“Amerigo Vespucci, who gave his name to America, was a pimp in his youth and a magus in his maturity,” writes Felipe Fernández-Armesto in his new biography (Random House, 231 pages, $24.95). His subject is reminiscent of Melville’s confidence man, a figure of protean energy and inventiveness, a Florentine operator constantly on the make and adept at the makeover. He is a startlingly contemporary personality, and so it is no wonder that the title of this biography puts us all on a first name basis with him.

Part of a n’er-do-well clan, Vespucci got his start working for the Medicis in Florence. Although previous biographers have assumed his early profession as a procurer of women and jewels signaled his close connection with the Medicis, his most recent biographer is skeptical. Lorenzo the Magnificent did not send his best boys to backwaters such as Seville. “Perhaps this is the moment to risk a speculation,” Mr. Fernández-Armesto writes. Amerigo himself may have taken the initiative, desperate to cut loose from a dependent family and make his fortune.

Vespucci emerges in this witty biography as our hero, a picaresque merchant who goes broke backing Columbus’s voyages and then decides to become an explorer himself, setting out in 1499 after his more famous predecessor was generally acknowledged to have failed to make good on his promises: No huge caches of gold, no pathway to Asia, no benign natives, and no paradisal climates.

Amerigo’s two voyages brought him no significant riches but rather a wealth of stories about exotic lands and a whole new continent. So he wrote it all up. Lots of it was hooey, but some of it was based on personal observation. And Amerigo’s reputation as a navigator, acquired through on-the-job training, grew. He put his name on maps, starting with a Florentine publication in 1504 that would go through 23 printings, describing harrowing adventures and miraculous escapes.

Other geographers, thrilled by Amerigo’s accounts, published a huge map in 1507 with his name emblazoned on what is today Brazil. Oops! They soon realized that Vespucci had laid claim to too much. But without CNN and the 24-hour news cycle, it was too late. And so we all became Amerigonians.

Mr. Fernández-Armesto obviously relishes his subject’s prevarications and those gullible followers who made so much of a name. In his retelling, history becomes a bit of a farce when it is not obscured by “romantic illusions.” Even familiar concepts like the Renaissance get a drubbing. Sounding like the Senator Ted Stevens of biography, Mr. Fernández-Armesto shouts:

“It inaugurated modern times.” No: Every generation has its own modernity, which grows out of the whole of the past. “It was revolutionary.” No: Scholarship has detected half a dozen prior renaissances. … “It was art for art’s sake.” No: It was manipulated by plutocrats and politicians.

And there is much more to the list of no’s in this iconoclastic, irreverent, but also superbly researched portrayal of a subject gifted at getting history to take him at his word.

We live in a country named by mistake. But to get the joke, you have to accept this biographer’s shrewd research.

crollyson@nysun.com