Ernst Mach

I’m an instrumentalist. Are you one too?

Over the past few years I’ve realized that there are a lot of scientists who have a different view of science than I do, and most of them don’t even know about my way of thinking. But my way of thinking about science – Instrumentalism – is cool! I’m writing this post to explain what Instrumentalism is, and why I prefer it to other ways of thinking about science. At the very least I can link back to this from future posts so that you’ll understand why I say certain things. Maybe you’ll agree with me that Instrumentalism is cool. Maybe you’re already an Instrumentalist and you didn’t even know it!

Instrumentalism is the idea that scientific theories can never be proven wrong or right. Instead, theories are tools for understanding and prediction. They can be judged as better or worse tools, but that depends entirely on the context: what’s being explained to who and what’s being predicted, under what circumstances. Scientific models have the same status. In one of the most famous cases, the movement of the sun relative to the Earth, neither Ptolemy’s geocentric model nor Copernicus’s heliocentric model would be considered “true” or “false.”

This view of theories does not mean that there is no truth or falsity in science. Observations can still be accurate or inaccurate. And critically, hypotheses can be confirmed or rejected. These hypotheses are usually based on a theory, and a theory that predicts a lot of falsified hypotheses is not a very useful theory. So the heliocentric model is more useful than the simple geocentric model for predicting the movements of planets because those predictions are more often correct.

On the other hand, the geocentric model must still be useful, because most people continue to use it every day. If you’ve ever talked about the sun “rising,” you’ve used a geocentric model. It’s a lot easier than talking about part of the earth’s surface rotating away from the direct rays of the sun. The geocentric model’s predictions about the sun’s behavior are perfectly adequate for day to day human activity.

Since theories are tools for understanding, they are more useful if they are based on a simple analogy to something familiar. The geocentric model compares the sun to flying birds and jumping horses, or to spheres and hoops. In order to explain the apparent “retrograde motion” of the planets, astronomers added the ugly and counterintuitive “epicycles” to the geocentric model. But the sun does not exhibit retrograde motion, so there are no epicycles to spoil its simplicity.

This means that an astronomer (or any of us watching a movie about space) will likely use both the heliocentric model and the geocentric model on the same day, or even in the same hour. In a view of science which says theories are true or false, what does it say about someone that they use two different theories to model the same phenomenon on the same day? Maybe that person is a hypocrite, or even worse, weak-minded for not having the will to consistently apply the true model.

In contrast, instrumentalism is pluralist, tolerant and understanding. Of course sometimes we all act like the sun goes around the earth. It’s the simplest, most straightforward way to think about it!