Let’s say it straight: Every Georgia Republican who votes for former Sen. David Perdue in next year’s gubernatorial primary is voting to strangle American democracy and replace it with an arrangement in which elections can be overturned on a whim, just because somebody says so. There is no other rationale for Perdue’s candidacy, no other reason for him to have launched a campaign against an incumbent governor of his own party. That, and to try to placate the implacable Donald Trump. That incumbent, Brian Kemp, has served for almost 20 years as a Republican state senator, a Republican secretary of...