Tuesday, 20 March 2018

What Makes a Belief Delusional?

In December 2016 an exciting volume entitled Cognitive Confusions: Dreams, Delusions and Illusions in Early Modern Culture has been published by Legenda. The book, edited by Ita McCarthy, Kirsty Sellevold and Olivia Smith, contains a chapter authored by Ema Sullivan-Bissett, Rachel Gunn and myself on the challenges we face when we want to tell delusional beliefs apart from other beliefs.

We start with the standard DSM definition of delusions, and explain that clinical delusions are characterised by surface features of two kinds, epistemic (fixity, implausibility) and psychological (negative impact on functioning). Then we ask whether we can decide whether a type of belief is delusional by using those criteria. We consider three cases of belief that match at least some of the criteria: the belief that some thoughts have been inserted in one's mind by a third party; the belief that one has been abducted by aliens; and the belief that one is better than average at just about everything.

Discussing the similarities and differences among such beliefs -- Are they based on evidence? Are they common or rare? Do they bring any benefit? Do they help explain anomalous experience? -- is relevant to two projects that have been featured on this blog before: the Costs and Benefits of Optimism project and the PERFECT project. In the end, our goal is to show that neither the epistemic nor psychological features mentioned in the definition of delusions can help us sort delusional beliefs from non-delusional ones. Some delusions do not meet the criteria and some beliefs that we would not class as delusions do.

Rachel Gunn (PhD student at the University of Birmingham, working on delusions) examines the phenomenon of thought insertion by using very interesting first-person reports by people who used internet forums to share their unusual experiences. She observes that the experience affects people in different ways. For some but not for all the thought is felt like an unwelcome intrusion. For some but not for all the content of the thought also generates a compulsion to think or do certain things. Thought insertion is regarded as a symptom of schizophrenia, but whether it involves a pathological experience, whether it is a delusional belief, or whether it is harmful cannot be established without reflecting on the specifics of the individual case.

Here is one of the first-person reports Rachel analyses:
i truly do have unwanted thoughts that are forced into my head from somewhere... I mean I will have a thought saying my grandmother is a bitch. I would never ever think of my grandmother as a bitch. She is one of the greatest women I know and I adore her. So how is that a delusion? It is an intrusive thought! I sure didnt imagine it!.... i really do not think my grandmother is a bitch. i think these thoughts are evil and came from an evil being. Some thoughts however that pop into my head all of a sudden are my own thoughts and i can recognize that even though they are unwanted, but some are just plain ridiculous and mean and i know must be from an outside force. 
Star-28, ‘Forum’, Mental Health Forum (2010)

Thursday, 15 March 2018

Unbelievable Errors

This post is by Bart Streumer. Bart Streumer is Professor of Philosophy at the University of Groningen. In this post he introduces his book Unbelievable Errors, which has recently been published by Oxford University Press.

Widespread beliefs can be systematically mistaken. Take religious beliefs: if God does not exist, these beliefs are all mistaken. But you may think that some widespread beliefs cannot be mistaken in this way. For example, consider normative judgements: our beliefs about what is right or wrong, or about what there is reason to do or to believe. Could these beliefs be systematically mistaken?

In my book Unbelievable Errors, I argue that they are. I argue that normative judgements ascribe normative properties, but that these properties do not exist. This means that all normative judgements are false. For example, the belief that stealing is wrong ascribes the property of being wrong to stealing, but this property does not exist, which means that this belief is false. The belief that stealing is permissible ascribes the property of being permissible to stealing, but this property does not exist either, which means that this belief is false as well. And similar claims apply to all other normative judgements.

The view I defend in the book is known as ‘error theory’. Some philosophers accept such a theory about moral judgements. But the error theory about all normative judgements that I defend may seem so bizarre as to be simply incredible. I agree. For in addition to defending the error theory, I also argue that we cannot believe this theory. If I am right that the theory is true of judgements about reasons for belief, the theory entails that there is no reason to believe the theory. I therefore think that we only really believe the error theory if we believe that there is no reason to believe the theory. And I argue that we cannot do this: we cannot have a belief while at the same time believing that there is no reason for this belief. If so, it follows that we cannot believe the error theory.

If I am right that we cannot believe the error theory, the arguments I give in my book cannot convince anyone that this theory is true. That is why I have called the book  Unbelievable Errors. But the fact that an argument cannot convince us does not show that this argument is unsound. Moreover, I argue that our inability to believe the error theory actually makes the theory more likely to be true, since it helps to answer objections to the theory, it makes it harder to reject the arguments for the theory, and it undermines revisionary alternatives to the theory. I therefore think that our inability to believe the error theory is an advantage rather than a problem for the theory.

When we have mistaken beliefs, it is normally possible for us to see that these beliefs are mistaken. But this may not always be possible. If I am right, our normative judgements are systematically mistaken in a way that we are unable to see.