The following is an attempted answer to the question: in what kind of world is learning from experience possible? The method is to build up imaginatively a world until what has in general outline been constructed is such as to permit the kind of learning by experience with which we are all familiar. We may hope that some interesting facts even now may emerge from a consideration of this trite subject. Not all that we know has been learnt from experience, though, no doubt, anything we know, if it has come to our notice, has done so in the course of experience. With this truth we are not concerned. Our subject is what is called “empirical science”; but by sometimes calling it by the homelier name appearing in the title of this paper, we may remind ourselves that we are not dealing with a specialist branch of knowledge or a technical subject, but with what is a necessary feature of even the most commonplace experience.