Matt Stone / The Boston Herald / AP Republican Senator Scott Brown, left, debates Democratic challenger Elizabeth Warren, right, in Lowell, Mass, on Oct. 1, 2012.

If, as David Axelrod once said, “Campaigns are like an MRI for the soul,” then what do we see when we peer into the campaigns of Massachusetts Republican Senator Scott Brown and his challenger, liberal icon Elizabeth Warren? We see a classic culture clash: town vs. gown, the Red Sox vs. the Head of the Charles Regatta, a small-town guy with an iconic pickup truck vs. a Harvard professor who’s a national star.

Brown’s latest ad attacks Warren as if she has been caught in a lie about her racial background: Warren claims to be part Cherokee and Delaware Indian. In her response ad, she says she never benefited professionally from her heritage, a claim backed up by officials who hired her.

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The backstory: Warren says her parents were forced to elope after her father’s family rejected her mother because of her American Indian background. A genealogist said he discovered Warren might be 1/32nd Cherokee but could not produce documents to attest to that. But Brown is certain of what Warren is, and his ad stems from his un-nuanced view of race and her lineage: in the first seconds of their first debate, Brown said, “She claimed that she was a Native American, a person of color, and as you can see, she’s not.” At that moment, Brown might as well have pulled out his race card and slammed it down onto his lectern as if to say, ‘I’m white and I’m proud and I’ll never lie about it!’ He continued hammering at this in their second debate, saying, “She said, ‘I can’t change who I am.’ That’s the nature of her commercials. But up until she was 38, she was white, and then she self-reported and changed her nationality to Native American.”

Brown’s arrogance about his ability to discern a person’s race or ethnicity with total certainty just by using his eyeballs is either extremely impressive or hysterically naive. Many people are racially ambiguous, so his simplistic conception of race does not fit in the age of Obama and shows no comprehension of the complex reality of race. Scientifically, we are all one race.

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“There are no genetic characteristics possessed by all blacks but not by non-blacks,” wrote University of California at Berkeley law professor Ian Haney Lopez in the landmark 1993 essay The Social Construction of Race. “Intragroup differences exceed intergroup differences … The rejection of race in science is now almost complete. In the end we should embrace historian Barbara Fields’s succinct conclusion with respect to the plausibility of biological races: ‘Anyone who continues to believe in race as a physical attribute of individuals despite the now commonplace disclaimers of biologists and geneticists might also believe that Santa Claus, the Easter Bunny and the tooth fairy are real.’ … Social meanings connect our faces to our souls. Race is neither an essence nor an illusion, but rather an ongoing, contradictory, self-reinforcing process subject to the macro forces of social and political struggle and the micro effects of daily decisions.” Lopez concludes: “Race is a social construction.”

Warren has responded to Brown’s simplistic, biology-based line of attack by invoking the social-construct aspect of race. She says being an American Indian is part of her family lore, and she never asked for documentation because who would question family stories? Warren has made her response emotional rather than concrete; race is too messy, too slippery for anything else. She could not prick her finger and provide evidence that she is part American Indian. She may even be privately pleased to see Brown spending his time asserting that the racial earth is flat. It’s already resulted in one embarrassing public misstep, when Brown campaign staffers mimicked American Indian war chants and tomahawk chops in a video that went viral. Brown has since apologized for that.

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Warren has every right to define herself and to do so in a multifaceted way. Racial identity, for mixed Americans, need not be an either/or situation; it can be a both/and. The only way we could truly gauge Warren’s Indian-ness would be to see how much being an American Indian means to her. She says she listed herself in a directory of minority law professors in order to meet “people for whom Native American is part of their heritage and part of their hearts.” Only she knows what place being an American Indian has in her heart.

But if Brown’s “Fauxcohontas” meme were simply about abstract identity claims, it would have minimal resonance. Instead, Brown tries to turn it into something his followers should get really upset about by linking it to affirmative action. In their first debate, he repeatedly asserted that “she checked the box,” meaning that when it came time to apply for a dream job, she, who is visibly (and thus in his mind obviously) not a person of color, pretended to be one. He’s speaking as an aggrieved white man, saying she’s one of those who are taking jobs away from whites unfairly. It’s a way for him to tap into anger that the box is there at all, never able to be checked by white men, a figurative door through which whites cannot pass, robbing them of power.

Here Brown seems to echo the findings of a 2011 study called “Whites See Racism as a Zero-Sum Game That They Are Now Losing” by Michael Norton of Harvard Business School and Samuel Sommers of Tufts. The study found that “whites believe racism against blacks has decreased, which means racism against whites has increased.”

Now, if you or your friends are out of work and think whites are losing the game, then it’s very easy to be angry, but angry politicians often make bad choices, and Brown’s fixation on Warren’s background may be remembered as the campaign detour that cost him his place in the Senate. The question of her ancestry could be a tar baby for Brown. In the Uncle Remus fairy tales, Brer Rabbit encounters a tar baby, a doll made of tar that is meant to trap him. He begins to fight and get stuck, and the more he attacks the doll, the more he gets stuck. Brown is whaling away at Warren’s heritage while dropping in the polls and thus seems to be getting stuck. But whereas Brown rejects entirely the possibility that Warren could have American Indian heritage, I wish she would ask him to prove that he is entirely white.

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