A preface presents the author with a privileged occasion where he may explain the aim he had in writing the book and apologize for not having attained it.
There exist already many books on the philosophy of science. However, most of them deal with quantum physics only and, moreover, their authors usually neglect to state clearly the philosophical terms of reference they have used.
My intention has been to give a reasonably complete account of the concepts, both of classical and of quantum physics. And I have tried also to make clear the methodology employed for explaining and arguing about these concepts.
The first part of the book therefore treats of modern logic and semantics; the discussion is based on the semantic conception of truth and leads up to the criterion of meaning. Our prime concern is, after all, to establish what our hypotheses, laws, and theories mean. The second, and main, part of the book is about the basic ideas of physics. Here the model which underlies a scientific theory is of greatest import; in most instances the model is tacitly assumed, but we must bring it out into the open if we want to understand the theory. The third, and last, part deals with the method scientists use for confirming their hypotheses. I have followed my own laboratory experience and tried to describe it in a manner which is closer to scientific practice than the usual 'armchair' accounts. The rôle the concept of probability plays in judging the result of an experiment is, in my view, quite different from what it is generally supposed to be.
The book is addressed to the layman who realises that science is an inalienable part of our civilisation and who therefore wants to understand it. The philosopher will find here a discussion of the concepts of physics in a language which I have tried to keep as close as possible to his usual way of speaking. But I hope that the physicist as well may find that to philosophize about his science can be of help in understanding it.
The book was written between the years 1947 and 1951; there