This post is by David Miguel Gray (pictured above), currently Assistant Professor of Philosophy at Colgate University and in the Spring of 2017 will be Assistant Professor of Philosophy at the University of Memphis. David’s research interests are in the philosophy of cognitive psychology (in particular cognitive psychopathology), as well as philosophy of mind, and philosophy of race and racism.
In this post David will address some theoretical issues with n-factor accounts of monothematic delusions. This post, and his previous one, will draw on his recent paper ‘Failing to self-ascribe thought and motion: towards a three-factor account of passivity symptoms in schizophrenia’, published in Schizophrenia Research.
Cognitive-level theories of monothematic delusions have become heavily discussed, significantly in part to the work of Max Coltheart, Robyn Langdon, and Martin Davies (e.g. see Davies and Coltheart 2000, Davies et al. 2001, Coltheart et al. 2007, Coltheart 2013). Theirs is a ‘two-factor’ theory in that it claims there are two impairments that must be explained for all monothematic delusions. The first factor that must be explained is why a delusional hypothesis is a 'prima facie reasonable response to the subject’s experience' and the second factor to be explained concerns how one can adopt and maintain a delusional hypothesis given its 'utter implausibility and the uniform skepticism with which other people greet it' (Davies and Coltheart 2000).
Leaving the second factor aside, I argue that the explanatory project involving the first factor is ill defined in that it combines the requirement to explain cognitive abnormalities (viz. abnormal experience) with the requirement to explain the inferential process that results in a delusional hypothesis. Whereas the first of these explanatory demands counts as a ‘factor’, as defined above, the second may or may not, depending on whether the inferences that lead to the delusional hypothesis could be described as abnormal. Other n-factor theorists (e.g. one factor theorists like Phil Corlett and two factor theorists like Coltheart), think these inferential processes are normal and rational. I agree. So why is explaining these processes important?
There are three benefits for providing an account of rational processes. First, explaining rational inferences which lead to delusional hypotheses is necessary for a complete cognitive-level explanation of any monothematic delusion. Second, realizing what does not have to be explained by abnormal experience—what can be instead explained by implicit inference—helps us appropriately characterize the nature of the abnormal experiences we are investigating. Third, even if the inferences involved in this step of our causal explanations for some monothematic delusions are normal, it could be the case that in some monothematic delusions, they are not (perhaps in all of them if we have not gotten our explanations right). By presuming at the outset that such aspects cannot be ‘factors’ (i.e. involve abnormalities), we have eliminated potential avenues of research in our framing of the issue.
In my article I argue why there are two distinct explanatory projects required for giving a cognitive explanation of a delusional hypotheses:
What delusional proto-hypothesis can be understood as a prima facie reasonable response to the subject's abnormal experience?
and
How can we explain the development of a delusional hypothesis in light of the subject's delusional proto-hypothesis, inferences, normal experiences, and background information?
A ‘proto-hypothesis’ is just an explanatory construct which can be thought of as a reasonable response to a subject’s abnormal experiences (without any inferences, rational or otherwise). This proto-hypothesis would be something like the most accurate characterization of the abnormal experience, simpliciter, in a monothematic delusion.
The second explanatory project leaves it open whether or not the inferences involved in delusional hypothesis formation are abnormal. (I take it inferences can be good or bad and still be within normal reasoning – e.g. faulty inferences drawn in Wason selection tasks. What would make these inferences pathological is if they deviate in principled ways from normal reasoning, good or bad.) Regardless of whether the inferences are abnormal, meeting the second explanatory goal helps us characterize abnormal experience.
Returning to my claim above, why should we think that abnormal experience alone is insufficient for providing prima facie justification for a delusional hypothesis? Delusional hypotheses are normally complex enough that they outstrip what experience alone could justify. Having a weak autonomic response when I see my wife does not provide prima facie justification for the delusional hypothesis that my wife has been replaced by an imposter; although, it might provide prima facie justification for the proto-hypothesis that I have low emotional arousal in front of what appears to be my wife.
I take it that experiences which would justify proto-hypotheses can more easily be correlated with mechanisms (e.g. weak autonomic responses) that give rise to abnormal experiences. I take it that this is a good thing. If we had to assume that abnormal experiences were complex enough to justify delusional hypothesis, making correlations between abnormal experiences and the mechanisms that are supposed to explain them would be all the more difficult. Would it even be possible to have an experience that, in isolation from inferences, could be described as a my-wife-has-been-replaced-by-an-impostor experience? Furthermore, could we correlate such a complex abnormal experience with just a weak autonomic response? As mentioned above, explaining these inferential steps will aid us both in providing a better explanation of delusional hypotheses and in providing more plausible accounts of the nature of abnormal experience.
Providing detailed explanations of each kind of monothematic delusions requires different explanations, even with the commonalities among them. While providing an account of thought insertion and alien control was my main purpose, I hope that in the paper I have shed a bit of light on the explanatory demands that monothematic delusions could place on us.
One quick clarification: my calling for a three-‘factor’ account is not necessarily in conflict with two-factor accounts. Coltheart has mentioned on this blog (unfortunately for me after my paper came out) that his use of ‘factor’ does not signal explanatory steps but the kinds of errors that must be present for monothematic delusions. I’m in agreement that in at least the cases I have considered, the inferences I have given are reasonable in light of the given experiences (although I take these inferences to be better explained as deductive, rather than abductive).