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The seemingly obvious implication is that a candidate who wins without enthusiasm is doomed, that a candidate who inspires is a better electoral bet than one who has simply endured. Find a candidate who can trigger turnout among the most reliable Democratic voters, the argument goes, and the party will have a much better chance than trying to beckon back disaffected Democrats with a safe, familiar face who may not be magnetic but who will not repel. That’s what Sanders means when he talks of a political “revolution” that will sweep his ambitious economic program into law. That’s what Elizabeth Warren argues when she inveighs against cautious incrementalism. And didn’t the past two Democrats (as well as the current president) take the White House by challenging and defeating the safer, more familiar choices?

There is, however, another side to this argument—a category of underappreciated “defaults” who can win. And there’s a good chance Biden belongs in this second group.

Harry Truman came into 1948 so unpopular that many Democrats looked hard for an alternative (one appealing possibility: Dwight Eisenhower, who had not yet declared himself a Republican). Sure, Truman was an incumbent president, but he wasn’t elected to the office and had to prove he could win a presidential campaign. Few believed him when he declared, in a post-midnight acceptance speech, that “Senator Barkley and I will win this election and make these Republicans like it—don’t you forget that!” But, as America and The Chicago Tribune learned, he did.