Psychiatric nosology is currently under intense international scrutiny, both by the public and the professionals. Everybody is a stakeholder and everyone is speaking out, because it is a matter of their personal lives, more particularly of their private mental life. Everybody is also a stakeholder, because everybody has a mind and potentially everyone is a psychiatric patient. The right to liberty, right to expression and right to life empower them to assert their views. It is being questioned as to whether the recently published DSM-5 is a nosology of disorders, or just a list of labels of doubtful validity. Against this backdrop, the status of the psychiatric nosology needs to be examined dispassionately and objectively. Its limits, its strengths and weaknesses should be acknowledged explicitly to obviate undue criticism. A more fundamental analysis of the possible sources of this perpetual ambiguity in terms of the validity and applicability of the principles employed in formation of such nosologies is a matter of urgent concern.

Nosology has been defined as a branch of medicine that deals with classification of diseases.¹ Disease again is a medical concept, which signifies departure from health or the converse of health (Pearce 2011). As the concept of a particular disease evolves to ‘mature’ form, its symptoms get reliably defined and described. This is followed by delineation of its pathogenesis in terms of disruption of structure and function and, still later, its aetiology is determined. One of the first indicators of departure from health, at least to the primitive man, must have been the pain and suffering associated with the activities of daily life.

Sufferings of purely mental nature must also be equally old, because it is the mental dimension that truly defines the essence and uniqueness of man. Recorded medical history does bear testimony to this. Man is primarily and pre-eminently a mental organism. Evolution has allowed a massive quantum jump in his mental faculties. It is a paradox though that despite this massive enhancement of his cognitive abilities, he still appears condemned to remain a mystery unto himself. Actually, he is existentially structured to be so. This is so because mental dimension of man is not accessible to objective observation and analysis in the same way as his physical dimension is. It is not surprising, therefore, that the human race had to wait for several millennia, till the arrival of the ‘information age’, for such massive attention to get focused on the sufferings involving his mental dimension. Yet it appears to be just a prelude to the beginning. This is testified by the sudden emergence of many fierce and some pessimistic reactions to the just published DSM-5, with some calling it ‘a snap-shot of a field in flux,’ (Jabr 2012) while the National Institute of Mental Health (NIMH), USA, calling it at best a dictionary.²

Psychiatric nosology is to psychiatry what the soul is to individual human beings. Like the soul, nosology also continues to remain at the existential centre of psychiatry, but all the same continue to remain elusive and indefinable. The most fundamental issue surrounding psychiatric nosology is the issue of validity of its diagnostic categories.

Even though reliability has certainly improved tremendously through intensive international efforts, no progress has been made in the area of establishing validity. The search for validity is important, because that alone will separate real entities from pseudo-entities. Only real entities will be definite, definable and stable. Only real entities will permit predictability and be amenable to control. In fact, the validity issue has become further murky in modern times, because of the accumulation of an enormous amount of data from population and general hospital-based observations and studies. There is near universal applicability of ‘spectrum phenomena’ to almost all categories, a very high occurrence of co-existing or co-morbid diagnoses, and increasing necessity for use of not otherwise specified or not elsewhere classified categories (NOS/NEC) (Goldgerg 2010). Uncertainty about validity gets further highlighted by the frequent observation of diagnostic instability over time at the individual level, as well as by substantial changes made in the nature of categories and criteria, even by the international bodies in the subsequent editions of their classificatory systems. ‘Zone of rarity’ as a paradigm of separating different entities and defining their boundaries has not been supported by the observational data. The above mentioned observations are possibly because of extremely large number of factors operating simultaneously leading to enormous variability at the level of mental or behavioural phenomena. Very large number of factors lead to generation of innumerable, mostly unique ‘disposition-profiles’ of both normal and abnormal states, which defy classification as categories. Since it is not repetitive, it will not form a class and thereby would not permit classification. This raises a more fundamental question.

How valid and applicable is the notion that validity of psychiatric conditions can be established on the same parameters as that for other medical conditions? This notion is intrinsically flawed.

