Being (even more) Bayesian

Bayesianism has become my favorite math-idea-that-doesn’t-involve-math. It’s three simple steps. Step 1: have an idea about a thing. Step 2: observe the thing. Step 3: have a new idea based on the observation. (repeat)

There are two tricks to make this work for you. The first is how much to update. Being Bayesian means changing your mind in proportion to the change. Try the expression, “I’m slightly more sympathetic to X,” for example. Saying this acknowledges the new information and massages the ego.

The second trick is where to start (Step one), and we have to start somewhere.

“By not taking advantage of the accumulated knowledge that we have as a scientific community, we are artificially leveling the playing field. We are giving theories with no basis in scientific fact too great of a chance to prove themselves through the data.” – Aubry Clayton, The Conversation, August 2021

Clayton’s context is Covid19, but he touches on a larger point too. How much coordination and decentralized command a system allows.

A decentralized command iterates quickly. From the front lines of fast food to fashion to fights. If an organization wants to move fast, the decentralized command structure works better than coordination.

But while individual agents may be fast, the whole may be slow. Why? No coordination. The scientists in a medical research lab will do more experiments with no oversight or collaboration but they may not make more progress.

Coordination and decentralized command apply to both knowledge and people. Having accurate base rates and priors means coordinating our existing knowledge with the accumulated.


Bayesians even frame things beautifully. It’s not “changing your mind” bur rather it is “updating your beliefs”.