Roughly two-hundred and fifty years ago, the key to justifying all knowledge about the observable universe was discovered by the English Mathematician Reverend Thomas Bayes. It is a very simple, self-evident statement, which makes it so much more remarkable in light of how many problems it solves. The name of the “key” is Bayes’ Theorem, and it justifies and describes not only all correct scientific reasoning, but also all correct historical reasoning and even ordinary, common sense reasoning. It is the grand unified theory of human knowledge, and you have probably never even heard of it. Little wonder: It is a tool that is so powerful that many discoveries about the theorem were kept as classified secrets of the U.S. government during World War II (For a history of Bayes’ Theorem and how it was used during the Wars, see The Theory that Would Not Die).
Roughly one hundred years after Reverend Bayes passed away, another dangerous discovery was made. Like Bayes’ discovery, it too was a grand unifying theory, only this discovery was the key to unlocking the secrets of life instead of human knowledge. It too was misunderstood and was targeted with propaganda. It too is simple and, in hindsight, obviously true. The theory I speak of is Charles Darwin’s theory of evolution by natural selection. Though Darwin’s ideas are not entirely original to him (his grandfather, Erasmus Darwin, was also an evolutionist, and several others preceded him, including some ancient thinkers, see Creationism and Its Critics in Antiquity), he nonetheless deserves his place as the front and center figure of evolutionary biology, for he is the one who turned armchair speculation into a bona fide scientific explanation. He is responsible for relentlessly developing the idea of natural selection from a seemingly trivial principle into a powerful driving force capable of producing the wonders of the natural world like the eye, the wing, and even the brain. He cracked the code that lay behind the curious patterns and commonalities shared between species with an explanation that is both compelling and testable.
Philosopher Daniel Dennett once said, “If I were to give an award for the single best idea anyone has ever had, I’d give it to Darwin, ahead of Newton and Einstein and everyone else. In a single stroke, the idea of evolution by natural selection unifies the realm of life, meaning and purpose with the realm of space and time, cause and effect, mechanism and physical law.” (p.21, Darwin’s Dangerous Idea) Even Dennett would have to concede that Rev. Thomas Bayes runs at least a close second to Darwin for this prize: He, in a single stroke, united the realm of logic and mathematics with the realm of probabilistic, observation-based reasoning.
The purpose of this series is to explain the ideas of Bayes and Darwin and to unite the two by showing that Bayes’ Theorem proves Darwin was right beyond all reasonable doubt.