Known Unknowns: The Difference Between Science and Scientism in Psychiatry

Ronald W. Pies, MD


May 05, 2016

In This Article

Scientism, Not Science

The objection that psychiatric diagnoses are not "scientific" because they are not grounded in clear-cut biological findings represents a misunderstanding of the scientific process. Indeed, of the five original criteria for determining validity put forward by Robins and Guze, only one was specifically biological.[4] The five phases proposed to achieve valid classification of mental disorders were clinical description, laboratory study, exclusion of other disorders, follow-up studies, and family studies.[4,5]

As Dr Bernard Carroll has pointed out, "The existence of a medical disorder is not predicated on having a laboratory test for it" (Personal communication, 11April 2016). After all, what is the imaging study or laboratory test for validating migraine headaches or atypical facial pain?

Dr Carroll elaborated on this crucial point in a recent publication[6]:

...biomarkers are not an automatic gold standard of evidence for diagnostic validity. Indeed, thoughtless diagnostic testing can cause mischief through unnecessary further testing and treatments. Laboratory measures are the servants of clinical science, not the other way around, because most diagnostic tests are probabilistic rather than pathognomonic—so clinical judgment enters into their selection and their interpretation.

Indeed, the insistence on lab tests or other biological criteria for the scientific diagnosis of disease is not science, but rather "scientism," defined by Merriam-Webster as"an exaggerated trust in the efficacy of the methods of natural science applied to all areas of investigation (as in philosophy, the social sciences, and the humanities)."[7] Psychiatry, after all, is not a "natural science" in the sense that anatomy and biochemistry are. As Dr Jose de Leon has stated, psychiatry is instead "a hybrid scientific discipline that should combine the methods of the natural sciences (defined as the empirical sciences which study the natural world) and the social sciences. These sciences provide, respectively, an explanation of illness that follows the medical model and an understanding of psychiatric abnormalities that are variations of human living."[8]

Furthermore, a purely biological explanation of a psychiatric problem—even if correct—does not necessarily mean that a biological approach to treatment will be the most effective. Suppose we were able to identify a specific neurocircuit that was causally related to post-traumatic stress disorder. It would not follow that a biological intervention, such as a medication, would be superior to some form of trauma-specific psychotherapy. Moreover, the whole notion that we should separate "biological" from "psychological" treatments* can be challenged on both philosophical and clinical grounds, as Dr Glen Gabbard has forcefully argued.[9]

With that being said, we should not succumb to the myth that psychiatry has no biological basis at all. Although "office-ready" biomarkers of psychiatric illness are probably years away, there is growing evidence that schizophrenia, melancholic major depression, obsessive-compulsive disorder, and bipolar disorder (among others) are associated with specific biological abnormalities. As Calkins and Iacono[10] noted, "the occurrence of ocular motor dysfunction in schizophrenia patients and their first-degree biological relatives is remarkably consistent." Meanwhile, on the clinical level, a recent meta-analysis by Leucht and colleagues[11] found that psychiatric medication is roughly as effective as medications used in general medicine.