1 In 1954 Karl Popper published an article attempting to show that the identification of the quantitative concept degree of confirmation with the quantitative concept degree of probability is a serious error. The error was presumably committed by J. M. Keynes, H. Reichen- bach and R. Carnap. 2 It was Popper's intention then, to expose the error and to introduce an explicatum for the prescientific concept of degree of confirmation. A few months later...