What is Dia-gnosis in Psychiatry?


Knowing the difference between one condition and another is critical, even when the precise diagnosis is unclear.




“An agnostic is someone who doesn’t know, and di- is a Greek prefix meaning ‘two.’ So ‘diagnostic’ means someone who doesn’t know twice as much as an agnostic doesn’t know.”

–Walt Kelly, Pogo1

Pogo’s quip aside, the etymology of the term diagnosis is critical to understanding what psychiatrists actually do, as contrasted with what some critics mistakenly believe we do. The term means, literally, “knowing the difference between” (dia, across or between; gnosis, knowledge or knowing). When first meeting the patient, the psychiatrist’s primary task is to differentiate between the patient’s condition and many broad types of human experience. For example, is the patient experiencing an existential crisis, or a psychotic break? Normal, stress-related confusion, or an incipient dementia? Diagnosis itself has little to do with any particular classification scheme, such as the many iterations of the DSM.

Indeed, in my experience—and contrary to the canard that the DSM is "Psychiatry's Bible”—most psychiatrists do not adhere religiously to any particular diagnostic system. Rather, we make use of the patient's symptoms and signs in a holistic, gestalt manner to arrive, initially, at a general type of human experience. Many psychiatrists intuitively use a form of prototype matching to make the first rough diagnostic cut.2

For example, let’s say we are meeting with “Mr Alex,” a 19-year-old college student who presents with command auditory hallucinations to harm himself; the belief that “Satanic agents” have implanted a listening device in his brain; and a 6-month history of social withdrawal, academic failure, and severely blunted affect. Without picking up a copy of the DSM-5, virtually all psychiatrists will recognize the prototype of a psychotic disturbance, etiology unknown. Although we might strongly suspect schizophrenia—itself a heterogeneous illness—we keep open the possibility of some undetected medical or neurological process, a psychotic-level mood disorder, or a substance-induced psychosis.

By their very nature, prototypes are characterized by vague and fuzzy boundaries that overlap with neighboring prototypes. Yes, this is also true of many DSM categories. These features often prompt harsh criticism of psychiatric diagnosis. Yet there is nothing wrong or unscientific about this fuzziness, nor does it negate the painful reality of the patient’s affliction. As the philosopher Ludwig Wittgenstein once noted, a fuzzy beam of light is just as real as a sharply focused one.3

Having arrived at a rough, prototypical notion of the Mr Alex’s illness, we then try as best we can to refine our initial diagnosis by means of various ancillary tests or procedures; for example, laboratory testing to rule out an endocrinopathy; imaging studies to rule out a brain tumor; and in some cases, neuropsychological or projective testing to assess pathological personality traits. In many instances, we consult family members or obtain school reports to confirm our initial diagnostic impression. We often find that our initial diagnostic impression was wrong or incomplete.

The DSM Requires a Case Formulation

Seasoned psychiatrists have long recognized that the DSM diagnostic categories are only rough-and-ready guides to diagnosis, and not the alpha and omega of understanding the patient's problems. For example, we may sometimes view the patient’s situation in existential or spiritual terms, as when someone is going through the “dark night of the soul”—a concept you will not find in any DSM classification.4 Sometimes we recognize a culturally-determined reaction that is not at all pathological within the patient’s culture or ethnic group. Sometimes we recognize the patient’s condition as a normal adaptation to a recent stressor, and not a psychiatric illness at all. But to be clear: all of this falls under the rubric of diagnosis. We are inevitably differentiating between and among a plethora of possibilities.

Accordingly, much depends on the case formulation, which—contrary to a common misunderstanding—is actually required by the DSM-5 before an official diagnosis can be reached. Merely tallying up signs and symptoms does not a DSM diagnosis make. As the DSM-5 stipulates5,6:

“The case formulation for any given patient must involve a careful clinical history and concise summary of the social, psychological and biological factors that may have contributed to developing a given mental disorder. Hence, it is not sufficient to simply check off the symptoms of the diagnostic criteria to make a mental disorder diagnosis (emphasis added).”

Symptoms, Disease and Diagnostic Uncertainty

My colleague, Nassir Ghaemi, MD, has rightly emphasized the importance of diagnosing and treating underlying disease processes, and not merely throwing various treatments at a motley collection of symptoms.7 Without a doubt, identifying the underlying pathophysiology of the patient’s presenting illness (if illness it be) is the gold standard of all medical practice. But there is a serious impediment to achieving this ideal when it comes to real-world medical care.

