When Rand Paul launches his campaign for President today, in a speech in Louisville, he is unlikely to talk about serving as an Army general or, for that matter, saving the lives of Naval officers in the South Pacific. Nor will he speak of publishing a newspaper, leading one of the nation’s most prestigious universities, or directing the C.I.A. That, of course, is because he’s done none of these things; these were the qualifications of candidates in previous Presidential elections. What Rand Paul actually did in the years before 2011, when he took office as the junior senator from Kentucky, was to work as an ophthalmologist and to moonlight, in the off-hours, as an anti-tax activist.

Is this enough to qualify him for the Presidency? Or is that question hopelessly beside the point to the Republican voters who are considering carrying his banner? Whatever Paul’s liabilities might be in the battle for his party’s nomination, his lack of experience does not appear to be one of them. He is, after all, hardly alone; the field is full of neophytes. Other than Jeb Bush, not one of the serious Republican contenders played a meaningful role in our national life before 2010, the year that Paul and Marco Rubio—who will announce his own candidacy next week in Miami—ran for the Senate. Scott Walker was elected governor of Wisconsin that same year. Ted Cruz has been in the Senate only since 2013—though it seems longer, because he hasn’t stopped talking since he got there.

Sifting through these candidates’ speeches, one finds few indications of past experience—little use, even, of the past tense. To the extent that they have anything to say about their own lives, it concerns, in most cases, their childhoods. They stress, in practiced fashion, their modest roots. Rubio describes himself as the “son of a bartender and a woman who worked in a hotel.” Walker tells audiences that he is the “son of a small-town preacher and a mom who was a part-time secretary.” (In the opening passage of his budget address in February, he offered even humbler detail: “Mom was raised on a farm where they didn’t have indoor plumbing.”) Cruz, meanwhile, dedicated the first six minutes of his announcement speech last month to stories about his parents’ struggles, and said more about them than he did about himself.

Paul’s upbringing, by contrast, is double-edged. His father, Ron Paul, is, of course, an icon of the libertarian right, which confers, on the son, a certain kind of credibility—just not the hard-won, hardscrabble kind that candidates since Andrew Jackson have sought. At the Conservative Political Action Conference, in February, Rand Paul allowed a bit opaquely that “I was born into the America that experiences and believes in opportunity.” (If you thought he was from the America that doesn’t believe in opportunity, you were wrong.) He has had little else to say about his life, or life’s work, prior to his decision that it merits his leading the free world. The aptness of ophthalmology as a metaphor for national leadership (“I see a great nation,” as F.D.R. said) remains, at this point, unexploited. ...