By Gordon Rugg
Mental models provide a template for handling things that happen in the world.
At their best, they provide invaluable counter-intuitive insights that let us solve problems which would otherwise be intractable. At their worst, they provide the appearance of solutions, while actually digging us deeper into the real underlying problem.
In this article, I’ll use a cup of mocha as an example of how these two outcomes can happen. I’ll also look at how this relates to the long-running debate about whether there is a real divide between the arts and the sciences as two different cultures.
Hot drinks are an everyday feature of life for most of the world. Precisely because they’re so familiar, it’s easy to take the key attributes of hot drinks for granted, and not to think about their implications.
I’ll start by listing some of their attributes, and comparing these attributes with Lego bricks, as another everyday item that most readers will know. At this stage, the attributes look obvious to the point of banality.
I’ll then look at how the features of hot drinks can map on to types of problem in the world, and onto worldviews.
The attributes I’ll look at are as follows.
Reversibility: Making a hot drink involves combining ingredients with hot water. Once you’ve combined them, you can’t un-combine them; the process is non-reversible. This is very different from the situation with Lego, where you can combine blocks to make a structure, and then take that structure apart and end up with the same blocks that you started with.
Localisability: Before you make a hot drink, you can point to each of the ingredients separately and say where they are. After you make a hot drink, the ingredients are no longer separate; it’s meaningless to ask where the chocolate is in a cup of mocha, because the chocolate is everywhere within the mocha. With Lego, in contrast, you can still point to each individual block within a structure after you have made the structure.
Measurability: You can easily measure the ingredients of a cup of mocha before they go into the drink. However, you can’t easily measure the ingredients of a hot drink after that drink has been made; for instance, finding out how much sugar was added. With Lego, in contrast, it’s easy to find out how many blocks of a particular type are in a structure after that structure has been made (for simplicity, I’m assuming a small number of blocks in a small structure so that they’re all visible).
Interactivity: A hot drink can change things that it comes into contact with. It can stain clothes; it can scald flesh, if the drink is very hot; it can turn paper into a soggy mess. Lego doesn’t do any of these things.
There are some obvious-looking similarities between the mocha/Lego contrasts and the contrasts between traditional views of the humanities and the sciences. The subject matter of the humanities, like mocha, doesn’t generally consist of clearly separate entities that are easily counted; instead, the humanities deal with intermingled entities that can be measured to some extent. With Lego, as with traditional models of science, it’s easy to disassemble a structure and see what happens if you reconfigure it; with mocha, and the humanities, this isn’t possible. You can’t re-run history, and you can’t raise people in an experimental setting the way that you can do with lab rats.
It’s also fairly obvious that the divide between the traditional humanities and the traditional sciences is an over-simplification. Within fields such as sociology and psychology, there is a long tradition of using sophisticated numerical, statistical, methods to study human behaviour; within fields ranging from nuclear physics to hydrodynamics, there’s a long tradition of using models that have much more in common with mocha than with Lego.
I’m taking these issues pretty much as given, and as well known. What I’ll focus on instead in this article is the bigger picture. What happens when you try to systematise the choice of appropriate mental model for a particular problem? What are the issues that you need to include, and what are the implications if you get it wrong, or only partly right?
Stains, sin and mana
I’ll start with the issue of implications.
A lot of the issues that people have to deal with in life involve abstract concepts, such as justice, or involve entities that aren’t observable with normal human senses, such as bacteria that cause diseases. This is where mental models based on familiar parts of the physical world can come in very useful; they provide a ready-made framework for handling abstract concepts, and entities that aren’t easily observable.
A classic example is the concept of cleanliness, which has been much studied within fields such as anthropology and theology. In current Western culture, cleanliness tends to be viewed as a medical issue, separate from religion and morality. This, however, is a recent development. Historically, cleanliness has been treated by most cultures as something much more associated with religion and morality.
In many cultures, for instance, there’s a distinction between the clean and the unclean. Usually, a person or an object can become unclean as a result of physical contact with something unclean (e.g. a dead body, or a grave). The underlying model here is very similar to someone or something being stained by contact with a liquid. The usual solution involves a cleaning process, often involving either some form of bathing, or some form of sacrifice, where the blood of the sacrifice washes away the spiritual contagion.
A key point here is that the uncleanliness doesn’t need to involve sin or immorality. It may happen to involve them, but it doesn’t necessarily have to. For instance, someone may accidentally become contaminated, and can then become clean after they perform the cleaning process.
This underlying principle of contagion is still widespread within Western cultures that have adopted the medical model of cleanliness.
An example is the market for objects once owned by celebrities. A pen owned by Napoleon would sell for much more than an identical pen which had not been owned by him. There’s no objective difference in the inherent properties of the two pens; what’s different is that one has been touched by him, and the other hasn’t. The converse also applies, with most people being reluctant to own or use items associated with notorious criminals. In both cases, the underlying mental model involves a spiritual stain, either good or bad, left behind by contact with the famous or infamous individual.
This model is well recognised in social anthropology, where it’s usually known by the Polynesian name of mana. Within this mental model, mana can be spread by contagion, like a stain from coffee. However, there is a key difference; in most belief systems which use mana, mana can also be spread by similarity. For instance, if someone wears the same type of clothing as a high status individual with a lot of personal mana, then the imitator will acquire mana as a result. There are entire industries making significant amounts of money out of these two principles.
So, in brief, the “stain and cleaning” aspect of the mocha model plays a significant role in worldviews.
What about other aspects of the mocha model and the Lego model? This is where there’s a strong argument for a more systematic study of mental models.
For everyday life, mental models are particularly useful for predicting what will happen next, in a new situation. Mental models are also used on an informal basis within research, usually as a source of useful metaphors and analogies.
However, if we look more formally and systematically at mental models, then we start to see deeper implications. There’s a whole body of research on how this relates to teaching topics such as physics, where people’s everyday mental models work to some extent, but then fail in other situations.
Flawed models can have tragic real world consequences. A striking example occurs in Barbara Tuchman’s book The Guns of August, about the start of World War I. A repeated theme is that the Germans expected defeated nations, such as Belgium, to accept the reality of overwhelming force, and to obediently do as they were told by the German authorities. The German high command appeared to be genuinely astonished when this didn’t happen.
So what was going on with that mental model?
One possible explanation is that it was an “Other as dark reflection” model, where a different group is perceived as being the opposite to the in-group. In this model, the in-group would resist being told what to do by invaders, because the in-group is brave and independent, but other groups would behave differently, because they are the opposite of the in-group.
This, however, did not appear to be the case in August 1914; Tuchman records German comments to the effect that Germans would not behave in such an insubordinate way if the roles were reversed.
A more likely explanation for this particular case involves something deeper in the mental model. A frequent feature of mental models, include the mocha and Lego models, is that their predictions run for one or two steps, and then come to a natural end. You add hot water to the ground coffee, and then you have a cup of coffee. You add blocks to a Lego tower, and it gets higher; if you go too high, it becomes unstable and falls over. Things then stay the same until some external intervention occurs.
This is very different from what happens within a system, in the formal sense of the term. A key feature of systems is that they can include feedback loops, where changes can go on happening for multiple steps, and may continue indefinitely. These changes are often counter-intuitive, in ways that have far-reaching implications.
So, how do you set about choosing the right mental model for a given problem, and how do you know whether your mental toolbox includes all the models that it should include?
I’ll go into this theme in the next article in this series, which will look at Meccano, engineering models, and systems theory.
Notes and links
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There’s more about the theory behind this article in my latest book:
Blind Spot, by Gordon Rugg with Joseph D’Agnese
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