I believe diagnosis is one of, if not, the most important parts of a doctor’s job. It’s actually the main goal of the entire medical undergraduate curriculum. However, we’ve limited what we mean by diagnosis. A diagnosis is not just the identification of pathology, it’s an understanding of a patient’s illness, a point which is all the more important when you consider patients with “co-morbidities” (more than one thing wrong).
In an interesting personal article in the BMJ Gordon Caldwell, a consultant physician working in acute medicine, says
The time taken to reach the correct diagnosis may be crucial for the patient’s chance of survival. Over my career I have seen many errors in the working diagnosis causing harm to patients and even death.
He also considers the importance of creating the right working environment for doctors to make good diagnoses
I believe that we have not thought about the best places, the physical and psychological environments, in which doctors should do this complex clinical thinking. Often it occurs in small hot rooms subject to constant interruption or even in ward corridors without easy access to laboratory results.
He concludes –
We must design our working spaces and information systems to maximise doctors’ ability to see, understand, and deliberate on the information needed for more precise diagnosis. We must allow clinicians enough time to be careful in diagnosis, treatment planning, and treatment review. We must urgently consider how to provide rooms, time, and information for doctors to do the most difficult part of their job and the part most prone to error: the clinical thinking in making the working diagnosis and treatment plan.
This is absolutely right. The scandal of the NHS is that we expect good health care to be provided without giving doctors adequate time with their patients to really understand them. We also frequently fail to provide good working environments and to share all the relevant information amongst the various members of the team.
Heroes Not Zombies 
According to Kent, diagnosis is not the test of the physician, but his ability to cure is. While diagnosis is important, as you rightly point out, it is not the definition of the pathological state, but the understanding of the needs of the patient. That need is the similimum and the effects of the remedy determine the outcome of the diagnosis. That outcome is the goal. I know homoeopaths – and the past has produced numerous of them – who can understand the essence of a case without any diagnosis. Lippe was a past-master at this and we can all learn from him. Von Boenninghausen was another who understood the essence of the case from but few parameters.
hmmm…don’t want to argue over precise definitions, but for me, diagnosis is the understanding of a patient and their condition. I just don’t think you can help anyone without this.
I also think that in itself it’s a “good thing” – it is incredibly powerfully healing to know that someone cares and understands.
I do think that’s the foundation of my job – to care, and, to understand. I wouldn’t want to practice medicine without either
I’m a huge advocate of a positive therapeutic alliance being beneficial to patients even before diagnosis is made (and even if it is never made).
But a diagnosis – even if it is just a working hypothesis – allows many more therapeutic avenues to open up.
It is sometimes possible to effect at least a partial cure without having a firm diagnosis, but the more information gathered, the clearer the picture of our patients that emerges, and the more therapeutic options manifest themselves both to us as clinicians, and to the patients themselves, from the process of diagnosis.
I like Dr Caldwell’s emphasis on a good working environment to make assessments. Perhaps I’m slightly biased since I’ve just got back home from an assessment and our team discussion had to take place (as it often does) in a hot, poorly-ventilated and cramped clinic room in a police station…
Certainly not an environment best suited to discussing complicated issues and thinking through the consequences of actions!