 In 1950, Carnap published what would be longest book of his career by far, the Logical Foundations of Probability, into which he worked these two papers (much expanded) and several others, and also went into great detail to bring a number of perspectives to bear on the clarification of the explicanda of “probability” and “confirmation” (both in the sense of probability1). He also goes into detail to discuss ways of arriving at axioms, and to motivate the choices he ends up with. In the course of these clarifications he addresses a number of philosophical issues surrounding induction, confirmation, and scientific inference. A simpler exposition than Carnap himself gave of his inductive logic project was given later by Kemeny (1963). See the supplement  Inductive Logic  for further details. 