audience as possible and because I personally believe that it is easier to axiomatize a mathematical theory precisely than to dis­ cover it and enunciate its key theorems. Professor Polya said: "The truly creative mathematician is a good guesser first and a good prover afterward. " For centuries a formalized generalized logic was found necessary and many attempts have been made to build it. vi Preface Mine is based on plausibility which covers with precision a wider field than probability and makes the formalization of analogy and generalization possible. As Laplace said: "Even in the mathematical sciences, our principal instru­ ments to discover the truth are induction and analogy. "* The examples of application I have chosen are not des­ cribed in detail.