[Jonathan Zimmerman teaches history and education at New York University and is the author of the just-published "Small Wonder: The Little Red Schoolhouse in History and Memory."]

Here's a good argument for putting Sonia Sotomayor on the Supreme Court: She's knowledgeable, respected and deeply experienced. As a federal judge for nearly two decades, she's heard thousands of cases and written hundreds of opinions.

And here's a lousy argument for confirming Sotomayor: She would be the first "Hispanic" on the court.

I put the term in quotation marks because it's a recent invention, dating to the 1970s and '80s. Before then, when Sotomayor was growing up with her Puerto Rican family in New York City, she was not Hispanic.

And words make a difference. As many commentators have reminded us since President Obama nominated Sotomayor, judges are inevitably shaped by their life experiences. But these experiences are themselves shaped -- and, sometimes, distorted -- by the terms that we use to describe them.

How did Mexicans, Cubans, Puerto Ricans, Dominicans, Salvadorans, Panamanians, Nicaraguans and Guatemalans all become Hispanic?

Amid the African American civil rights struggle of the 1960s, many of these groups joined hands to demand voting rights, bilingual education and social services. Here they received a big assist from an unlikely source: Richard Nixon. Eager to bring Mexicans and other Latino immigrants into the Republican fold, Nixon also saw them as a potential bulwark against black political aspirations.

"All Spanish-speaking Americans share certain characteristics -- a strong family structure, deep ties to the church, which makes them open to an appeal from us," wrote one GOP campaign strategist on the eve of Nixon's 1972 presidential reelection bid. "The Democratic Party is under suspicion for favoring politically potent blacks at the expense of the needs of Spanish-speaking people."

So Nixon threw his weight behind bilingual education, which has since become a bête noire for the GOP. He also ordered the Census Bureau to add a query on its 1970 form asking whether respondents were "Hispanic," hoping to further solidify this new voting bloc.

Census Bureau officials balked, noting -- correctly -- that the term lacked scientific and historical precision. They also worried that respondents wouldn't recognize it. So the most commonly used census form in 1970 asked respondents if they were of "Spanish" origin, not whether they were Hispanic.

All that would change in 1977, when the Office of Management and Budget instructed federal agencies to classify Americans as one of four races -- white, black, American Indian/Alaskan Native or Asian/Pacific Islander -- and also to distinguish between two ethnic categories, "of Hispanic origin" and "not of Hispanic origin." Since then, the census has asked people their race and whether they're Hispanic, which is not listed as a "race" per se.

Increasingly, however, Americans thought of it as such. Government agencies used "Hispanic" alongside "Asian" and "black," making Hispanic into a de facto racial category. Businesses and educational institutions counted Hispanics -- or, sometimes, "Latinos" -- as a race in diversity and affirmative action reports.

Not surprisingly, then, Hispanics became more likely over time to identify themselves as a separate race too. In the mid-1990s, 60% of the respondents to a study of more than 5,000 Latin American immigrants self-identified as "white," for example, but only 20% of their children did so.

That's an unprecedented development, as the United States had continuously absorbed people formerly identified in the census as from nonwhite races into the white majority. Jews, Italians and Slavs were all once classified as separate races; now, they're white. But Hispanics are moving in the opposite direction -- from white to nonwhite. In our minds, at least, they've become a minority race.

The language of race is a unifying one, blinding us to the irreducible diversity that a single category can contain. Consider Sotomayor's now infamous comment that a "wise Latina woman" would render a better judicial decision than a white male. While GOP antagonists accused Sotomayor of reverse racism and Democrats rushed to her defense, nobody pointed out that wise Latina women come in all shapes, sizes and ideologies. Would a wise Cuban woman in South Florida see eye-to-eye with a wise Mexican woman in San Diego, or with a wise Salvadoran woman in Washington, D.C.? Probably not.

Even worse, the idea of race tricks us into seeing "Hispanic" as a biological category rather than a cultural one. I frequently do an exercise with my students, asking them how a scientist would identify their race. The most common reply is also the most troubling one: via a blood test. In fact, that would tell you the opposite: We all come from the same ancestor, in East Africa, and we're all mongrels. The blood test does not identify your "race," which primarily exists only in our minds.

As a child, Sotomayor was probably classified as white; now she's Hispanic. But her DNA is the same. The only thing that has changed is the way we look at her. Belying every shard of evidence, we continue to believe that races are different under the skin.

So let's hope that the Senate confirms Sotomayor, one of the most qualified nominees in the history of the Supreme Court. Then let's welcome her as the first person of Puerto Rican descent on the court, not as the first "Hispanic."

If you think the words don't matter, you haven't been listening.