How and Why Did Probability Theory Come About?

This paper is a top down historical perspective on the several phases in the development of probability from its prehistoric origins to its modern day evolution, as one of the key methodologies in artificial intelligence, data science, and machine learning. It is written in honor of Barry Arnold's birthday for his many contributions to statistical theory and methodology. Despite the fact that much of Barry's work is technical, a descriptive document to mark his achievements should not be viewed as being out of line. Barry's dissertation adviser at Stanford (he received a Ph.D. in Statistics there) was a philosopher of Science who dug deep in the foundations and roots of probability, and it is this breadth of perspective is what Barry has inherent. The paper is based on lecture materials compiled by the first author from various published sources, and over a long period of time. The material below gives a limited list of references, because the cast of characters is many, and their contributions are a part of the historical heritage of those of us who are interested in probability, statistics, and the many topics they have spawned.