Making a neurological diagnosis is, par excellence, the application of sloppy logic. Information from the patient and from tests is gathered and synthesized, some is discarded, and a label is applied. It is, of course, an imperfect process. As such, diagnoses can seem to merely reflect symptom clusters. However, as molecular investigations become more and more sophisticated, it has become clear that many, perhaps most, diagnoses reflect problems in specific biological processes.
Hardy J. Neurological Diagnoses Identify Molecular Processes. Arch Neurol. 2010;67(4):400-401. doi:10.1001/archneurol.2010.41