Life is constantly making demands on me to move and keep moving. I have to gamble on some things; I go with my best horses, my oldest, most successful and trusted concepts. And sometimes, I change my mind.

This mental flexibility on my part means that the critics of Bayesianism simply haven’t grasped its spirit. Bayesianism is telling us pretty much what Thomas Kuhn said in The Structure of Scientific Revolutions. We are constantly adjusting our concepts to try to make our ways of dealing with reality more effective.

And when a researcher begins to grasp a new hypothesis and the model or theory it is based on, the resulting experience is like a philosophical or religious “awakening”—profound, all-encompassing, and even life-altering. Everything changes when we accept a new model or theory—because we change. In order to “get it,” we have to change. We have to eliminate some of the old beliefs from our familiar background set.

And what of the shifting nature of our view of reality and the gambling spirit that is implicit in the Bayesian model? The general tone of all our experiences tells us that this overall view of our world and ourselves, though it may seem scary or perhaps, for more confident individuals, challenging—is just life.

We have now arrived at a point where we can feel confident that Bayesianism gives us a solid base on which to build further reasoning. Solid enough to use and so get on with all of the other thinking that has to be done. It can answer its critics decisively—both those who attack it with real-world counterexamples and those who attack it with pure logic.

For now, then, let us be content to summarize our points so far in a new chapter devoted solely to that summing up.

Notes

1. Thomas Kuhn, The Structure of Scientific Revolutions (Chicago: The University of Chicago Press, 3rd ed., 1996).