  To understand what Ramsey means by “degree of belief in \(q\) given \(p\)” we need to turn to his earlier essay “Truth and Probability” (1926a), where he develops an interpretation of probability as the logic of partial belief ([FM] 157).  (Note, Ramsey did not take this to be the only notion of probability: “The conclusions we shall come to as to the meaning of probability in Logic must not … be taken as prejudging its meaning in physics” (ibid.). The editor adds that a final chapter, on probability in science, was designed but not written.)  Here he introduces a “very useful new idea – ‘the degree of belief in \(q\) given \(p\)’” (1926a, [FM] 180). One of his basic laws is: