IF THE history of American populism teaches anything, it is the importance of addressing the legitimate concerns of the lower and middle classes without engaging in illegitimate vilification of the well-to-do or anyone else. From Andrew Jackson to Huey Long, populists have given voice to the voiceless — but also have played on prejudice, stereotypes and resentment.

That is the lens through which to view the current flap over President Obama’s choice of Antonio Weiss to serve as undersecretary of Treasury for domestic finance, a senior position with broad responsibility over financial institutions, the federal debt, regulation and capital markets. The 48-year-old Mr. Weiss would bring much in the way of relevant experience to the job, having graduated from Harvard Business School and gone on to a successful career in finance, most recently as head of investment banking for the venerable Lazard firm. If there’s anything anomalous on paper about this appointment, it might be the fact that Mr. Obama has chosen a veteran of eight years in Lazard’s Paris office for a domestic finance job.

That is not the main concern of Mr. Weiss’s detractors within the populist wing of the Democratic Party, though. Led by Sen. Elizabeth Warren (D-Mass.), they criticize the symbolism of Mr. Weiss’s nomination, which, according to Ms. Warren, “tells people that whatever goes wrong in this economy, the Wall Street banks will be protected first.” Mr. Weiss stands accused of having played an advisory role in the recent merger between Burger King and the Canadian company Tim Hortons — a “tax inversion” deal allegedly driven by Burger King’s desire to escape U.S. corporate levies.

To be sure, Mr. Weiss has reported assets of between $54 million and $203 million, and he has given tens of thousands of dollars to Mr. Obama’s campaigns while persuading others to give much more. This confirms that he, like other Obama nominees — say, Commerce Secretary Penny Pritzker — is wealthy and politically connected. Whether any of that or his advisory role in the Burger King deal should disqualify him is a very different question. To the extent we know anything about Mr. Weiss’s actual policy views, they seem consonant with Ms. Warren’s. For example, he is a co-author of a Center for American Progress tax reform paper that called for a more progressive system and $1.8 trillion in tax increases on upper-income Americans over 10 years.

The populists’ case against Mr. Weiss so far amounts to a grab-bag of symbolism and epithets, not a rationale. Nothing in his record suggests that his nomination is less than ordinarily worthy of the deference the Senate owes, or ought to owe, the president when staffing an administration. At the very least, Mr. Weiss deserves a fair hearing, in which he can publicly respond to the accusations against him, such as they are.

If his critics are genuinely interested in judging him as an individual, rather than as a purported representative of a predatory class, a fair hearing is what they’ll give him. Anything less would be populism at its irrational worst.