By now, education observers are aware of New York City mayor Bill de Blasio’s incursion on the Big Apple’s charter sector.

No one should be surprised; this was no ambuscade, no lying in wait. He publicly campaigned against charters. He actually called his predecessor’s policy of allowing charter public schools to share public-school space with district public schools “abhorrent.”

This has been a shame for low-income kids, of course, given NYC’s charters’ superb performance. But it has made for 24-karat media fodder.

Hizzoner has picked a fight with Eva Moskowitz, not only the operator of a network of tremendously successful charters but also one of the toughest pugilists in the city’s notoriously combative political squared-circle. The Democratic mayor is now involved in internecine warfare over charters with the state’s Democratic governor, Andrew Cuomo, who publicly declared, “We will save charter schools.”

But de Blasio’s camp hasn’t turned tail; they’ve trickily tergiversated. Despite their words and deeds, the mayor’s camp is claiming he’s not really against charters—his narrative got hijacked. He likes charters just fine!

Former governor Mario Cuomo, Andrew’s father, brilliantly said, “You campaign in poetry. You govern in prose.”

Given the mayor’s attempt at playing both sides, his team might be credited with implying a third part of the equation: “You spin in prevarication.”

Though all of this makes for Broadway-ready pyrotechnics, there is an important and as-of-yet unexplored element of this script.

According to a Wall Street Journal column, Mr. de Blasio recently explained his charter animus in a radio interview:

There is a “strong private-sector element” in their funding, (de Blasio) said. The mayor agreed with host Ebro Darden that “a lot” of charter schools are funded by big business: “Oh yeah, a lot of them are funded by very wealthy Wall Street folks and others.”

So let’s put the question squarely: what is the proper role of private money in public education?

One could infer from the mayor’s comments that private money and public schooling should not mix, especially if that money comes from “very wealthy Wall Street folks.”

If that’s the case, then why is the mayor’s chancellor of schools, Carmen Fariña, the board chair of the Fund for Public Schools, whose express legal purpose is “improving New York City’s Public Schools by attracting private investment” in public education?

Moreover, its board of directors is filled with, well, very wealthy Wall Street folks, including a managing director of Goldman Sachs. The Fund is evidently proud of this; it points out that the board has an “impressive group of New York City’s business and philanthropic leaders.”

If you look at the Fund’s “990” tax form, you’ll find even more reason to question the veracity of the mayor’s concern about the malign influence of private money in public schools.

The tax document describes as “critical” the private contributions provided by the Fund.

According to the most recently released filing, the Fund brought in about $50 million. It had $33 million invested in publicly traded securities (Wall Street!).

And it had but one grantee: the New York City Department of Education at $35 million.

The tax form lists 11 donations of over $1 million apiece, the highest at $14.3 million. (Unfortunately, none of these contributors are named.)

If the mayor were truly concerned about “corporate” funding of public schools, we have to ask, “Does that include all corporate money?”

Andrew Carnegie made his millions as the owner of the world’s largest steel corporation. The foundation in which he invested his fortune has given at least seven grants totaling $8.5 million to the Fund for Public Schools in the last five years.

The Ford Motor Company was at one time among the most profitable corporations in the world and today remains one of the largest automakers. The Ford Foundation, into which much of this largesse was poured, has given the Fund for Public Schools at least four grants totaling $2.5 million in the last five years.

John D. Rockefeller was one of the most successful industrialists in American history, amassing a fortune that peaked at nearly $1 billion. He established a foundation in 1913. This philanthropy has invested in public education in the Big Apple schools in countless ways, including recently in green-career training and scholarships for students protecting the environment.

I deeply admire affluent individuals who give away gargantuan sums of money for the public good, especially to K–12 education. Mr. Carnegie wanted his estate to do “real and permanent good in this world” and create “ladders on which the aspiring can rise.”

Rockefeller once wrote, “The time will come when men of wealth will more generally be willing to use it for the good of others.” Since then, his foundation has given away more than $14 billion.

These facts raise several important and potentially uncomfortable questions for Mayor de Blasio.

Do you believe that the wealthy should be able to give to charitable causes of their choosing?

Do you believe that such private money should be used to supplement public funds that support public schools?

If yes, then why do you begrudge private donations to charters?

If no, then will you bring to an end private contributions—like those made by the Fund for Public Schools and the Carnegie, Ford, and Rockefeller foundations—to the school district of New York City?