What's good about subjects – and what's bad about them

The world is a complex, messy and interconnected place.

Human brains are powerful, but they can struggle to deal with all this complexity. Perhaps the biggest limitation our brains place on our ability to handle complex problems is our working memory. Our working memory is limited to just 4-7 items of information at any one time. Any more than that and we are easily overwhelmed. Think of that feeling you get when you are asked to memorise a 10 digit phone number in a few seconds. That’s cognitive overload! And that is always the risk when you learn anything new, or are confronted with any new problem.

However, human beings as a species are capable of engaging with and even solving some pretty complex problems. Cars, buildings, books, symphonies, product launches – these are all significant intellectual feats that require humans to manage more than just a few items of information. Given the limitations of working memory, how are we able to perform such complex feats?

The answer is that we cheat the limitations of working memory by committing facts to long term memory. Think of the difference between an adult and a child reading a story out loud. Stored in the adult’s long-term memory are the sounds that each letter makes, the meaning of all the words and the pattern of typical stories. The child’s knowledge of these things is much more fragile. They are much more likely to have their limited working memory overwhelmed by trying to de-code what sound the words should make, leaving little space left to think about meaning. This process isn’t just true of reading, it is true of all expertise. Research on chess players, physicists and concert musicians shows that experts have powerful mental schemas consisting of thousands of well-organised facts stored securely in long-term memory.

Traditional school subjects divide up the complexity of the world into small chunks that our limited working memories can handle. We don’t ask five-year-olds to wrestle with real-world problems – we get them to learn the sound that the squiggle ‘a’ makes! Focussing on these smaller steps is much less overwhelming, and also lets us build up the mental schemas we need in long-term memory to be able to cheat the limitations of working memory in the future.

In short, subjects are powerful cultural inventions that offer an efficient way for both societies and individuals to preserve and hand on important knowledge.

But are they the best way of organising all university study? The ultimate aim of acquiring these powerful mental schemas is to use them to solve real-world problems. As students get older and begin to develop their expertise, we need to think about the right way of introducing these real-world problems. If we stay with the traditional division of subjects for too long, problems can creep in.

First, it’s noticeable that many modern scientific breakthroughs occur at the boundaries of subjects. This may well be because the artificial subject divisions have encouraged people to stay within the subject, meaning that the boundaries between the subjects are relatively under-explored, and ripe for investigation. In the early 20^th century, research at the boundary of chemistry and physics led to huge advances; in the mid-20^th century, cracking the code of DNA required blurring the boundaries of chemistry and biology, and today, organisations like the Santa Fe institute attempt to find patterns and order in very different complex systems.

Second, the problems we face in the world today often require insights from many different fields. Experts need to work in teams with other experts, and to develop some understanding of how these other fields affect theirs.  For example, in the last few decades, economics and many areas of public policy have been changed by insights from psychology about how people make decisions. Today, the increased availability of large data-sets is transforming the way many disciplines work.

Sticking unthinkingly with traditional subject boundaries risks creating experts who are isolated from the real world and unable to respond to the changes in other disciplines. Moving unthinkingly to a problem-based approach risks losing the focus that allows expertise to develop. The challenge for the modern university is to balance the competing demands between developing mental schemas and using them.

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