Beyond the level on which we say that the only logical method of anticipating the future is to project the past, there is the level of the everyday practice of logic. Here our confidence in logic arises from our examination into the details of how logic works in practical applications. On this level we recognize that the elements of a logical analysis must have some of the properties of the “things” of experience, in particular, permanence and identifiability. On this level there is no sharp dividing line between the inductive and deductive logic. For both logics demand identifiability and repeatability, which themselves are not sharp concepts and demand a projection of the past. Furthermore, as usually practiced, the premises of our deductions are obtained by inductive methods. When we say that all men are mortal we very seldom have behind us a verification by observation of all men, but the statement implies an inductive generalization of some sort.
~P.W. Bridgman, The Way Things Are, p. 118