One of the things that frequently occurs in debates over various alternative sexualities and sexual identities is the cry that, “Such-and-such isn’t in, or was removed from, the DSM!” or “The DSM says….” The DSM is short for the Diagnostic and Statistical Manual of Mental Disorders. This document is important because it defines how psychiatric professionals are supposed to diagnose and treat various mental illnesses. Two important examples of this are the removal of homosexuality from the second edition in 1973, and the shift in 2013 from Gender Identity Disorder to Gender Dysphoria (Transgender), which represented a shift in focus from gender identity to distress over the physical gender.
The idea is that the DSM represents the state-of-the-art understanding of all things mental illness, and that anything in it represents Truth (note the capital T). The conclusion, then, is that anything not listed in it is not a form of mental illness. Moreover, for anything that is listed as a mental illness, it contains the full and authoritative list of treatments. In other words, citing the DSM is an Appeal to Authority. While it is a very reliable authority, it is not infallible, as evidenced by the fact that it changes periodically.
As mentioned above, the DSM changes periodically. It’s currently on its fifth major revision, with several minor ones as well. This means any change that has been made to the DSM can be reversed. Since changes to the DSM are basically decided by a committee, that means that a concerted effort to get Christians into the field of psychology, for example, could result in homosexuality being added back to the DSM, or maybe even adding atheism!
The more fundamental issue, however, is that citing the DSM dodges the more fundamental question of “What is a mental illness?” Merriam-Webster defines it as:
Any of a broad range of medical conditions (such as major depression, schizophrenia, obsessive compulsive disorder, or panic disorder) that are marked primarily by sufficient disorganization of personality, mind, or emotions to impair normal psychological functioning and cause marked distress or disability and that are typically associated with a disruption in normal thinking, feeling, mood, behavior, interpersonal interactions, or daily functioning.
This means a wide variety of things can be a mental illness, even if they don’t have a specific diagnosis listed in the DSM. Also, notice that it is, in particular, a “disruption in normal [things]”.
“Normal” is a fairly subjective term.
Citing the DSM has relevance, since it is an authoritative publication. It’s a product of humans, however. It is written by people with an incomplete understanding of the human mind. It is written by a committee of such people who work in what is sometimes called a “soft science.” Soft science is a science where it’s very hard to determine what is fact and what is just highly likely. Moreover, it’s an area where politics can come into play. With the large number of groups and money involved in mental illness today, to ignore the possibility of undue influence is unwise.
Further, when discussing mental illness, what’s important is the simple fact of an existing disruption of normal processes within the mind. The belief that Friday the 13th is an unlucky day is a superstition. To have mild anxiety over the day isn’t really a mental illness, but if it’s a bit extreme it could get you laughed at. To hide in your bedroom every Friday the 13th with the lights out would certainly rise to the level of mental illness, even if it only affects you a couple times a year. At some point you have an anxiety disorder. Or a phobia. Or something. The exact diagnosis doesn’t really matter for this illustration. What matters is your life is impacted by something that is chewing up your vacation days on a regular basis over something that’s pretty silly.
When talking about homosexuality, noting that it’s no longer in the DSM doesn’t address the question of whether being homosexual impacts a person’s emotions (in particular) to such a degree that it disrupts normal (whatever that means) feelings, behaviors, and interpersonal interactions (among potentially other things). When dealing with gender dysphoria (aka, transgenderism), the DSM has a diagnosis, but there’s a lot of disagreement about what is appropriate treatment.
In the end, the DSM is only part of a discussion about mental illness. Citing it with no further explanation represents an appeal to authority, which can rightly lead to discussions about the credibility of the document. Unfortunately, the people who are citing or critiquing it are often not in a good position to assess its credibility, or even accurately state its objectives.
Taking into account the nature of the manual (chiefly being to help psychiatric professionals consistently diagnose the same people with the same mental illness, and a not an authoritative list of mental illnesses) is critical to any discussion that involves the DSM. The DSM is not the be-all and end-all. Treating it as such is dishonest.