^ I see what you mean. I was going for the strict medical definition of "symptom" there but I like your ranking of primary, secondary and tertiary. To my mind though - heart disease is usually secondary to many things - eating unhealthily, diabetes, smoking, high blood pressure, but it is still a disease. If you go further back, eating habits and smoking (and diabetes which can be caused by eating habits) could have an array of primary causes - stressful life, how you grew up, other external influences..
Or take depression again - I think that it often arises when external influences, shitty life, traumatic event, stress, particular personality traits, whatever it is coincides with abnormal brain chemistry. Or maybe the external events
cause the abnormal brain chemistry. That doesn't really matter in my eyes.. anyway, external factors are very important but it's still an illness. Hmmm though I suppose you certainly can have depression with no obvious external cause, where as addiction is unlikely to progress to, well, full blown addiction without the external factors being prominent.
I guess what clinches it for me in terms of disease is the fact that addiction causes actual changes in the brain which differentiate it from a non-addicted brain, and has an impairment to functioning that goes alongside it. That to me says disease/illness, whatever the primary cause (and I agree it is very multifactorial, and doesn't start as an illness at all, that def comes later). But you know what, I think actually we're all agreeing here, it's just a question of the words and we're using being a little different
