A world of difference separates President Biden’s nominee for secretary of education from the previous secretary, Betsy DeVos. DeVos infamously proved herself unaware of and even largely uninterested in the realities of public education. Miguel Cardona, who is expected to be confirmed by the Senate on Wednesday, was a public school student, teacher, principal, assistant superintendent and state-level education leader. His children attend public school. He lives and breathes the challenges and opportunities of public education.

Yet in one vital aspect, the two leaders agree, and their agreement is part of the reason that public schools have never lived up to Americans’ inflated expectations.

Even though DeVos never was a firm supporter of public schools, she never doubted the importance of education policy. As she put it in late 2020, education policy “will either break our already fragile economy, or it will unleash an age of achievement and prosperity the likes of which we’ve never seen.”

Cardona agrees that education policy should be front and center in the United States. In his speech accepting his nomination by Biden, for example, he noted that public education can serve as the “great equalizer.” While it doesn’t always succeed, good education policy can make public schools authentic “places of innovation” that have the power to heal the country’s social and economic woes. In Cardona’s eyes, education can solve the problems that bedevil cities, allow low-income Americans to move up and even bridge the racial divide.

Cardona and DeVos are not unique in this regard. By telling people what they want to hear — that we can solve social problems quickly and cheaply through school reform — leaders have long derailed attempts to address the complex causes of social inequality. Even if they do not intend to, leaders who promise too much for school reform end up downplaying the true difficulties of improving society.

The pattern is as old as public education itself. The roots of public education in the United States, at least in larger cities, lie in the first decades of the 1800s. City leaders were aghast at the crowds of children left out of the limited number of tuition-free schools. Cities such as New York, Philadelphia and Baltimore had not yet begun the explosive growth they would experience beginning in the 1840s, but the elite at the time were already alarmed at the numbers of children in the streets.

In New York, for example, philanthropists warned in 1814 about the “large number of children” left merely “wandering the streets.” Similarly, Baltimore’s well-heeled reformers worried about “the growing numbers of disruptive elements in the population.”

Like Cardona and DeVos, leaders in the early 1800s assumed that public school reform would solve the problem. As New York’s Mayor De Witt Clinton explained in 1809, for too long the “humble and depressed” had not received the benefits of school. Clinton embraced a new kind of school, one in which advanced students taught younger ones. Without needing to pay costly teacher salaries, cities could afford to create new free schools for all the children who needed them.

This reform, Clinton believed, would do more than incrementally improve life for some children. By improving public schooling, Clinton said, New York was “creating a new aera [sic] in education.” His reform would “redeem the poor and distressed of this world from the power and dominion of ignorance.” Other reformers at the time agreed. In 1817, Philadelphia’s school leaders promised that their similar school reform was “destined to usher in the millennial day.”

Like Clinton, the enthusiastic elite in Philadelphia and other cities imagined that they were doing more than merely improving instruction. They believed their school reform would solve the age-old problems of poverty and crime, unleashing “an age of achievement and prosperity the likes of which we’ve never seen.”

But these assumptions were flawed. Even after ambitious school reforms, urban poverty did not disappear. Nor did changing the way public schools operated eliminate the deep divisions that separated Americans. Without trained teachers, the new schools did not deliver high-quality education to the poor. As one African American editor complained in 1827, the free schools had only “dull and stupid instructers” [sic] and students were not learning even basic literacy skills.

Reformers’ mistakes were more than mere lamentable naivete. They established a harmful pattern that lingers to this day. Namely, politicians harm the chances of finding real solutions to social problems by making unrealistic promises about schools.

In the 20th century, even the most momentous successes in school reform have only proved their own limitations. In 1954, for example, the Supreme Court ruled that racial segregation in schooling unconstitutional. Reformers promised an end to racism as a whole. Yet, grimly, school segregation today is increasing in many cities. Similarly, as part of the “War on Poverty,” the 1965 Elementary and Secondary Education Act promised a new day, with Title I schools fighting poverty and improving opportunity. Yet today, though there have been great successes, even more children live in poverty than when the act was signed.

In each case, improving schools was a helpful start, but it was too often taken as a happy conclusion. Instead of beginning the effort to fight racism or poverty, these reforms were seen as the end of the effort, and attention was diverted elsewhere.

This doesn't mean programs using public schools to fight poverty and racism are bad. In fact, they often do much good. But too often, politicians make extravagant promises that sidetrack conversations about the true causes of social problems. Too often, by endorsing flawed assumptions that better schools can heal every problem, reformers have shifted attention and funding away from programs that address the roots of social divisions.

Moreover, making unrealistic promises may be good politics, but it has always been terrible policy. School reform need not end poverty or eliminate racism to be worthwhile. By raising unrealistic expectations, extravagant promises about school reform breed cynicism and disillusionment — and lead to the conclusion that programs have failed, when in reality that is far from the truth.

History teaches that though schools can be part of a solution to racism and poverty, they can’t solve the problems themselves. Too often, leaders have imagined that they could use schools as levers to lift the rest of society. But schools are not outside of society. For good or ill, schools are society, with all its embedded flaws and inequalities. Whether Democratic or Republican, history shows that promises to the contrary are destined to fail.