It is easy to take for granted what one is good at. (On this, see “How to Find Your Comparative Advantage.”) Economists often don’t appreciate the sophistication of the models they deal with in comparison to common ways of thinking. I point out to my undergraduate students that, relative to “P affects Q and Q affects P; it is the seamless web of history that can’t be untangled,” supply and demand is a big advance. And I point out to my graduate students how holding a co-state variable fixed as a step in the analysis of a phase diagram even when it won’t be fixed in the end is fully analogous to holding price fixed to develop supply and demand curves, that then make it possible to cleanly analyze equilibrium effects in which price is not fixed.

Another key example is this: relative to the idea that there are only two possibilities, A or B, that C is the one cause of D, or that either E or F are enough to get from one of two states to another, a model in which two different things have a linear effect on an outcome is a big advance. The two articles flagged above show the value of even a simple linear model for understanding, diet, health and exercise. Both eating right and exercising are valuable for health, and doing one doesn’t reduce the marginal product of the other that much. And the curvature in the effect of exercise on health isn’t big enough to keep more than the usually recommended amount of exercising from having a substantial positive effect.

Of course, the linear model, while almost always a good approximation locally, almost always breaks down eventually due to curvature. On that, see “The Golden Mean as Concavity of Objective Functions.” But note that a model with gradual curvature is strictly more complex than a linear model. A linear model is a key stepping-stone on the way to understanding a model with gradual curvature.

When I previewed the content of this post for one of my friends, the reaction was that this sounded like looking down on others. I don’t view it that way. We need to see what we are good at and what is hard for others in order to do the most good in the world. And conversely, we need to see what others are good at that is hard for us. And of course, we need to see what we and others are relatively good at. That is the essence of comparative advantage. It is a matter of mathematics that everyone has some comparative advantage! (At least weakly.)

Recognizing your own technical advantages makes it clearer what you have to offer, and the efforts you will need to make to explain an idea clearly given where your listeners are coming from. One of the best pieces of advice I ever got was one of the excerpts I was given from letters of evaluation when I came up for tenure. One writer said “Miles sometimes overestimates his audiences.” The translation is that what I was saying was obscure because I hadn’t given the appropriate background or had gone too fast.

People can be offended by being treated as if they have less background than they do, and on the other hand, they can be confused by being treated as if they have background that they don’t. There is no way around the need to get it right.