A Treatise on Probability
A Treatise on Probability, published by John Maynard Keynes in 1921, provides a much more general logic of uncertainty than the more familiar and straightforward 'classical' theories of probability. This has since become known as a "logical-relationist" approach, and become regarded as the seminal and still classic account of the logical interpretation of probability (or probabilistic logic), a view of probability that has been continued by such later works as Carnap's Logical Foundations of Probability and E.T. Jaynes Probability Theory: The Logic of Science.
Source: Wikipedia — A Treatise on Probability (CC BY-SA 4.0)