Why can't people have brief periods of mental illness for things such as anxiety and depression? Just because you got pneumonia once doesn't mean that you'll always have it. It just means that 'oh dang there was this one time when my lungs hated me'.
This dichotomy of how we think about 'mental' vs 'physical' illness still perplexes me. More than 25% of people have had a run in with gastro or the cold... we don't consider them somehow tainted because of it.
Imho, this reads more like a social/stigmatized view of the construct of mental illness, no?
It is
trivially true that our current nosological categories are socially constructed. I would strongly suggest you read a good history of the DSM creation process to get a sense of how utterly
contingent and
arbitrary the categories we work with today came to be. Many examples along the lines of "most people on the committee wanted things to be this way, Robert Spitzer didn't like it, so it was this way instead" or "no one really thought this was a good way to do this, but Donald Klein felt slighted, and so it was done that way after all." The DSM categories are not induced from empirical data; though there is a robust literature that
does attempt to induce diagnostic categories from comprehensive symptom surveys, it very rarely ends up inferring categories that clearly map onto the DSM!
A major problem with applying a medical model built around the paradigmatic case of infectious disease to problems of human cognition, emotion, and behavior is that none of the axiomatic bases that make that model work so well for, say, tuberculosis obtain. For almost no psychiatric disorders (or at least that are currently within the psychiatric wheelhouse) do we have a clear mechanism of disease, with a clear etiology, with a clear pattern of response to treatment that is
relatively specific to that disease process. Sure, trauma does seem to set people up for PTSD, but those same traumatic experiences can also raise the risk of bipolar I, schizophrenia, eating disorders, OCD, etc, and, inversely, all of those things can happen without any significant trauma history
whatsoever. Whereas you simply
cannot have TB without the presence of significant numbers of
mycoplasma tuberculosis somewhere in your body. ID people obviously consider risk factors all the time and these are very important in epidemiological research, but the fact that, say, being homeless puts you at higher risk of getting TB is not used as
part of the definition of TB. That is because the illness entity is defined
independently of the environmental factors that happen to accompany it given the social and economic conditions that exist in the world. We're not even close to this for the entities we work with.
(the observant will remark that this applies
mutatis mutandis to many chronic diseases that are controversially treated by FM/IM folks, such as T2DM, obesity, chronic MSK pain, etc; those who are even more observant will notice that these conditions are "managed" rather than "cured" and that there is a huge effort to teach PCPs to use techniques originating in psychotherapy to address these, and will perhaps allow me to pass over them in silence for now).
Instead, with the kinds of problems we deal with, we are essentially identifying patterns of beliefs, attitudes, behaviors, perceptual experiences, and cognitions and saying "these things are simply not a healthy part of the human experience and as a society we should definitely devote significant resources to eradicating them, because we said so." Yes, the DSM has their little caveat about distress or impairment, but this is so far from an objective standard as to be ludicrous on its face as a useful criterion for separating out What is Pathological from What is Merely Weird or Inconvenient. We rely on the moral weight of our pronouncements to label things as pathological or non-pathological, so I think it is incumbent upon us to apply a relatively conservative definition to what we are comfortable calling an illness and applying a medical model to. When you examine literature about the extent to which many non-symptom related factors determine who gets what kind of diagnosis (e.g. being black is an independent risk factor for being diagnosed with schizophrenia v. bipolar or psychotic depression), I think you are forced to this position if you are interested in intellectual integrity. A cursory examination of the history of Things We Thought Were Disorders in the Barbaric Past But We Are All Perfectly Enlightened Now supports this. I will not go into the history of homosexuality being in the DSM until shockingly recently, drapetomania, the original origin of the idea of "passive-aggression" etc.
That said, clearly there are patterns of symptoms and experiences that go together that are often associated with having a really profound impact on someone's life. Some of these patterns of symptoms are strongly heritable and are in large part attributable to genetic influences. And people have to live in reference to society in some way or another, so socially constructed ideas are definitely going to interact with these in meaningful ways! So there are some psychiatric entities in the world that are probably
Dingen an sich. It is this category of things that I take to be the class of mental illnesses per se.
Your gastro and cold examples are actually perfect. The symptoms involved are definitely real - people are not lying about their experience. They are caused by something, in this case one of approximately a billionty viruses. And they can certainly cause distress. But in 99% of cases,
these are not medical problems. You deal with them at home, drink lots of fluids, blow your nose a lot, maybe take a day off work, stock up on OTC remedies that have often never been compared systematically to placebo. Sure, there are some prescription agents that you might actually get some relief from, maybe/probably. There are clearly ways you can feel better. And they can set you up for developing uncontroversially medical problems. But I think it is not at all unreasonable to ask if we want to talk about these as disease states or illnesses v. "something that is obnoxious or distressing that happens to people sometimes."
The worry is that if you make 1 in 4 people pathological on very shaky grounds, you are attempting to abolish negatively valenced human experience, which, fine, if you want to be a hardcore utilitarian might be defensible, but is very different from anything I want to be a part of.