Biden’s calm and steady acceptance caps a unifying Democratic convention

In accepting the Democratic presidential nomination, Joe Biden decisively debunked the accusation by President Trump that he is “sleepy” or mentally impaired. His speech may not have been soaring oratory, but it was a self-assured and sobering address. It combined a withering indictment of the man he referred to disdainfully as “the current occupant of the White House” with a promise to “choose hope over fear, facts over fiction, fairness over privilege.”

Biden’s overarching emphasis was on the urgency of replacing a president who has “cloaked America in darkness for...