Bortolotti's new book argues that many everyday, non-pathological beliefs are irrational. It follows from this that one cannot deny that delusions are beliefs by appealing to their irrationality alone. In this she defends what is known as the ‘doxastic’ conception of delusions, the view that delusions constitute full-fledged beliefs.
The readers of this Journal may find Bortolotti's project puzzling at first glance – the psychiatric mainstream (as reflected in DSM-IV) already accepts that delusions are beliefs, albeit unusual ones; and few will deny the possibility of irrational beliefs in the non-delusional. Yet clinical researchers interested in delusions have much to gain from this well-researched and empirically informed meditation on the many similarities between delusions and ‘everyday’ irrational beliefs – one driven as much by research on the reasoning foibles of the non-delusional as by work on psychiatric cases. While Bortolotti disappoints in not defending a positive definition of delusion, she offers a valuable resource (and considerable set of obstacles) to anyone pursuing that project.
Bortolotti's argument is summarized in a challenge she poses to deniers of the doxastic conception of delusions: ‘For each delusion, I'll give you a belief that matches the type if not the degree of irrationality of the delusion’ (p. 261) (All citations are to Bortolotti (2009) unless otherwise noted). Chapters Two, Three, and Four aim to fulfil this promise, each assessing the degree to which both delusions and ordinary beliefs meet the standard of a particular conception of rationality. Multiple examples are offered in each case; below I recount just a few to give the flavor of the dialectic. (Due to space constraints, I will not discuss the final Chapter Five, which takes up the issue of thought ‘insertion’ in schizophrenia; the book's core argument is contained in the earlier chapters).
The subject of Chapter Two is procedural rationality. One's beliefs fulfil the norm of procedural rationality to the extent that they are ‘well-integrated’ with one's other beliefs, in accordance with principles of good reasoning (be they logical rules of inference, principles of probability theory, or something else). The idea is simply that one's beliefs ought to ‘hang together’ as a coherent whole. Many delusional beliefs seem to flout this norm; an example is offered from Breen et al. (Reference Breen, Caine and Coltheart2000), where a patient claims that her husband died four years ago, while also insisting that he is currently a patient in the same hospital. As examples of non-delusional beliefs that violate the same norm, Bortolotti cites preference reversals in normal subjects: sometimes, whether a subject deems one option better than another changes depending on how the options are described, even when the different descriptions do not entail real differences in the options described (Tversky & Thaler, Reference Tversky and Thaler1990). In such cases one arguably has contradictory beliefs about whether a certain option is best. Also offered are the classic studies of Tversky & Kahneman (Reference Tversky and Kahneman1983), where subjects were given a description of a woman ‘Linda’ who is ‘outspoken’ and ‘concerned with issues of discrimination and social justice’. Asked whether it was more likely that Linda was a feminist bank teller, versus merely a bank teller, subjects replied that the former was more likely, even though a principle of probabilistic reasoning holds that A & B is never more likely than A by itself.
While these examples are not puzzling in the same way as the patient's claims about her husband, nevertheless they involve violations of the norm of procedural rationality. So, mere violation of that norm does not, Bortolotti argues, warrant concluding that the delusion is not a belief. One might respond that non-delusional subjects will revise their judgements when alerted to their procedural irrationality, while those with delusions typically do not. Bortolotti counters with data suggesting that normal subjects are also resistant to revising their prior judgements in such experiments, and notes that at least some delusional patients are able to revise their delusions through the aid of cognitive behavioural therapy.
Bortolotti next (in Chapter Three) discusses epistemic rationality, which governs the subject's relation to new evidence. Usually when one has formed a delusion (e.g. that one's spouse has been replaced by an imposter), there is overriding evidence available to the contrary. Yet, for whatever reason, delusional patients tend to overlook or refuse to accept this evidence. Bortolotti suggests that racist, self-serving, and religious beliefs, are similarly resistant to contrary evidence. If so, resistance to revision given appropriate evidence is not in itself reason to deny that delusions are beliefs. Bortolotti concedes that ‘in the typical case, [delusions] are epistemically irrational to a higher degree than non-pathological beliefs’; yet she insists we should resist the conclusion that delusions and epistemically irrational beliefs ‘are qualitatively different’ (p. 114).
