Major League Baseball made do with fallible human umpires for 134 years until this May, when it hit a “rash” or “crisis” or “epidemic” (according to whose account you read) of bad officiating. On consecutive days, umpires misruled on three home runs. In a sport that schedules 2,430 games a year, a few plays will be botched, and none of the bad calls affected a game. But Bud Selig, the commissioner of baseball, was taking no chances. He announced that video replays would be used, starting this week, to check errors by umpires concerning home runs.

“The extraordinary technology that we now have merits the use of instant replay on a very limited basis,” Mr Selig said recently. He insists there will be no spread of electronic umpiring to other corners of the sport. But he may not know his own mind. Once you claim the technology argues for itself, then limiting its application to home runs loses its logic. Mr Selig is on a slippery slope that leads to a reduced human role in umpiring. This might enhance accuracy. It will not be a boon for sport.