The Mental Disorder: What Kind of Kind?
This reflection on the biopsychological focus of the RDoC initiative brings us to the question as to what mental disorders exactly are: should different disorders be thought of as species that have a status parallel to what biologists discern in the natural world? Or is such a claim overrated? And are the conventional labels invented by professionals over the years above all artificial? As already indicated in the previous section, the DSM seems to assume that mental disorders are natural kinds. The idea of natural kinds has a long-standing history in philosophy. As Rachel Cooper (2005, p. 46) indicates: “‘Natural kind’ is a technical term used by philosophers to refer to the kinds of thing or stuff studied by the natural sciences.” H2O, bonobos, and birch trees are examples of natural kinds: all have a fixed structure that can be discovered by means of empirical research, and they behave according to natural laws. Independent of what people think about these objects, and of how such objects are appreciated by humans, natural kinds function along fixed laws. Traditionally, the concept “natural kind” was used in contrast with “artificial kinds,” which referred to artifacts of human work. However, some of these artifacts, like machines and lab-designed chemicals, also have a fixed structure, and behave according to stringent laws, which is why they cannot be simply separated. In his review of the “natural kind” concept, Ian Hacking (2006) indicates that so many contradicting claims about natural kinds circulate in literature that the concept itself has self-destructed. He indicates that “kinds,” which are things, states, or events that we call with the same name (e.g., “ trees,” “dogs,” “depression”), are always distinguished by classifying human beings, and that the degree to which these are natural or not is variable. Discussions about natural kinds started in the Victorian era, when scientists were highly concerned with classifying the many objects they discovered (plants, animals, stones, etc.) in taxonomies. Typically, at first taxonomies are seen as artificial and pragmatically useful grouping schemes. Yet, as time evolves such schemes are often taken as reflections of nature itself, which illustrates our common tendency toward reifying interpretation. Hacking argues that qualifying kinds as “natural” or not is illusory. Indeed, each classification reflects choices and preferences. The degree to which a kind is natural depends on our natural scientific insight in the phenomenon under study. Therefore, in line with William Whewell, he defends the following characterization, which above all stresses the pragmatic value, logical coherence, and empirical correctness of classifications: “a kind is a class denoted by a common name about which there is the possibility of general, intelligible and consistent, and probably true assertions” (Hacking 2006, p. 34).
No matter how abstract the question as to whether mental disorders are natural kinds might be, it is an issue with direct impact since it defines the public and scientific status of psychiatry. Indeed, often the adjective “natural” is taken as a quality label that is presumed to define the public and scientific status of the kind one is interested in: “If mental disorders are natural kinds then there will be laws, explanations and sound inductive inferences in psychiatry—in short psychiatry will be a genuine science. If on the other hand mental disorders are not natural kinds, whether psychiatry is a science must be questioned” (Cooper 2005, p. 46). As discussed in Chap. 2, in the 1970s critical scholars questioned the scientific status of psychiatry and by pointing to labeling and reification they cast serious doubts on the so-called natural kind status of mental disorders. They paid the price of being damned and extradited by the psychiatric establishment and were eventually overruled by the neo-Kraepelinian restoration movement.
Indeed, the issue of the kind of thing a mental disorder is needs to be approached carefully. As a first possibility, mental disorders might be thought of as essentialist kinds. Within this view, mental disorders are indeed natural kinds and a single underlying reality is presumed to be at the basis of each disorder. Disorders then differ in that they obey different natural laws and they exist in reality regardless of whether we detected them or not: “essentialist kinds have essences, and they exist whether or not we recognize them” (Kendler et al. 2011, p. 1144). Essentialist accounts of natural kinds assume that well-defined biological etiologic disturbances are to be found at the basis of mental disorders, like specific deficiencies in the brain or genetic defects. The roots of such essentialist disorder accounts can be found in anatomo-pathological explanations of disease. In 1822, the French physician Antoine Laurent Bayle described the disease of general paralysis. Qua syndrome, general paralysis is characterized by delusions that normally start with exaltation. Throughout the years these fade out; the individual ends up with deterioration, amnesia, and dementia. Bayle argued that general paralysis results from a chronic inflammation of the brain. Later on, in 1913, the Japanese bacteriologist Hideyo Noguchi demonstrated that the bacterium that causes syphilis (Treponema pallidum) affected the brain tissues of paralytic dementia patients. Moreover, 30 years later penicillin proved to be an effective medicine for treating the Treponema pallidum bacteria, and the once prevalent neurosyphilis quickly became a rare disease. This discovery was idealized, fueling the belief that similar unequivocal essences could be found at the basis of all mental disorders. However, what was obfuscated by this idealization was the fact that only a limited number of untreated syphilitic patients actually develop general paralysis, meaning that the actual cause of neurosyphilis is not as straightforward as the essentialists might have hoped (Verhaeghe 2002).
