Suppose a man goes to see his psychiatrist complaining of anxiety and depression and, when asked what was making him anxious and depressed, replies that it was because his wife was having an affair with a man in the office where she worked. Suppose there follows a discussion between clinician and patient about the patient's reasons for believing that his wife was being unfaithful to him. Suppose the reasons the patient offers include such things as “She wears a different dress every day, and she always puts on makeup very carefully each morning” and “Sometimes she phones me to say she has a deadline to meet at work and has to stay behind for an hour, and then she does come home an hour later than usual.”
These don't seem to be very convincing reasons, and the other reasons the patient proffers are no more convincing, so the clinician begins to doubt the reasonableness of the patient's belief. Hence the clinician follows this up by asking the patient whether he has taken any steps to verify his belief. The patient says that he has; that on various occasions he has hidden outside his wife's place of work to see whether she ever leaves in the company of a man. Asked whether he had ever seen her do this, he says “No, she has always left by herself,” but then volunteers the comment that he must have been unlucky in his choice of days; indeed, he mentions, he once performed this stakeout every day for a week, with negative results, which, he adds, must have meant that the male coworker concerned had been away from work that week. The patient also mentions that he has confided his worries about his wife's infidelity to his children, who pointed out to him that his reasons for the infidelity belief are flimsy in the extreme, and urged him to abandon the belief; but this has made no difference to the strength of his belief.
Given that this man cannot produce a single piece of evidence that plausibly supports his belief, and given that, even though the results of his investigations have been uniformly negative, this has not shaken him in the belief, does it not seem natural to regard this belief as a delusion? Similarly, might we not expect the clinician to conclude that this patient needs treatment? If we answer both of these questions in the affirmative, what is our reason for this? The answer is obvious: it's because this man has a belief that is held (a) with strong conviction regardless of the counterevidence and (b) despite the efforts of others to dissuade him.
Now suppose that, some years later, the clinician discovers that the man's belief was true after all: His wife had been having an affair at that time, and indeed it was with that particular male coworker. Does that mean that it had been a mistake to consider the patient's belief as a delusion? If the essence of the concept of delusional beliefs is that they are beliefs that are strongly and incorrigibly held in the absence of adequate grounds for doing so, then no mistake was made. It would have been very strange if at that time the clinician had mentally noted: “Before I decide whether this man needs treatment, I will have to find out whether or not his wife really is having an affair.”
I consider that this example shows that, when one is classifying a particular belief as a delusion or not a delusion, whether the belief is true is irrelevant. What is relevant is whether the grounds for the belief are good enough. They weren't good enough in the case of our delusionally jealous patient (even though his belief, as it happened, was true).
What are the implications of this conception of delusion for the target article? First of all, the infidelity scenario is a specific example of a general possibility accepted by McKay & Dennett (M&D): that “ungrounded beliefs [can] be serendipitously true” (sect 1, para. 2; though the positive connotation of “serendipitously” is not quite right here; something like “accidentally” is needed). But, importantly, they note that they will not consider such ungrounded beliefs as misbeliefs. So our patient's belief about his wife's unfaithfulness does not count as a misbelief for M&D. If so, it isn't clear what they mean by “misbelief.” The first sentence of their article says, “A misbelief is simply a false belief.” Later they acknowledge that false beliefs can be well-grounded and true beliefs can be held with no grounds, so that truth and groundedness are independent. Which of these two is critical for characterizing their concept of misbelief? Is a belief that is very well-grounded but false a misbelief?
Later on in the introduction of their article the authors offer a tentative taxonomy of misbelief: “those that result from some kind of break in the normal functioning of the belief formation system and those that arise in the normal course of that system's operations” (sect. 1, para. 4). But in neither case does the method via which the belief is generated guarantee that the belief is false; it might be true – in which case it doesn't count as a misbelief.
What, then, is the difference between misbelief and false belief? If all misbeliefs are false beliefs, and if “misbelief” and “false belief” are not synonymous, then there must be false beliefs that are not misbeliefs. What criterion classifies false beliefs into those that are misbeliefs and those that are not?
At the beginning of section 4, “Doxastic dysfunction,” the authors write: “delusions are misbeliefs par excellence – false beliefs that are held with strong conviction regardless of counterevidence and despite the efforts of others to dissuade the deluded individual” (sect. 4, para. 2). The example with which I began this commentary was of a belief held with strong conviction regardless of the counterevidence and despite the efforts of others to dissuade the individual holding this belief. Do M&D want to say that, in the scenario that I outlined, the patient's belief about his wife's fidelity doesn't count as a delusion – just because it happened to be true? The requirement always to establish the objective falsity of a belief before offering a diagnosis of delusion would wreak havoc in the profession of psychiatry.
