You dive into the research and read the literature until your eyes bleed.

After a while, you think you’ve got a handle on things. You head out into the world and start talking to people. They tell you things that prompt new questions. Certainties melt in the face of facts.

And suddenly what seemed so clear a few weeks ago is a muddle. You regroup, and weigh the evidence.

I came to call these “it’s-not-what-you-think” moments. Here are three of them.