Belief as Delusional and Delusion as Belief

Richard Mullen and Grant Gillett (2014) decry the oversimplifications that accompany ‘doxastic’ analyses of delusion analogizing them to belief states; particularly, they object to the recent elevation to the status of paradigmatic the ordinary beliefs often understood, in Bayesian terms, as probabilistic estimates of empirical facts. Such an approach ignores the significance of the delusion for the individual, they emphasize, neglecting the delusional person’s conceptions of self and identity in relation to the world. In support of their plea for a broader, more nuanced, and more clinically and existentially sensitive understanding of delusion, Mullen and Gillett enumerate drawbacks to the doxastic view not hitherto noted by its other critics, and explore generalizations about the delusional person’s thought as enactment, and the dualities in her frame of mind.

I agree with several conclusions reached in this discussion, and respectfully accede to the authors’ clinical knowledge when it comes to the extent to which delusions can only be understood, let alone treated, in terms of the rest of the subject’s irreducibly evaluative attitudes about self and world. I also share the view, demonstrated here, that normal belief states vary so much, in so many dimensions, that attempts to define delusions in contrast to them by appeal to their truth value, or how they have been acquired or maintained, will face daunting double counterexamples at every turn. (Against generalizations to the effect that all delusions and no non-delusions possess some trait, double counterexamples take the form: some delusions lack trait X, and some non-delusions possess it.) That said, I am not entirely persuaded by the reasons provided by Mullen and Gillett to cast doubt on doxastic analyses of delusion, and the following remarks primarily concern those.

Doxastic analyses of delusion have several drawbacks, our authors note. They may “fail to explain the often debilitating nature of delusions”—and that, I concede (above). But two other drawbacks remain: such analyses imply that “psychiatry is in the business of determining and regulating the acceptable limits of human belief” and they may result in the misidentification of other strong beliefs as delusional (Mullen and Gillett 2014, 27).

What is (and should be) the business of psychiatry? Well, primarily, healing: the alleviation of symptoms through treatment—on this, Mullen and Gillett would presumably agree. Nonetheless, it seems to me that when delusions are involved psychiatry is inevitably also in the business of determining and regulating the acceptable limits of human belief—although not as its primary end, and not in such a way as to violate the patient or compromise the clinician. This is because delusional thinking is flawed thinking as it is understood in clinical traditions, and linked to conceptions of normative rationality from the epistemology of the modern era (Radden 2011). Within those conceptions, from which our ideas about delusion and interpretation of the phenomena largely derive, rationality works not as a value-neutral property, but as a regulative ideal. And because they have long been assigned the part of contraries to what is accurate, true, and rational, and as inversions of attempts to define knowledge as true justified belief, conceptions of delusion reflect those evaluative norms. (Their origins within normative ideas about rationality explain the apparently incommensurate ways delusional status seems to be assigned, several of them illustrated in the clinical definition quoted by Mullen and Gillett [2014]). These include (i) being ideas that are false; (ii) being idiosyncratically and incomprehensibly private to the subject; (iii) having been acquired through reasoning that eludes others; and/or (iv) being maintained in ways that transgress norms of confirmation and disconfirmation (e.g., with inappropriate tenacity in the face of countervailing evidence). This range illustrates the contingent and historical origins of conceptions of delusion, it seems to me, and the role of delusions as opposites, derived from equally incommensurate accounts of rationality.¹

The link with normative rationality may not be a merely historical accident, of course, for rationality itself likely has adaptive value. As it is understood in these...