Ithaca, N.Y.

ADAM SMITH’S most enthusiastic modern disciples insist that the recipe for economic progress is to push government aside and let unfettered markets work their magic. His invisible hand theory does provide a tidy account of how market incentives can generate enormous wealth. But as Charles Darwin saw so clearly, unbridled competition doesn’t always promote the common good.

It’s not how fast or how strong you are that matters, but whether you’re faster or stronger than your closest rivals. The arms races that result when rivals jockey for position — witness the huge antlers of bull elk — often spawn considerable waste. And as with the elk, so, too, in the marketplace. The start time for post-Thanksgiving sales is a vivid case in point.

In recent years, large retail chains have been competing to be the first to open their doors on Black Friday. The race is driven by the theory that stores with the earliest start time capture the most buyers and make the most sales. For many years, stores opened at a reasonable hour. Then, some started opening at 5 a.m., prompting complaints from employees about having to go to sleep early on Thanksgiving and miss out on time with their families. But retailers ignored those complaints, because their earlier start time proved so successful in luring customers away from rival outlets.

Those rivals, of course, didn’t sit idly by. Their inevitable response was to open earlier themselves, restoring competitive balance. Other retailers began opening at 4 a.m., then 3 a.m., and, eventually, at midnight. Several malls have promoted “Moonlight Madness.” Last year Toys “R” Us opened at 10 p.m. on Thanksgiving. This year, Wal-Mart will do the same. The costs to store owners and their employees and families are enormous: millions must now spend time away from home on the one occasion that all Americans, regardless of religion or cultural background, share as a family holiday.