¹ Some of the topics presented in the new appendices are: a formalization of probability theory in which p(a,b) = 1 if p(b) = 0; arguments designed to prove that the ‘absolute’ probability of a law is always zero and hence the conditional probability of a law given any evidence is always zero; criticisms of Carnap's proposal that a statement x is confirmed by evidence y if and only if p(x,y) > p(x); an explication of the concept of degree of confirmation or corroboration and a discussion of the concept of physical necessity.