Delusions, Harmful Dysfunctions, and Treatable Conditions


It has recently been suggested that delusions be conceived of as symptoms on the harmful dysfunction account of disorder: delusions sometimes arise from dysfunction, but can also arise through normal cognition. Much attention has thus been payed to the question of how we can determine whether a delusion arises from dysfunction as opposed to normal cognition. In this paper, we consider another question, one that remains under-explored: which delusions warrant treatment? On the harmful dysfunction account, this question dissociates from the question about dysfunction—there are a broad range of “treatable conditions” beyond mere harmful dysfunctions. As such, many conditions that arise from normal cognition are also eligible for medical intervention. We argue that some delusions that arise from normal cognition may well fall under the banner of treatable conditions. We examine the practical and ethical questions surrounding such treatment, including the issue of coercive and deceptive treatment options.

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  1. 1.

    At various points, Sakakibara seems to be talking only about the question of when coercive treatment is warranted, but at other points he includes any kind of “medical intervention,” and on one occasion (p. 155) appears to run together the question of pathology and treatment when discussing the potential dysfunctionality of delusional jealousy. In The Uncertainty Surrounding Dysfunction in Delusions we show why it is particularly problematic to link treatment to dysfunction in the case of delusions, and in Treatment Types: A Role for Dysfunction after all? we discuss how this relates to coercive treatment. Whatever Sakakibara’s original intent, the idea raises interesting questions that are worth exploring.

  2. 2.

    A previous attempt can be found in the work of Miyazono [2]. We think that Sakakibara’s work is an improvement on this attempt, mostly for the explanatory power cited in Explanatory Power. Miyazono tends to downplay the idea that delusions are symptoms, and that symptoms can often arise in the context of normal functioning, which we think is a key observation about delusions.

  3. 3.

    We should point out that we think this is an unnecessary dichotomy: “physical” symptoms can arise in the course of normal functioning, though it is true that this problem is more common and more difficult to resolve for mental symptoms.

  4. 4.

    For discussions of delusions and the relation to pathology, see [2, 8, 12].

  5. 5.

    For our purposes, we take it that delusions are beliefs, which is the general clinical and scientific conception. For an overview of some philosophical debates, and an argument in favour of the doxastic conception of delusions, see [20].

  6. 6.

    Similar sentiments have been expressed by others:

    Understanding psychopathology based on an analysis of harmful dysfunction will therefore not be relevant from a practical clinical perspective without an evolutionary psychology of normal functional psychological mechanisms as well as psychopathology—that is, a science of function is necessary to define dysfunction. Whether or not something has an evolved function is currently not a question that may be easily resolved—the mapping of our adaptations has only just begun. [34, p. 453]

    evidence does not yield a clear demarcation between normality and disorder for mood phenomena, and the evolutionary literature does not much aid in delineating the boundary either. We may have to accept that much of what we currently identify as clinical depression cannot be shown to be dysfunction, and moreover that the clear presence of dysfunction cannot be used as the criterion for applying or withholding medical attention. [35, p. 212]

    it might be true one day—though it isn’t true at present—that our theories about how normal cognitive processes operate have become so detailed that they make predictions about whether particular treatment techniques will or won’t be effective. If that day comes, then treatment studies will be relevant to theories about normal cognitive, and cognitive neuropsychology will be directly concerned with issues involving treatment. [14, p. 4]

  7. 7.

    Sakakibara [3, p. 154] does not refer to this delusion by name, but the description matches delusional cases of reverse-Othello.

  8. 8.

    This complex relation between dysfunction and treatment is the reason we earlier (The Uncertainty Surrounding Dysfunction in Delusions) raised issue with Sakakibara’s inference from successful “treatment” to the existence of underlying dysfunction: treating a symptom does not indicate an underlying dysfunction, since it is possible to treat normal as well as dysfunctional symptoms, sometimes through the exact same method. The inference from successful “treatment” to underlying dysfunction is considered a complete misstep on the harmful dysfunction account [66, pp. 839-840]. On this note, we should say that we think the “bizarreness” and “un-understandability” clues mentioned by Sakakibara are likely the most useful: symptoms being out of context or inexplicable when placed within an appropriate examination of the patient’s life and social environment are the kinds of clues that the HD account sees as generally most useful—though still fallible—in the attempt to discern dysfunctionality [68].


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Clutton, P., Gadsby, S. Delusions, Harmful Dysfunctions, and Treatable Conditions. Neuroethics 11, 167–181 (2018).

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  • Delusion
  • Treatment
  • Symptom
  • Dysfunction
  • Disorder