In my ‘online’ textbook of ‘rashes’ (ed.derm.101), that is the non-cancer bits of dermatology, I have a chapter called ragbag. I used to have two ragbag chapters, but now by combining them, the subject has been made simpler and easier, even though the content is unchanged. I am sure students agree. I put in this chapter all the things I do not put elsewhere. I thought I should now fess up a little, as Gödel would not have said.
In ‘John Wilkins’ Analytical Language’, Borges refers to the work of Franz Kuhn and his work on the the Chinese encyclopaedia the ‘Heavenly Emporium of Benevolent Knowledge’ (John Luis Borges, Selected Non-fiction, ISBN978-0-14-029011-0). This work is a classification of the world. For instance, you can classify the world into various groupings or categories. For animals we have:
- Those that belong to the emperor
- Embalmed ones
- Those that are trained
- Sucking pigs
- Fabulous ones
- Stray dogs
- Those that are included in this classification
- Those that tremble as if they were mad
- Innumerable ones
- Those drawn with a very fine camel hair brush
- Et cetera
- Those that have just broken the flower vase
- Those that, at a distance, resemble flies
All very straightforward stuff, as any medical student will agree. I also like the system proposed by the Bibliographical Institute of Brussels (after Borges). It parcelled the universe into 1000 subdivisions with number 262 corresponding to the Pope, 268 to Sunday Schools, 298 to Mormonism, and 179 to cruelty to animals, duelling and suicide.
We have lots of similar systems in medicine, some of which seem less fit for purpose than those described above. My incomplete categorisation of categorisation (the grant was turned down) is as follows:
- A minority are generative — you get more out than you put in. We work hard to avoid these.
- Some are overtly vexatious.
- Soem are covertly vexatious.
- Some require more input that you get out (like fees).
- Some require so much learning to understand the nuances of the classification, that learning the ‘facts’ is a relief.
- Some reflect career enhancement on the part of the teacher.
- Some are designed to allow a subject to be examined in a MCQ.
- None of the above.
- All of the above.
Dreyfus and Dreyfus, the US philosophers and students of AI, pointed out that although we like to use rule-based systems in teaching, experts quickly forget them, and do not appear to use them (From Socrates to Expert Systems:The Limits of Calculative Rationality, 1984). We just inflict them on the young either because that is the only way we know how to encourage learning, or because we repeat what happened to us earlier in our career without good reason. Quoting Dreyfus and Dreyfus:
The beginning student wants to do a good job, but lacking any coherent sense of the overall task, he judges his performance mainly by how well he follows his learned rules. After he has acquired more than just a few rules, so much concentration is required that his capacity to talk or listen to advice is severely limited.
They were not writing about medical students. But I recognise what is going on. I can remember it too. Classifications may or may not be useful in learning a subject, and in chunking, may provide a guide to action. But the more experience you get, the less the clinician uses them. Academics, of course, play by different rules, and get to write the rules.