Re John Davis' query: I vote for opportunistic application of a shell discourse (neat phrasing there, John) over natural product of formalism. It's more problematic for me, as a historian, because more than a few economists have discovered they can get away with a LOT in terms of bluffing what economic theory is, since most historians have very little training, and less understanding, about mainstream economics today. So none of you have heard mainstream economists use this, eh? That's interesting. (I have, but only around economic historians or historians.) How about using pareto optimality, or pareto superiority, as the yardstick for social welfare? Seems to me to conveniently exclude initial endowments of wealth and/or power as issues in a situation where they are very much issues. And it might give a local optimum, but can't possibly answer questions about POTENTIAL welfare. Perhaps some of the language I'm hearing in economic history is an extension of this line of reasoning. (If no trade will make anyone better off, social welfare is maximized.) -- Mary Schweitzer