ABSTRACT
Let me remind you that we are to be concerned, within the book's first four parts which are treated within the traditional framework of assumptions, almost entirely with comparative statics; with the ranking, that is, of alternative equilibrium situations. Working within a partial economic context, as we are doing now in Part Two, it happens to be easier to measure differences in net social value or benefit. Thus we are able not only to rank alternative situations within this context, but we can put figures on them and on their differences. Yet this apparent facility in measurement is, in part, the result of a number of simplifications built into the method. In order to assess the validity of such measurements we have continually to bear in mind the simplifications frequently used and the likelihood of their being approximated in the particular instance.
