Economists like to think of themselves as mathematicians — or, if feeling momentarily humbler, as physicists. This year’s winners of the Nobel Prize in economics, however, seem to conceive of themselves more as engineers. Like Alvin Roth and Lloyd Shapley, who won the prize in 2012, Paul Milgrom and Robert B. Wilson are specialists in “market design,” a field which, as Roth wrote in a famous paper, calls for “an engineering approach.”
Roth argued that market designers should take bridge-builders as their exemplars: “Engineering is often less elegant than the simple underlying physics, but it allows bridges designed on the same

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