What's the first problem that DeLong points to in his second big lesson for Econ 1 students?
First, the market will go wrong if the wealth distribution is wrong. The market judges value by willingness to pay, and the rich are much more willing to pay them the poor, and those without wealth or income have no willingness to pay at all. If your wealth and income are zero, then the market literally does not care whether you live or die--it is of no interest to it at all.Well, it might go wrong relative to Brad's SWF that worries a lot about poor people. But what makes Brad's "not wrong" point on the contract curve any better than mine?* You have to point to something outside of economics to make the case for one point over another, barring the point that emerges as outcome of voluntary trade from folks' initial endowments so long as those endowments are also the result of prior voluntary trade. That point on the contract curve gets slight privilege as moves away from there in the real world will encounter leaky bucket problems if we can't run the transfers of endowments without incentive effects.
I'm not saying that we shouldn't care about the poor, or that there might not be good reasons for wanting redistribution to get to a different point on the contract curve (of a likely somewhat smaller Edgeworth Box). But I'd not say that markets have "gone wrong" if we wind up at some point on the contract curve that isn't my favorite one.
*For my favorite point on the Edgeworth Box, draw it as follows. In the bottom left hand corner, write "Eric". In the top right hand corner write "Everyone Else". Label the horizontal and vertical axes as being two composite commodities that Eric views as goods: horizontal can be "All the good things that begin with the letter B", vertical can be "All the good things that do not begin with the letter B". Draw a contract curve stretching from bottom left to top right. Draw some indifference curves too, if you like, noting what the labeling of the axes implies about the shapes of the curves. Write in a nice title for the box too. Then, put a great big dot on the top right hand corner that says "Markets haven't gone wrong". For all other points on the contract curve, write "Markets went kinda wrong". Put a small dot somewhere close to the bottom left hand corner, on the contract curve, labeled "Brad thinks markets went right (but they didn't). For all points off the contract curve, write "Markets went really wrong - Pareto inferior solutions".