Like Francesca above, I use the term “mental illness” (and other synonyms) out of convenience. A much better term to me is “problems in living” (a Szaszian phrase). Surely, the experiences exist. And in many cases those experiences are problematic, either for the person himself or those around him. But “mental illness” is a metaphor; the mind is not an organ and thus cannot be diseased. There is no inherent harm in using metaphors to describe human suffering except for the risk that some people take the metaphors literally.