The passing of clean taxonomies.

Among the most productive constructs of the enlightenment are the modern taxonomies. These have been helpful in bringing order to the chaos of signs and symptoms and other clinical findings and were central tools in achieving our 20th century understanding of pathophysiology. They have also have an influential role to play in reimbursement for medical services. With the dawn of high-throughput molecular diagnostics many of us recognize that we are going to be able to be far more precise in our diagnostic and therefore therapeutic approach to diseases and their prevention.

Nonetheless, as we approach the systematization of medicine, we will be reminded often that nature may not hew to the simplified models that we are developing. This recent study in the New England Journal of Medicine, just does that by demonstrating directly that within a "single" tumor there exists a large multiplicity of tumor types, each with its own genomic characteristics and therefore particular therapeutic responsiveness (or lack of it). It can be argued that this is another instance of the tension between the "neats" and the "scruffies" but perhaps it is a foreshadowing of the decreased effectiveness of taxonomies as a cognitive tool for biomedical discovery and clinical care. If indeed, the underlying substructure of physiology is best represented by a probabilistic network model that can only be best grasped and managed through the use of computational tools, we have to seriously re-evaluate both our approach to disease definition and biomedical education.