Why did anyone think Joe Biden was ready for a 90-minute presidential debate? One reason is that a small handful of journalists, with left-leaning sympathies but very credible records, have interviewed him and those close to him in the White House and returned with reports that while he’s definitely older, he’s still pretty sharp and in charge.

Two of the most prominent are Biden biographers Evan Osnos and Franklin Foer. I spoke to them Sunday as they reconciled their own portrayals with the faltering 81-year-old they saw on national television.

In his deeply-reported recent New Yorker article, Osnos detailed Biden on the precipice of his final campaign, the definition of an elder statesman steeling himself for a rematch with an emboldened Donald Trump. But in his one sitdown with Biden in January (the White House declined his invitation for a second), he described an older Biden in command of his faculties: “His voice is thin and clotted, and his gestures have slowed, but, in our conversation, his mind seemed unchanged. He never bungled a name or a date.”