Sometime in the new millennium, “global warming” evolved into “climate change.” Amid growing controversies over the planet’s past temperatures, Al Gore and other activists understood that human-induced “climate change” could better explain almost any weather extremity – droughts or floods, too much heat or cold, hurricanes and tornadoes.

Similar verbal gymnastics have gradually turned “affirmative action” into “diversity” – a word ambiguous enough to avoid the innate contradictions of a liberal society affirming illiberal racial preferencing.

In an increasingly multiracial society, it has grown hard to determine the racial ancestry of millions of minorities. Is someone who is ostensibly one-half Native American or African-American classified as a minority eligible for special consideration in hiring or college admission, while someone one-quarter or one-eighth is not? How exactly does affirmative action adjudicate our precise ethnic identities these days? These are not illiberal questions – given Massachusetts Sen. Elizabeth Warren’s past claims of being Native American to find advantage in her academic career.

Aside from the increasing difficulty of determining the ancestry of multiracial, multiethnic and intermarried Americans, what exactly is the justification for affirmative action’s ethnic preferences in hiring or admission – historical grievance, current underrepresentation due to discrimination, or both?

Are the children of President Barack Obama or Attorney General Eric Holder more in need of help than the offspring of first-generation immigrants from the Punjab or Cambodia? If non-white ancestry no longer offers an accurate assessment of ongoing discrimination, is affirmative action justified by a legacy of historical bias or contemporary ethnic underrepresentation?

Does a recent arrival from Oaxaca who fled the racism and poverty of Mexico warrant special compensation upon arrival in the United States? And if so, when? A day, a month, a year or a decade after crossing the border? How about a Chilean, Korean or Iraqi immigrant? Should particular coveted employment match the nation’s racial composition – jobs on the faculty, but not jobs in the NBA or in the Postal Service?

How do we fairly allocate compensation for past collective sins against a bygone generation? Slavery, Jim Crow, internment of Japanese-Americans, racially exclusionary immigration laws and the denial of U.S. admission to Jews fleeing the Holocaust: All were reprehensible; but it is difficult to know the degree to which these injustices still distort the career paths of individual Americans, or who still alive is to blame.

In 2009, the University of California system changed its admissions policy allegedly to curtail admission to Asian-Americans. Such anti-affirmative action arose not because UC was a racist institution, but because as an applicant group, Asian-Americans were outperforming most other ethnic groups, in numbers disproportionate to the general population.

In other words, in the manner that the Ivy League turned away qualified Jews in the 1920s and ‘30s, so some university administrators apparently thought that engineering a campus “to look like America” was more important than simply admitting those with the strongest academic achievement.

Affirmative action – fossilized for a half-century – also made few allowances for class. Asian-Americans, for example, have higher per-capita incomes than Americans as a whole. Were affluent minority individuals eligible for affirmative action?

Will the children of multimillionaire Tiger Woods – or of Jay-Z and Beyoncé – qualify for special consideration on the theory that statistical underrepresentation in some fields or racial pedigrees will make their lives more challenging than the lives of poor white children in rural Pennsylvania or first-generation Arab-Americans in Dearborn, Mich.?

If ossified racial preferences don’t work in 21st century multiracial America, then the generalized idea of “diversity” – just picking and choosing people without any rationale other than ensuring lots of different races and ethnic groups – offers a better defense of extending preferences in lieu of strictly meritocratic criteria.

Yet diversity no more alleviates the problem of bias than does climate change end controversy over global warming. We really do not mean “diversity” in the widest sense of the word. No Ivy League law school is worried that its faculty profile is disproportionately 90 percent liberal, or lacks fundamentalist Christians commensurate with their numbers in the general population.

The idea of diversity, racial and otherwise, is deeply embedded in politics. President George H.W. Bush was not especially lauded for appointing an African-American Supreme Court justice, Clarence Thomas, apparently because Thomas was considered conservative. Liberal Attorney General Eric Holder was seen by the media as a genuinely diverse appointment in a way that a conservative predecessor, Alberto Gonzales, was not.

Like Prohibition, affirmative action and then diversity were originally noble efforts that were doomed – largely by their own illiberal contradictions of using present and future racial discrimination to atone for past racial discrimination.

It is well past time to move on and to see people as just people.

© 2013 TRIBUNE MEDIA SERVICES, INC.