The intrinsic flaw is that we overlook the boundary between the physical and the mental when it comes to the issue of examining the validity of disorders in these two domains. We treat them both with the same yardstick. It would be a matter of common sense to presume that medical disorders would have features of physical domain, whereas psychiatric disorders would have features of mental domain. Physical and mental domains are qualitatively different. The physical domain is constituted of matter, whereas the constituents of mental domain are unknown. Properties of matter would apply to physical domain, but would not apply to mental domain. Therefore, the concept of validity as applicable to material domain would not be the same as that applicable to mental domain.

Inherent in the search for validity is the premise that the real has to be separated from the artefacts. The real is the one that exists ‘on its own’ in nature, whereas artefacts would be the subjective creations of human mind. It is something like the relationship between the waking experience and the dream experience. The physical or the material domain exists purely in the objective realm, whereas the mental domain exists exclusively in the subjective realm. It is not accessible to ‘objective’ observation. We cannot observe somebody else’s mind in the same way as we can observe his body and its different parts. As regards the mind, only subjective individual introspection is possible. Its existence beyond the immediate conscious experience remains unknown.

But, introspection is not considered a valid scientific method of observation, because it cannot be consensually validated through its agencies of observation. All the same, the validity of introspective truths cannot be denied; we have to focus our creative energies to devise paradigms for convergence of introspective and observational truths. Till the time we are able to do that, we have to make do with limited ‘validity’ for the psychiatric entities, commensurate with the primary dimension to which it refers to, that is the mind. In fact, international efforts should focus more on unravelling and establishing the nature of mind rather than its neurophysiologic correlates.

Modern age is dominated by doctrines of science. Science is dominating, because it has empowered people in their struggle against nature and has also transformed their lives. Science is a product of the human mind, but, unfortunately scientific methods are not applicable to the study of mental phenomena. Even most advanced neurophysiologic studies should not be equated with the study of mental phenomenon per se. At best, it can be a specific or a non-specific substrate for the other. The two cannot be considered interchangeably. Forcing a universal ‘brain’ explanation for all mental phenomena is like forcing a square into a circle. This is one of the reasons why such limited progress has been made in this area of brain–behaviour relationships, despite so much investment of resources of time, talent and treasure. Since psychiatry is a relatively recent offshoot of modern scientific medicine, it is still nurturing fond and nascent hopes, and aspirations of being similar to its brethren from the world of physical medicine. This natural-looking, seemingly acceptable goal appears completely oblivious of the fact that the physical and mental dimensions of man are completely and qualitatively different from each other. Even though they are seamlessly one and mutually interdependent, they are not on the same plane. They complement and supplement each other into emergence of a ‘supra-ordinary’ being, with some limited autonomy to impose certain rules of its own on itself and the milieu.

Some of the qualitative differences between the physical and mental domain has already been mentioned above. Further, it appears that even the concept of aetiology may not be uniformly applicable to both the mental and physical dimensions. Mental events and its manifestations are quite often dictated and guided by the goals or the end points to be achieved, which becomes obvious when we analyse our speech and behaviour. All our speech and behaviour is always guided by a goal. On the other hand, physical events are guided and dictated by the antecedent or the initiating influence. One is guided by the past, whereas the other seemingly is guided by the future as set from beforehand. This is a mystery as well as a paradox that both kinds of operating paradigms should not only co-exist within the same organism, but also should work seamlessly in consonance with each other. In fact, this should be considered as one of the most important attainments of the evolutionary process. Evolution is not simply about movement from amoeba to homo sapiens; it is as well a movement from antecedent driven causality to consequence driven causality, from ‘command’ driven causality to ‘demand’ or ‘goal’ driven causality. It is a very fundamental difference; therefore, different yardsticks become obligatory to be used for these two domains. In fact, it may be conceptualised that emergence of consciousness was necessitated to provide a transcendent plane where goals and directions could be preset for emergent behaviours to be expressed by organism. This would also make the behaviour of the organism predictable, and thus, setting the stage for collective living to form societies, civilizations and cultures.