Over the last year, I’ve watched with horror and amusement as health agencies around the world flip-flopped their advice on how to deal with COVID.

My horror comes from knowing this flip-flopping breeds mistrust in science. But I am (morbidly) amused because I know that uncertainty is a basic part of real research. For the public, ‘science’ tends to mean authoritative knowledge. But for researchers, ‘science’ is an iterative process, filled with wrong turns, new evidence, and revised ideas.

With COVID flip-flops in mind, I thought I’d tell you a story about science in progress. It’s a story about how we should understand the stock market.

Three stories about the stock market

Here are three stories about how the stock market works.

The first story says that the stock market reflects the productivity of the underlying economy. When stocks go up, the thinking goes, everyone should celebrate because the tide…