After reading Kevin Drum, I got ready to go off on a long tangent about how if you just sit down and think about it you can tell that the standard explanation of how an airplane flies is shaky at best.

Interestingly, Mike then brings up an analogous scientific question that I was going to mention because I got it wrong for a very long time myself. Namely, how does an airplane wing work? I had long been under the impression that it had something to do with air traveling faster over the top surface, thus producing a vacuum and generating lift. But just like the orbit of the earth, which is quite obviously not a good explanation for the seasons since it’s summer in Australia at the same time it’s winter in London, this is quite obviously a lousy explanation for lift since planes can fly upside down.

But, I’ll resist the full tangent and try to make this more tolerable and productive.

At the core we always want to appeal to simplest and most direct law we can think of. The airplane is thrown “up”. Conservation of momentum then says something in the universe must be thrown “down.”

Our most likely candidate is the air. Then the answer to how the plane goes up must be the answer to how the air goes down. Does your standard explanation tell you that?

My larger point though is though is this

When analyzing things that have a political dimension – like economic policy – people suddenly become aware of the shakiness of the scientific lessons they have been taught. However, this pervades all of science. Its just that most of the time people don’t stop and ask.

In one case that I face all of the time, I talk to lots of folks about the obesity epidemic. The baseline assumption for people at all sorts of levels on this issue is that obesity results from people eating too much and exercising too little.

To explain that this is a maddeningly ridiculous non-answer is like pulling teeth. I am not going to do the whole dog and pony show but for those who might be hearing this from me for the first time ask yourself: how then do people wind up eating and exercising the “right amount.”  Because, the answer to that question must be dual to how they might end up eating and exercising the “wrong amount” – whether too little or too much of either.

In any case this is repeated over and over again through pop science. Few people question ideas that if you stopped to question you would see that the standard answer is ridiculous and likely something someone told you so you would stop bothering them.

Indeed, we have textbooks full of “stop bothering me” answers to questions about how the world works. Still, many of these answers are quite useful for common purposes even if they don’t make any sense.

So, what you’ve uncovered with economics and public policy is not how a weirdly shaky discipline but simply how shaky our understanding of the world is generally. Or, at a minimum how complex and narrow the solid answers are.