Jason had an idea to do a mini carnival of neuro-type and psych-type bloggers on this, and I though it would be cool, though admittedly right now I'm so swamped for topics I hardly needed another one!
But here's Sci's Take.
To start out with. Psychopathology is a word I never use. Never. In fact I didn't even know it existed until I got Jason's email. Obviously I knew immediately what it meant, but scientists in my field basically don't use terms like "psychpathology". To be honest, we don't even use the term "mental illness" all that much. Usually, we are a LOT more specific, referring specifically to ADHD, major depressive disorder, anxiety, PTSD, schizophrenia, etc. In addition, psychopathology refers often to the studies of BEHAVIORS associated with mental disorders. While we do study behavior, we don't tend to do it so much in humans.
And I have to say I like our specific natures in this regard. While I don't doubt that psychopathology is a useful term when used in terms of maladaptive behaviors...I'm not sure it's the best one. The reason I'm not sure is that, to me, psychopathology kind of sends off little blips of mind/brain dualism. Psychopathology refers to behaviors and problems in the MIND. To the public, the mind is still distinct from the brain, and that's why I worry about this dualism. The mind and the brain are NOT distinct. Every behavioral manifestation has an underlying biological basis, and biological states are affected and changed by your environment and your own behaviors (mind/brain blowing, yes?). So I feel like, to continue using the term "psychopathology", is to continue to perpetuate, at least to some extent, the idea that the mind and your behaviors are somehow separate from the rest of you.
And of course, if you feel your behaviors and your mind are separate from your biology, it becomes that much easier to tell someone it's "all in your head" (well, it IS, but not like you'd think), and that you just "need to have more willpower/work harder/try harder/smile/make friends". And we can all agree that that is not productive, and merely serves to condescend to the patient and belittle their very real suffering.
So me? I'm more in favor of "mental illness", "mental disorder", and other terms which speak to the underlying biology. It makes the presence of the illness real, and while it allows for the study of behavior (which is an incredibly important area of this research, you cannot know if you have success in biology until you see a corresponding change in behavior), it also makes clear the the fact of physical changes in the brain which are associated with it. And this allows us, as scientists and in the clinic, to attack the illness from two angles, changes in behavior AND changes in biology. And the more angles we have, the greater our probability of success.