On rereading the text of my Tarner Lectures I was at first tempted to expand the arguments, to tone down the style, to present a range of alternative interpretations in the discussion of quantum mechanics, to add many more footnotes and references and other scholarly paraphernalia – in short to turn the Lectures into a monograph. But on reflection I decided to do none of these things. I came to Cambridge in 1987 with a certain missionary enthusiasm, to defend the objectivity and rationality of science, and to develop the new discipline of the philosophy of physics, and the Tarner Lectures afforded an opportunity to make a sharp, if at times simplistic, statement that would represent to a wider audience the sort of thing that I and my colleagues and students were trying to do.

So I have left the text more or less as a verbatim report of the Lectures as I delivered them. I leave it to the reader to decide whether I would have produced a better book if I had written a different book.