Models: Multiplicity

In a previous post, I talked about science being all about making models. You observe a lot of phenomena, then you try to make a model that represents your observations. By creating a model, you make a generalization that (you hope) will apply to things you haven’t seen as well as the things you have.

But there’s a huge caveat that applies here: sometimes different models can be used to represent the same phenomena.

Most famously, light can be modeled as a wave or a particle. (Light is also modeled as a ray in Geometrical Optics.) It’s important to stress that these are models. We’re sometimes sloppy and say that light is a wave or a particle, but that’s going too far. Light is light. Waves and particles are models that help us predict how light will behave, and although they’re excellent models, they’re abstractions. We can’t say they’re real.

Another famous example of models are the different ways to represent the solar system, specifically the Copernican and Ptolemaic models. It’s well known that the Ptolemaic system used to fit observational data better than the Copernican model did, at least to begin with. Ptolemy’s system of multiple spheres had so many fudge factors that it could be adjusted to match reality pretty closely, whereas Copernicus had problems because he tried to use circular orbits instead of ellipses. But in the long run, the Copernican model was modified to become more accurate, and it “won” because it was much much simpler than Ptolemy’s spheres.

As another example, think of maps. Maps are models: abstractions of actual landscapes. We have road maps, topographical maps, numerous kinds of geological maps, and much more. Each can be based on the same terrain; the difference depends on what you choose to include and exclude.

Let me emphasize exclusion. The whole point of a map is that you leave things out for the sake of simplicity. Maps only show a tiny subset of what’s actually on the ground. They may also exaggerate the size of some geographical objects so they’re easier to see; a road map, for example, shows roads much wider than they would be if they were actually drawn to scale. We might say that maps are deliberately wrong—they deliberately hide some things and distort others in order to make certain information more comprehensible.

The same is true of economic models. The actual economy is hopelessly complex; it consists of a huge number of transactions between people, companies, governments, and other organizations. No model could possibly capture so much complexity. As a result, economic models make enormous simplifications—they ignore almost everything that actually happens.

We all know how that can lead to problems. Different economic models arise from ignoring different things, and what you ignore may be precisely what bites you in the ass during a financial crisis.

But my favorite example of multiplicity in models is what we see in role-playing games. Every RPG contains a system for representing characters: often a list of numbers and abilities aimed at modeling human beings (or human-like entities). Different games use different models…and while some game systems are moderately similar to one another, others are wildly divergent.

Even more interestingly, slight differences in models can lead to substantially different gaming experiences. The Call of Cthulhu character model, for example, is pretty close to a lot of other models, except for a single number: a ranking of your sanity. That SAN rating takes on an overwhelming importance as you play the game. Sanity considerations can affect every action taken by individuals and by entire groups. It gives the game a much different ambiance from games that might otherwise be similar.

My point is that models are chosen, and often by selectively omitting or exaggerating details. Models often impose and reinforce a view of what is and isn’t important. This has consequences…and in the next installment of this series, I’ll take a look at what those might be.

[Picture of Cthulhu by Alexander Liptak. Image used with permission under Creative Commons repository. Attribution 3.0 Unported licence.]

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