books science technology

Escape from Model Land, by Erica Thompson

Mathematical models don’t often get a lot of attention from the general public. When they do, it’s rarely positive. Perhaps they have failed to predict a recession, or foretold pandemic doom scenarios that don’t materialise. All of a sudden it gets political, and everyone is talking about a science that they may or may not understand.

For those who do want to understand what models are and what they can do, Erica Thompson has written a very useful book: Escape from Model Land – How mathematical models can lead us astray and what we can do about it. She’s a data scientist and fellow at the London School of Economics, with a background in climate modelling. Her book is a clear and a surprisingly playful exploration of what models can and can’t do, when they’re useful and when they’re not.

Models are frameworks for thinking. They are how we form relationships between data, in order to understand the future. And while the focus is on mathematical models, Thompson takes a wide definition. We all use models all the time, even subconsciously. When we decide whether or not to take an umbrella with us as we leave the house, we assess the conditions outside against our past experience of weather and seasons. It’s a simple modelling exercise that will result in a best guess at chances of rain, and that will inform our decision.

Of course, the models the book is most concerned with are computerised and complicated, including the ones used by weather forecasters. Others are used to forecast election results, monitor volcanic activity, model consumer behaviour in order to advertise to us, manage the economy or coordinate disaster response. We can’t avoid models. All the more reason to understand them.

In the second half of the book there are specific chapters on economic, pandemic and climate modelling, but these are low on specifics and more concerned with the theory behind efforts to model such things. Overall, the book is quite philosophical in tone. It talks about how, in George Box’s famous phrase, “all models are wrong, but some are useful.” Thompson looks at models as metaphors, fictions, how they function culturally and politically. The national economy described as a household budget, for example, is a simplified model that politicians have used to justify their actions in what sound like common sense terms, but don’t reflect the money creating powers that governments have.

Another thing politicians do sometimes is claim to follow the science, and Thompson warns about this. It’s in the jump from the neatly defined parameters of the model back to the real world that things most often go astray, and why Thompson calls the book Escape from Model Land. Models cannot make decisions. Models are created by people and interpreted by people. The lines of accountability trace back to the creators of the model, their assumptions and their biases and blind spots. Inevitably, sophisticated mathematical models are created by highly educated people in well funded institutions, and that position of privilege affects what their models see and don’t see. Without acknowledging this, following the science can be a way of blurring responsibility. Ultimately it is up to human beings to bring in the values that models can’t help us with, and “meaningfully integrate concepts such as care, love, responsibility, stewardship and community.”

The book investigates all of this with metaphors and thought exercises, and Thompson has more fun with it than you might expect. There are birthday cakes, comparisons with astrology, the butterfly vs the hawkmoth effect, “the cat that looks most like a dog”. It’s full of creative ways of explaining things. It’s not technical, though readers with an interest in mathematics, computing and data will definitely get more from the book. And I finished it much better equipped to think about models and how we use them well, humbly, inclusively and with accountability, in our social decision making.

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