Often, in psychiatry, we do not arrive at a specific and certain disease entity as the driving factor in the patient's presenting complaints. This is also true in much of general and family practice. As family physician Kirsti Malterud, MD, PhD has noted, it is rare, in family practice, that the physician can link specific observable signs to a specific localized lesion or pathological process. On the contrary,8

“…a clear and clean linearity between clinical phenomena, the names we can give them, and a subsequent rational treatment is the atypical exception rather than the norm in clinical medicine…The professional norm that objective signs are supposed to confirm subjective symptoms and thereby reveal monocausal disease processes falls apart in the sea of medical complexities encountered by the family physician.”

Nevertheless, Dr Malterud notes,8

"...the solution of the patient’s problem can often be achieved despite the impossibility of reaching an established medical diagnosis. The uncertainty demands that the physician is able to put up with provisional conclusions."

Often, in both family practice and psychiatry, physicians must do their best to alleviate the patient’s suffering and incapacity—the hallmarks of disease9—without knowing the precise, pathophysiological basis of the problem. Symptomatic relief is almost always welcomed by the patient, and constitutes a vital part of our medical and ethical responsibilities—indeed, of our very raison d'être as a caring profession. It need hardly be stressed that when treatment is mainly symptomatic rather than curative, the physician must exercise the utmost care and caution, avoiding remedies that might make the condition worse or expose the patient to undue risk. Of course, this is true even when we know the precise disease process and its pathophysiology—only more so when treatment is essentially symptomatic. Yes, our symptomatic remedies must always be based on the best available scientific evidence. But often, physicians must make critical treatment decisions in the absence of randomized, double-blind, placebo-controlled studies. In short, we must do the best we can.

The Necessity of Psychiatric Diagnosis

In a recent posting, my colleague Awais Aftab, MD, took on some of psychiatry’s most vocal critics—those “…who have been arguing for abandoning psychiatric diagnosis” altogether, and who “delight in making a mockery of diagnostic manuals.” Dr Aftab rightly responds that, “Such critics reveal their impoverished understanding of the nature of psychiatric diagnosis…”10 Indeed they do. Dr Aftab’s full commentary is well-worth reading.

Ultimately, abandoning diagnosis is clinically unworkable and ethically irresponsible. It amounts to carelessness, not care. It empties the House of Medicine of all wisdom and turns it into a shambles. At the same time, we physicians must be willing to live with a degree of uncertainty in our diagnostic quest, while always aiming to relieve the patient’s suffering and incapacity as safely and effectively as we can.

Dr Pies is Professor Emeritus of Psychiatry and Lecturer on Bioethics and Humanities, SUNY Upstate Medical University; Clinical Professor of Psychiatry Emeritus, Tufts University School of Medicine; and Editor in Chief Emeritus of Psychiatric Times (2007-2010). Dr Pies is the author of several books. A collection of his works can be found on Amazon.

For Further Reading
Ruffalo ML, Pies RW. What is meant by a psychiatric diagnosis? Psychology Today. June 7, 2020.


1. Dutch S. What's an agnostic? July 26, 2005. Accessed January 9, 2024. https://stevedutch.net/pseudosc/agnostic.htm

2. Phillips J, Frances A, Cerullo, MA, et al. The six most essential questions in psychiatric diagnosis: a pluralogue part 3: issues of utility and alternative approaches in psychiatric diagnosis. Philos Ethics Humanit Med. 2012;7:9.

3. Wittgenstein L. The Blue and Brown Books. Harper Torchbooks; 1965.

4. Pies RW. Psychiatry and the dark night of the soul. Psychiatric Times. December 14, 2020. https://www.psychiatrictimes.com/view/psychiatry-dark-night-soul

5. Diagnostic and Statistical Manuel of Mental Disorders, 5th edition. American Psychiatric Association; 2013:19.

6. Pies RW. Poor DSM-5—so misunderstood! Psychiatric Times. March 23, 2021. https://www.psychiatrictimes.com/view/poor-dsm5-so-misunderstood

7. Ghaemi SN. Symptomatic versus disease-modifying effects of psychiatric drugs. Acta Psychiatr Scand. 2022;146(3):251-257.

8. Malterud K. Diagnosis—A tool for rational action? A critical view from family medicine. Atrium. 2013:26-35.

9. Pies RW. What should count as a mental disorder in DSM-5? Psychiatric Times. April 14, 2009. https://www.psychiatrictimes.com/view/what-should-count-mental-disorder-dsm-v

10. Aftab A. Are critiques of DSM/ICD as devastating for psychiatric diagnosis as some critics seem to think? Psychiatry at the Margins. https://www.psychiatrymargins.com/p/are-critiques-of-dsmicd-as-devastating?utm_campaign=reaction&utm_medium=email&utm_source=substack&utm_content=postAAftab

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