  Andrei Kolmogorov's Grundbegriffe der Wahrscheinlichkeits-rechnung put
probability's modern mathematical formalism in place. It also provided a
philosophy of probability--an explanation of how the formalism can be connected
to the world of experience. In this article, we examine the sources of these
two aspects of the Grundbegriffe--the work of the earlier scholars whose ideas
Kolmogorov synthesized.