Agential rationality is the last rational norm discussed (in Chapter Four), relating to the subject's capacity to provide reasons in defence of her beliefs, and to act appropriately upon them. Asked why he believes his wife has been unfaithful, a delusional man responds that the fifth lamp-post along the left is unlit (Sims, Reference Sims2003). A patient who views doctors and nurses as poisoners may nevertheless happily eat the food they give her (Gallagher, Reference Gallagher, Broome and Bortolotti2009). These are violations of agential rationality – the first being a failure to give (good) reasons for one's beliefs, the second a failure to have one's actions appropriately guided by the delusional belief. As non-delusional counterparts, Bortoltti offers Nisbett & Wilson's (Reference Nisbett and Wilson1977) subjects, who gave confabulatory reasons for choosing one of four identical pairs of panty-hose to be of the best quality (they were told initially that each pair was different, and asked to choose the best). While these subjects offered reasons for their preferences, Bortolotti's claim is that their reasons were not intersubjectively good reasons (for the delusional patient has his reasons as well – an ‘unlit lamp-post’). Hypocritical beliefs are offered as evidence of non-action-guiding beliefs in normals; for example, college students profess a belief in the dangers of unprotected sex, yet fail to wear condoms (Aronson, Reference Aronson, Harmon-Jones and Mills1999). Further, it is noted that some delusions are indeed action guiding. The Cotard's patient, suffering the delusion that he is dead, may fail to bathe or react to negative stimuli, remaining mute or speaking ‘in sepulchral tones’ (Weinstein, Reference Weinstein, Halligan and Marshall1996).
For all of the interesting parallels Bortolotti draws between delusions and everyday irrational beliefs (and the above only scratches the surface), it is hard to shake the sense that there remain important differences in degree concerning how seriously most delusions violate rational norms, compared to non-delusional irrational beliefs. As already noted, Bortolotti often accepts these differences in degree, insisting that they are not significant enough to force us to place delusions outside the realm of belief. Fair enough, one might respond, but provided we are committed to helping people with delusions either way, why should we care whether we place delusions with belief itself, instead of (due to their extreme irrationality) with the merely belief-like? After all, Bortolotti is not advocating the radical thesis that delusions are a false or scientifically vacuous category (although her book provides fodder for someone with that agenda). Nor does she offer reason for thinking that treating delusions as merely belief-like will have very different consequences for the treatment of delusions than if they are considered ‘full-fledged’ beliefs. Why, then, is it critical to establish that delusions are beliefs, and not merely belief-like?
One motive might stem from a desire to provide a formal definition of belief (and of delusion). Showing that delusions are beliefs might be used to show that rationality, as a psychological construct, can be cleanly separated from belief. That would be an interesting result. But establishing it would require defending a positive account of what it is to be a belief, and Bortolotti emphasizes that ‘what determines whether a mental state is a belief is a question whose scope exceeds our ambitions here’ (p. 74). Without such an account in place, the critic is free to reply that rationality comes in degrees, and that for a mental state to be a belief it must be more rational than delusions.
Bortolotti would likely reply that some delusions are no more irrational than some mental states that we are happy to call beliefs. Perhaps, but once we are being careful about things, is it really so clear that all of the putative non-pathological yet irrational beliefs discussed really are beliefs (e.g. do the college students really believe that unprotected sex puts them at risk, or do they do they just know they are supposed to say it does)? The underlying problem is that, while the book's core argument is that delusions are beliefs, neither a formal definition of belief nor of delusion is attempted. So it is difficult to know how much rides on each specific example; some can perhaps easily be explained away as differences in degree (or in some other way), others perhaps not.
A last puzzling feature of the work is Bortolotti's tendency to slide from the thesis that some beliefs are irrational (relatively uncontroversial) to the radical thesis that most beliefs are irrational (very controversial!). ‘Delusions do not behave like rational beliefs’, she tells us, ‘but most beliefs do not behave like rational beliefs either’ (p. 120). In admitting she has not identified what is distinctive of delusions, she notes, ‘they are irrational, as most other beliefs are’ (p. 243). It would be big news if most beliefs were shown to be irrational; it is hard to see why Bortolotti thinks she has shown it. It is one thing to offer evidence that, for each of a variety of rational norms, there exist beliefs that violate it; it is quite another to show that most beliefs violate at least one such norm. My guess is that Bortolotti would like us to leave her book with the impression that the irrationality of delusions has relatively little to do with their status as delusions. This might be plausible if most beliefs were irrational (although, again, there would still be questions of degree to address). But if most beliefs are not irrational, then understanding the irrationality of delusions may yet be a key to understanding the nature of delusions generally, even if it is not the whole story.
Despite these problem areas, the book's clarity of organization and argument make it well suited to the interdisciplinary audience at which it aims. Empirically minded philosophers, psychologists, and psychiatrists will enjoy Bortolotti's thought-provoking synthesis of the literatures on delusional reasoning and on ‘everyday’ irrational thought. She sheds welcome light on the complex relation between irrationality and mental pathology.
