 Ramsey’s central goal in ‘Truth and Probability’ is to show that the laws of probability provide us with a ‘logic of partial belief’ – that is, the laws specify general necessary conditions on any consistent set of partial beliefs, in a manner analogous to how the laws of classical logic might be taken to generate necessary conditions on any consistent set of full beliefs. The argument for this claim is grounded in Ramsey’s novel approach to probability, namely subjectivism. The essay begins, however, with a discussion of the two major approaches to understanding probabilities at the time in Cambridge: frequentism, and a version of the logical interpretation put forward by the economist John Maynard Keynes in A Treatise on Probability (1921).