I have been a Bayesian since I first learned Bayes’ theorem when I was a teaching assistant for a Statistics 101 course at UC Berkeley around 25 years ago.

It’s one of those neat ideas that one should know to be able to reason competently about the world we live in. Thanks to the Indian education system, I had not been exposed to any hint of that fascinating rule in my 18 years of attending school in India. Anyway, better late than never.

The late great John McCarthy insisted that “he who refuses to do arithmetic is doomed to talk nonsense.” I think he who is ignorant of Bayes’ rule cannot avoid talking nonsense about probabilistic events. Consider the question posed in the image above. Continue reading →