Chapter 8 set out some of the main principles of probability including Bayes’s theorem and investigated the subjective interpretation of probability in terms of coherent degree of personal belief, ending with three core tenets of “pure (subjective) Bayesianism”. It also considered the ways in which Bayesianism captures a number of important aspects of scienti c method, including an account of con rmation and discon rmation and the good aspects of the hd method that survive within a probabilistic context, also providing it with a theory of con rmation. In this chapter we consider further successful applications of the probabilistic approach to methodology along with some problems for Bayesianism.