system
Given the following post, respond as if you're commenting on Reddit:
human
The nature of mental illness

I hope not to upset anyone with this question; I myself have been in both behavioural psychiatry and am currently undergoing psychoanalysis, so I don't wish to come across as unsympathetic to people with psychological struggles.

I am wondering what has been said to the idea that mental illness isn't a particularly functional category; that is to say, because there is no determinable "norm" of psychological state, there is no way to determine someone as being in a problematic state based on their deviation from such a norm.

Rather than labelling some people as "mentally ill", which our society seems far too eager to do (e.g. in cases of terrorism), wouldn't it be better to actually look at people's issues on a case-by-case basis, without having to put them in some normative (or, rather, non-normative) category? 

Thanks, I hope my question made sense.
gpt
Perhaps you'd like to check out M. Foucault's *Madness and Civilization* and the critiques thereof - it's one of the bigger analyses concerning how the concepts of folly/ madness/ mental illness were placed in relation to moral ideals and institutional order in historical periods from the Renaissance to the modern  times. Foucault's point would be that the category *is* functional, only not in the field it's supposed to affect directly - he perceives it as one of the categories that help actively create and categorize social identities and models of behaviour rather than describe any psychological states. The book seems to polarize its critics, but it's a must-read if you're interested in social foundations of the common, normalized perception of mental illness.