Nobody likes people who say "I'm right and you're not." We've all learned to be diplomatic, so nobody's feelings get hurt. Even when we're completely certain we're right, we realize it's good manners to say, "I'm sure there are ways you're right, too," or, "No doubt we both have something useful to contribute to this."
But science is different. The scientific enterprise is about getting closer to the truth, by discovering or creating new understandings, and discarding older ones that we know are misguided. In science, we cannot patiently accommodate mistaken ideas because it's good manners. Some people may still believe that the Earth is flat. Yet it would be very bad science to say, "Hey, no problem. We're can both be right! Let's make a theory that the earth is round and also sometimes flat. Everyone will be happy."
Somehow in the field of addiction, "making nice" has managed to grab a powerful foothold. Ask nearly any psychiatrist about the nature of addiction, and she is likely to support the notion that it is a "biopsychosocial" phenomenon. This word, invented in the late 1970's, was intended to act as a sort of tepid catch-all which included every possible factor in the development of addiction: biological, psychological and social. Everyone's model got a seat at the table. Today the "biopsychosocial" explanation has become standard for virtually every psychiatric problem. And why shouldn't it be popular? "Biopsychosocial" may be the most diplomatic medical term ever invented.
Biology, sociology, and psychology represent three separate pathways to understanding behavior, which may or may not overlap. If a woman is exposed to rabies, she may begin acting aggressively and erratically, a pattern of behavior that is the result of purely biological factors: she is infected. If a man lacks food and shelter, he will be more inclined to break the law to get what he needs to survive, a pattern of behavior that is psychosocial. And if a person responds to feeling overwhelmingly helpless by drinking or gambling or overeating, this pattern of behavior is psychological.
The lines get blurred sometimes in the study of addiction because these contextual factors may appear together. If an impoverished man becomes an alcoholic, certainly his social state is a factor. But his solution to this particular helplessness is a psychological symptom. Poverty contributes to addiction, but it is not the deepest understanding of it.
Speaking personally rather than scientifically, I wish I could make friends with everyone and add in biological and social factors to the basic nature of addiction. I happen to love biology: I was a biology major in college and did my honors thesis in embryology. In medical school, my favorite of the basic sciences was Histology: deciphering microscopic slides of different tissues.
But science isn't about what you love, or about being nice. Sadly, the "biopsychosocial" idea is doing more good for theorists than for addicts.