The Use of Models

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Photo by Oregon Department of Transportation via Wikimedia Commons.

Have you ever been lost? I don’t mean it metaphorically, as in “I don’t follow what you’re saying.” I mean have you ever not known where you are — physically — and not known how to get to where you want to be? It’s terrifying. I’ve been lost a couple of times. Once when I was a kid, I got separated from my family while we were skiing. I had no map, and this was in the middle of a whiteout, so I couldn’t see where I was going even if I did. I’d also lost one of my skis. (Don’t ask.) Like I said, terrifying. I got out of the situation by following a simple heuristic: “keep going down the mountain.”

In situations such as this one, you run the risk of panicking and freezing. (In this case, literally.) You must find ways of taking skillful action — that is, acting in ways that get you closer to your goal. (In this case, reconnecting with my family at the lodge. And ideally, hot cocoa.) You act based on your understanding of your current situation: where you are, what options are open to you. But often we can’t see these things clearly, as happened to me on that mountain.

Fortunately for me, I wasn’t completely lost. I had a few things going for me. For one, I knew I wasn’t in the wilderness; I was within the confines of a ski resort. There are boundaries to such a place and facilities (a lodge) where people congregate. I also knew there were some other people around me. (Not many; it was not a nice day on the slopes. But still.) Most importantly, I knew the general direction I needed to go towards: down the mountain, where the lodge is. In other words, I had a model of the environment in my mind: I’d reduced the mountain’s complex network of runs to a simple choice: up or down. I knew “down” was where I needed to go.

Systems (such as the ski resort) are sets of elements that are interrelated in particular ways that allow them to serve particular purposes. You enjoy skiing because the side of the mountain has been groomed into distinct runs, equipment (such as skis, poles, and chair lifts) has been installed, facilities (such as the lodge) built on the site, people with specialized roles (instructors, safety personnel) hired, and so on. The elements that comprise the ski resort interrelate in various ways to help you go up and down the mountain safely.

The real-world inventory of elements and the relationships between them are incredibly complex. Understanding such a system requires that you create an abstract representation in your mind. When considering which chairlift to board, or which run to go down on, you don’t need to know about the exact location of every tree in the mountain; in fact, such knowledge would probably hinder your ability to act. So you filter stuff out. You create a model.

A model is a representation of a system that leaves stuff out. The key is in what you leave out. When you draw a map of the trails on a mountain, you don’t show the location of every tree. That wouldn’t be useful in helping you figure out where to go next and only adds to the signals your mind must process. Models help you make decisions; the good ones leave out the stuff that doesn’t help you decide. If what you’re trying to do is navigate the runs on the mountain, leaving out the individual trees makes sense. (However, that may be useful if you’re studying the spread of disease among the evergreens, in which case you probably wouldn’t care as much about other details of the environment such as the floor plan of the lodge.)

When I was lost in the mountain, I abstracted the place to a very simple model that had only two directions: “up” and “down.” This model wouldn’t be very useful in other situations, but given the information I had at that moment, it was ideal. As I hobbled down the mountain, fingers and toes numb, visibility gradually improved. At first, I could make out the edges of the run. Then, I could see junctures where the run branched. As I progressively gained my bearings, I became more confident in​ the choices I was making. I became calmer and acted more skillfully. Eventually,​ I stumbled onto a sign with a map, and from there it was relatively easy to make it back to the lodge.

To me this story captures the value of models: they’re abstractions that help us decide and act skillfully while having incomplete information. (Or rather, because they give us incomplete information.) As we act under the guidance of a model, our understanding gradually becomes more complete, allowing us to act more skillfully. We refine the model as we know more about the situation, creating a virtuous cycle of understanding. But we must start somewhere. This requires that you know what to leave out, and this, in turn, depends on what you’re trying to do.