On the left today, most people seem to think that science is trustworthy and deserves autonomy and influence. The Bush Administration must be a bunch of rubes, because they continually get into struggles with scientists. Thus, for example, the first masthead editorial in today’s New York Times is entitled “Science at Risk.” The Times says:

As written in 1970, the [Clean Air Act] imposes one overriding obligation on the E.P.A. administrator: to establish air quality standards “requisite to protect the public health” with “an adequate margin of safety.” Economic considerations–costs and benefits–can be taken into account in figuring out a reasonable timetable for achieving the standards. But only science can shape the standards themselves.

Congress wrote the law this way because it believed that air quality standards must be based on rigorous scientific study alone and that science would be the sure loser unless insulated from special interests.

But the definitions of “requisite to protect the public health” and an “adequate margin of safety” could never be scientific. These were always value-judgments–implicit decisions about how to balance mortality and morbidity versus employment and productivity. Costs always factored in, because the only level of emissions that would cause no harm to human health is zero. EPA has allowed enormous quantities of emissions into the air, surely because the agency balances moral goods against moral evils. What the Clean Air Act said was: professional scientists (not politicians or judges) shall estimate the costs of pollution. Since it is unseemly to talk about human deaths and sickness as “costs,” scientists shall not use this word, nor set explicit dollar values on lives. Instead, they shall declare certain levels of safety to be “adequate,” and present this as a scientific fact.

I well remember when people on the left were the quickest to be skeptical of such claims. Science is frequently an ally of industry and the military. It is intellectually imperialistic, insensitive to cultural traditions. It is arrogant, substituting expertise for public judgment even when there are no legitimate expert answers to crucial questions. (For instance, What is the economic value of a life?). Science is a human institution, driven by moral and cultural norms, power, and status. It is not an alternative to politics.

So progressives used to say. Yet scientific consensus now seems to favor progressive views of key issues such as climate change. The conservative coalition encompasses critics of science, such as creationists. And, as Richard Lewontin wrote immediately before the 2004 election, “Most scientists are, at a minimum, liberals, although it is by no means obvious why this should be so. Despite the fact that all of the molecular biologists of my acquaintance are shareholders in or advisers to biotechnology firms, the chief political controversy in the scientific community seems to be whether it is wise to vote for Ralph Nader this time.”

These are short-term political calculations that lead progressives to ally themselves with science and endorse its strongest claims to power. If we are going to defend science, we should do so on the basis of principle, not political calculation. I agree with the Times that the EPA should clamp down on air pollution. I disagree that this would represent a triumph of science over politics. It would be a moral and political victory–and that is all.

Moral relativism is the idea that there isn’t any objective or knowable right or wrong; there are only the opinions of individuals or cultures at particular times in history. Some famous conservatives have made their names by attacking moral relativism: Bill Bennett and Allan Bloom, for instance. Many of us also object to it from the left, since it undermines claims about social justice. But conservatives and liberals sometimes make moral-relativist arguments when it suits them.

Consider Justices Roberts and Thomas in the case of Parents Involved in Community Schools v. Seattle School District (2007). This is racial segregation/integration case. Defendants want to use race as a factor in assigning kids to schools, for the purpose of increasing diversity or integration. They claim that this goal is benign, unlike segregationists’ use of race, which was malicious. They ask the court to allow racially conscious policies that are well-intentioned, reasonably supported by evidence, and enacted through democratic procedures.

In response, Justice Roberts quotes Justice O’Connor from an earlier case: “The Court’s emphasis on ‘benign racial classifications’ suggests confidence in its ability to distinguish good from harmful governmental uses of racial criteria. History should teach greater humility… . ‘[B]enign’ carries with it no independent meaning, but reflects only acceptance of the current generation’s conclusion that a politically acceptable burden, imposed on particular citizens on the basis of race, is reasonable.” Justice Thomas likewise argues that allowing a school system to promote diversity through racial classification means acceding to “current societal practice and expectations.” That was the approach, he argues, that led the majority in Plessy v Ferguson to uphold Jim Crow laws, which were the fad of that time. “How does one tell when a racial classification is invidious? The segregationists in Brown argued that their racial classifications were benign, not invidious. … It is the height of arrogance for Members of this Court to assert blindly that their motives are better than others.”

These justices doubt that there is a knowable difference between benign and invidious uses of race. But surely there are moral differences between Seattle’s integrationist policy of 2005 and the policy of Mississippi in 1940: differences of intent, principle, means, ends, expressive meaning, and consequences or outcomes. If we cannot tell the difference, we are moral idiots. There can be no progress, and there isn’t any point in reasoning about moral issues.

To be sure, Seattle’s policy is open to critique. The conservative justices quote some politically correct passages from the school district’s website to good satirical effect, and the policy could also be attacked from the left. Whether Seattle should be able to decide on its use of race, or whether that should be decided by judges, is a good and difficult question. But it’s almost nihilistic to assert that “benign” has “no independent meaning” and reflects only the opinions of the “current generation.” That equates Seattle’s policy with that of, say, George C. Wallace when he “barred the schoolhouse door.”