I am thoroughly confused about people's feelings around diagnosis. The DSM is widely disliked and mistrusted, and for very good reasons, but that dislike and mistrust extends beyond the DSM itself, infecting words and concepts in the vicinity and undermining the foundations of our discussions. We are encouraged to think there is a fight going on, with "diagnosis" in one corner and "psychological understanding" in the other. In my head this all starts to unravel when the meaning of diagnosis is brought into play. A conversation begins with a call to abolish psychiatric diagnosis. Later in the same conversation it is said that the problem with the DSM is that its classifications are not sufficiently similar to a diagnosis. Confused? You ought to be.
Another brick in the wall...or another drop in the ocean?
Allow for sake of argument that our knowledge of psychological causes and processes is excellent, far better than it is now. Imagine when are confronted with an experience like paranoia or depression that we can take a life history and determine with a high degree of accuracy what are the importance of various factors in it's aetiology ("you started to feel different when you were bullied at school; it made you withdrawn and quiet. Later in life this changed how people responded to you and you began to feel they didn't like you either, making you feel more depressed and more anxious") With this superior knowledge might we not start to notice that people with different sorts of problem would respond differently to different sorts of help? What we would have would be a way of knowing the nature of aetiology, the processes it fed into and how they became the presentation we see before us. Would not such knowledge equate to a diagnosis (in any widely accepted sense of the term)?
Now perhaps we would be reluctant to call it a diagnosis. "Diagnosis" we might reason "sounds too much like something a doctor does. We aren't doctors, we want to think of different ways of helping". This may or may not be a sensible decision to make, but that is beside the point, it is a decision, and an aesthetic one at that. If we don't like the word "diagnosis" then we don't like it. I don't like the word "treacle" but if someone shows me a jar of something sweet, brown and viscous, I may have to concede at least its accuracy. So too with diagnosis. There are many reasons to feel funny about the DSM, one of them is that it fails to do what a diagnosis ought to, but isn't it rather strange then to simultaneously abhor the DSM and to abhor the thing it is failing to be?