I would say that both sides of the argument that VladRussian started have a point but equally lack civility: viggity simply linked to a suicide prevention site and VladRussian lashed out how somebody dare to ask for suicidal people to seek help when it's society at fault. Cushman took offense and implied that depression is the culprit here. Cue further misunderstanding about the wording of "imaginary".
I think both sides are projecting their own view a little too hard on this.
Environmental factors surely are a factor in this and I was 'quoting numbers' because VladRussian was a little to quick to dismiss mental illness. Again - since we all don't know the details in this particular case, this is an abstract discussion about suicide. In an abstract discussion, you either make a case and discuss it, or you discuss one that another person has made. VladRussian simply picked a fight and Cushman bought into it.
Also, re: circular logic. I don't think it is circular - Suicidal thoughts may be a symptom of depression, but that's not the same as saying they are a cause of depression. I know you don't say that either, but that's what would make it circular. (Also: saying it's 'somewhat circular' is a cop-out - it either is, or isn't circular.) I further don't think mental disorders really are "blamed" for suicide, they are simply accepted as a very common pathway in medical studies.