Nowadays, such essentialist accounts are considered naive: “In the 19 th and early 20th centuries, the successful demonstration of a single infectious etiology for general paresis of the insane led to the idea that single, discrete causes might exist for other major psychiatric disorders. Over a century of increasingly sophisticated neurobiological research has failed to fulfill this vision” (Kendler et al. 2011, p. 1144). For example, contrary to what was first hoped, genes are no longer considered to be such candidate essences: “no genetic marker has yet been shown to be useful in prospectively identifying any specific psychiatric disorder” (Dubovsky 2016, p. 130; see also McNally 2011). Nonetheless, the tendency to essentialize mental disorders is deeply ingrained in the lines of reasoning of both laymen and professionals (Adriaens and De Block 2013). Indeed, the DSM-5 also seems to flirt with such a naive essentialist view of mental disorders. This is reflected in the claim that the DSM-5 aimed “to carve nature at its joints” (Regier et al. 2009, p. 648). The idea of “joints in nature” suggests that the world of psychopathology contains a well-defined fixed internal structure that simply awaits scientific discovery. Such a view bears witness to an essentialist model of mental disorders (Kendler et al. 2011; Lilienfeld and Marino 1999). The idea that “diagnoses in the DSM-III, DSM-III-R, and DSM-IV are best understood as useful placeholders ’ (Bernstein 2011, my italics) while the DSM-5 provides us with validated alternatives also bears witness to naive essentialism. The idea of the placeholder suggests that one day the “real category” will replace the artificial label. Given the fact that the DSM-5 doesn’t differ much from its predecessors, one cannot but conclude that the manual attempts to keep the essentialist dream alive, while in actual fact it by no means lives up to the standard it aspires for.
In contrast with essentialist natural kind accounts, forms of psychopathology could also be thought of as practical kinds (Zachar 2002). Resting on the philosophical ground of pragmatism, the practical kind account assumes that no unambiguous reality can be found in the world that simply awaits discovery. Indeed, several valuable ways of cutting the world up could be designed, albeit some classifications have better practical implications than others and hence should be favored. As Peter Zachar (2002, p. 219) indicates: “The practical kinds model does not deny that things have internal structures; it only denies that internal structure by itself determines category membership.” What really matters in terms of developing pragmatic classification systems is what one can do with them. For example, in Zachar’s view classifications are good if constituent categories are clinically useful; can be effectively linked to potential treatment modalities; can aid experimental research; cohere with basic science, like genetics, physiology, and psychology; and ultimately give rise to reliable diagnoses. In such a view, validity is a quality that needs to be demonstrated through clinical practice and research, not an inherent feature presumed to be at the basis of mental disorders, as is characteristic of the essentialist perspective.
Despite the scientific aspirations of the DSM-5, it seems that, at best, DSM disorders could be thought of as practical kinds. This means that laypeople and scientists alike should not simply assume that they are caused by biological disturbances. On the contrary, clear-cut biological disturbances prove to be related to only a few psychiatric disorders. Interestingly, while critical researchers have long pointed to problems with the pragmatic value of the DSM, biological researchers now draw attention to its limits as well. Hyman (2010), for example, indicates that the DSM categories don’t map with the biological structures underlying psychopathology and suggests that research designs formulated in terms of DSM categories hinder scientific progress. More recently, Thomas Insel (2013; Kapur et al. 2012), the director of the US NIMH when the DSM-5 was published, suggested that most diagnostic categories in the DSM don’t connect with underlying biological structures, hence his call for research that crosses DSM categories. Indeed, the RDoC project of the NIMH made such a step and studies biological structures and mental symptoms irrespective of the various disorder categories outlined in the DSM (Insel et al. 2010).
