Does GNP Measure Growth and Welfare?

The question posed by the title to this lecture raises a number of deep problems of economic science. The question seems simple, yet in these few words — measurement, growth, and welfare — culminate the problems of large areas with which economists have been concerned for centuries. How nice it would be then if one could report that now we have one single concept and, indeed, one single number which could summarize variations of growth and welfare. As we shall see this unfortunately is not the case.