The caveat would be that there are some in the psychiatric survivor community who don't believe there is such a thing as "mental illness"--that unless you're talking about a specific injury to the brain, most if not all of what society commonly terms "mental illness" is actually a reaction to societal stresses--for instance, post traumatic stress disorder, which is a response to physical violence, or sexual abuse, which are social, not individual problems. They see the medicalization of "mental illness"--and the widespread use of psychiatric drugs--as a way to cover over issues like poverty, domestic violence, war, racism, sexism, homophobia, all of which cause individuals to respond in ways our society would rather label "mental illness"--as opposed to dealing with the root causes of these individual responses. For example, they would say that the widepread incidence of "depression" in our culture is a response to the various social ills we face over which individuals are trained to feel they have no control, and thus end up feeling disempowered and "depressed." Rather than drug the population, (and feed the coffers of the health care industry) they would say a better response would be for people to organize politically to address these issues, thus feeling more empowered, less "depressed."
One illustration of what I mean is how homosexuality used to be considered a form of "mental illness." It wasn't until the gay rights movement challenged the psychiatric establishment that this definition was changed. True, gay people in prior times (and now) were perhaps more likely to feel depressed, suicidal, etc.--but that was a response to the shitty way they were treated by society, not something inherent in being gay. Thomas Szasz wrote a book called "The Myth of Mental Illness" that lays out some of this, there's lots of other literature along the same lines.
This is not a consensus view, and there's quite a lot of diversity in the psychiatric survivor movement. Some people do believe in "mental illness" as an objective fact and not simply (!) a social construct. They still however advocate for more humane treatment of people labeled "mentally ill" and an end to stereotypes and bigotry that people with mental illness often face, which yes, is another form of "ableism."
Check out Judi Chamberlin's book "On Our Own" which talks about responses to "mental illness" that are community/peer based, as opposed to being delivered by the medical-pharmaceutical complex. Also, "The Madness Network News Reader" is a really good basic text on the psychiatric survivor movement. These are both kind of dated, but still good stuff. You can also go to the MindFreedom International website (easy to find on Google) for more info.
Sorry for the longwinded answer, but it's sort of a complicated question.
Best wishes.
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