objects that function within scientific theories, or are they merely part of folk psychology? And are delusions belief-like in a scientific psychological sense, strictly in a folk psychological sense, both, or neither?

Addressing this gap is important, I think, for the at least the two following reasons.

First, we need to ensure that the folk concept of belief is not in conflict with the scientific kind at work in psychology and cognitive science. For otherwise, we should allow for the possibility that delusions may be consistent with one but not with the other, or vice versa.

Second, if we can make lawlike generalisations about the ways we normally fix, update, and store beliefs, then we are in a position to really tell whether the surface features of delusions are features of beliefs.

The hypothesis I explored in my PhD thesis was that delusions are the way they are, deviate from rationality in the ways they do, because of how beliefs function cognitively under highly irregular circumstances, such as anomalous sensory experiences and attentional abnormalities.

So, one thing that interests me which very few people seem to be talking about is whether the status of delusions as beliefs can be assessed outside the folk-psychological discourse, and independent of our regular sayings about belief.

LB: Some philosophers claim that delusions are endorsements of experience and other philosophers argue that delusions are explanations of the experience. What is the difference between these accounts? 

FB: One idea that has been very popular in cognitive neuropsychology and neuropsychiatry is that delusions arise as subjectively adequate responses to abnormal sensory experiences, of sight, hearing, or whatever. Call this view ‘empiricism’. Empiricism comes in at least two variants that differ concerning the specific mode in which delusions are grounded in experience: the explanationist account and the endorsement account.

As you said, on the explanationist account, delusions serve an explanatory function, they arise inferentially from one’s reasoned attempt to explain an abnormal experience. On the endorsement account, delusions are acquired immediately, non-inferentially, from experience when one takes that experience at face value.

We can illustrate the difference between these two accounts using the example of Capgras delusion, in which a close relative or spouse is believed to be a stranger and to have been replaced by an identical imposter. Both sides agree that the Capgras delusion involves an abnormal experience in response to seeing a familiar person. What is at issue is the degree of continuity between the representational content of the experience and the content of the delusion itself.

Proponents of the explanationist account will say that the content of the experience is relatively nonspecific. For instance, the experience might be a coarse-grained feeling that something is off about the person being looked at, and one would hit upon the delusional hypothesis to make sense of why the person feels off, e.g., she does because she’s not who she looks like.

By contrast, proponents of the endorsement account will take the content of the experience to be closely linked, if not identical with, the delusional content. For instance, they might think that the reason why a subject believes that the person in front of them is a stranger is because they have in fact an experience representing that person as a stranger. 

LB: Which account do you prefer? 

My preliminary answer would be neither and both. 

What I mean is that we don’t have to choose one: we can use whichever seems most appropriate depending on context. For instance, if someone believes that they are possessed by the devil because they hallucinate voices telling them to kill God, their belief is probably going to be an explanation of experience. On the other hand, if someone believes they have a second head because they hallucinate a second head, that is probably going to be an endorsement of experience.

Something else to keep in mind is that you could in principle have hybrid cases of delusions formed from a combination of endorsement and explanationist processes. Indeed, some think the Capgras delusion might be one such case: the subject would literally experience a person as a stranger at some first moment in time, and later infer that the person is an imposter to explain why she looks so much like a loved one.

So, on balance, there is no reason why we should give up one view and keep the other, given that both potentially help explain delusions.

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