Apparently, the RDoC project continues to assume that mental disorders are natural kinds. Its exclusive focus on biological determinants of mental symptoms bears witness of this naturalistic attitude. However, the approach taken there leaves aside essentialist interpretations, and paves the way for more flexible natural kind accounts of mental disorders. An important example of a more flexible natural kind account can be found in the work of Kendler et al. (2011, p. 1146), who suggest that mental disorders might be seen as “mechanistic property clusters” (MPC). In their view, the practical kind approach is not sufficiently etiological or explanatory in nature. They believe that disorders are not merely pragmatic groupings of mental symptoms and suggest that there are “robust explanatory structures to be discovered underlying most psychiatric disorders” (Kendler et al. 2011, p. 1146). At the same time they don’t buy into the essentialist kind account: “The ‘kindness’ of species is not, from an MPC perspective, produced by a defining essence but rather from more or less stable patterns of complex interaction between behavior, environment and physiology that have arisen through development, evolution and interaction with an environment” (Kendler et al. 2011, pp. 1146—1147). In their view, psychiatric patients’ illness conditions reflect a limited number of mind/brain states, which basic research should discover. A similar account can be found in the work of Rachel Cooper (2005, 2007). In her view, mental disorders make up natural kinds since they have similar determining properties: “as the determining properties of members of a natural kind are similar, so long as environmental factors are kept constant, members of a natural kind end up being similar in many respects” (Cooper 2005, p. 51). She argues that mental disorders are natural kinds to the extent that they obey the same natural laws; disorders are not physical entities “present in the Garden of Eden,” but conditions that behave similarly in similar environments (Cooper 2005, p. 52).
What is key to these “natural kind” perspectives is that they all start from a philosophically realist and (post-)positivist perspective: human characteristics, like mental disorders, are empirical objects that must be studied with the experimental method of the natural sciences, which is thus valued as a superior method for gaining knowledge. What these explanations don’t take into account is the notion of the human being qua self-reflexive transcendental subject living in specific contexts. Indeed, mental disorders are not neutral objects, but mind/body states people actively manipulate through symbolic activity. Consequently, the study of psychopathology is partial when it neglects the way we relate to our mental reality. Moreover, people are not just plants living in an “environment”: they actively manipulate and create mental, social, and cultural contexts, and, moreover, generate meaning about them, which can change over time. Thus considered, Ian Hacking (2002) was correct when he wittily argued that mental disorders are above all human kinds: products of human activity that are directed toward control and social recognition. Diagnoses carry meaning—some are desirable, others not at all—and affect and change those who are classified. For example, based on disorder labels people create advocacy groups and construct identities, which contain do’s and don’ts for “true” specimens of that kind.
Therefore, instead of using static natural kind accounts of psychopathology we should perhaps consider psychopathology in terms of reflexive kinds. By holding on to the idea of “kinds,” we on the one hand suggest that, indeed, psychopathology may be governed by laws and structures that can be described in scientific terms, yet a proper study of psychopathology requires more than just a biomedical focus. On the other hand, these laws do not apply to the cases we meet in the clinic unequivocally. Indeed, in clinical contexts we don’t meet disorders or kinds of psychopathology, but people in whose life mental health problems take shape, and who might be qualified as a case or not. As one studies specific cases, particularities as well as singularities will be discerned: next to general- izable characteristics, psychiatric problems always have context-specific and case-specific qualities. Indeed, the reflexive relation humans have to their own mind/body states implies that they cannot be wholly generalized across cases. This is not a problem, but it requires a casuistic approach to diagnosis that doesn’t merely determine which type of psychopathology applies to a given person. Diagnoses should also describe and document how and to what extent such a patterned way of functioning can be discerned. Next to that, diagnosis should describe how psychopathology is related to idiosyncratic events and to the way in which the person deals with such events. In doing so, special attention should be paid to singularity, as discussed earlier in this chapter. From a Lacanian point of view this, above all, implies that the dimension of the subject and the individual’s way of being confronted with the Real should be taken into account. Indeed, contra the neo-Kraepelian doxa I believe that diagnosis is more than classification. It consists of mapping the regularities, irregularities, and deadlocks in a person’s functioning and of grasping contextual factors that determine the way in which a person tries to make sense of his own distress.
-  In psychology, different emotions, like happiness, sadness, anger and anxiety, are sometimes considered as natural kinds. However, whether this is justified or not remains an object of continuousdebate (Lindquist et al. 2013).