Paul Krugman: What Markets Will

In the Middle Ages, the call for a crusade to conquer the Holy Land was met with cries of “Deus vult!” — God wills it. But did the crusaders really know what God wanted? Given how the venture turned out, apparently not.

Now, that was a long time ago, and, in the areas I write about, invocations of God’s presumed will are rare. You do, however, see a lot of policy crusades, and these are often justified with implicit cries of “Mercatus vult!” — the market wills it. But do those invokingthe will of the market really know what markets want? Again, apparently not.