With retailers' Black Friday arms race spilling over into Thanksgiving Day, everybody might be better off with a dose of detente.

It was bad enough last year, when Wal-Mart offered "door-buster" deals on toys starting at 10 p.m. on Thanksgiving, and several other stores, including Macy's and Best Buy, opened at midnight. This year Sears is joining the fray, opening up at 8 p.m. on Thanksgiving. Target is opening up at 9 p.m. And so it goes.

Retailers,...