In many respects the field of psychiatry can be considered a pseudo-science. It has the linguistic trappings of science. Just take a look at the new DSM and some of the newly added disorders. Rather than this being a "society" classifying what is or isn't normal, I'd suggest you have certain bureaucratic institutional perpetuating their particular profession and field...The more disorders, the more psychiatrists are needed and with vague or general presets..They guaruntee their service.
For instance Oppositional Defiant Disorder is defined as “ongoing pattern of disobedient, hostile and defiant behavior,” symptoms include questioning authority, negativity, defiance, argumentativeness, and being easily annoyed.
Why assume society is automatically right? There are so many historical examples of society being wrong. The person could be disobedient, question authority, and be defiant and they could be right. But psychiatry takes the label "mental illness" and gets us not to listen to the person who in all likelihood is a kid and people are less inclined to listen to kids already.
While the idea of "mental illness" has some utility and I'm not saying that for instance schizophrenia shouldn't be considered a mental illness we need to stop and think.
Psychologists, scientists who study the mind and neurologists scientists who study the brain may be able to find correlations suggesting X reasons for Y psychological and cognitive phenomenon. HOWEVER, anytime they label something as either a "deficit", "disorder" or on the flip side label something as "adapative" or "good" (which happens far less often, they seem rather obsessed with only studying phenomenon they consider negative) they are inescapably pushing their own opinion of what is "Good" and what is "bad" into the label.
Why not a neutral psychology? Which categorizes things about the mind and about the brain and finds relationships between this or that having to do with the mind or the brain BUT which refrains from any sort of value judgment, refrains from saying "This is illness" and "this is good"?
It is not a scientist's job to determine what is right and what is wrong. Society, of course must decide that some behavior is right and wrong but that's not a scientific thing.
Accordingly for things like psychosis there should be treatment but we shouldn't pretend that it was science that told us psychosis was "bad" or "illness". Even in that case it is a societal judgment of how the mind or the brain should work.
Being consciously aware that these are societal judgments we would be less willing to push people around and tell them how they ought to think. I think even in the cases like psychosis treatment shouldn't be forced. Incarceration should be forced if the person can be demonstrated to be a threat to other people, but if they just want to sit in their cell that should be their choice.