A fight has broken out in the blogosphere over whether Team Blue or Team Red is more "anti-science." Microbiologist Alex Berezow, editor of RealClearScience, struck the first blow in the pages of USA Today. "For every anti-science Republican that exists," he wrote, "there is at least one anti-science Democrat. Neither party has a monopoly on scientific illiteracy."

The battle of the blogs was joined when Chris Mooney, author of The Republican War on Science, denounced Berezow's column as "classic false equivalence on political abuse of science," over at the Climate Progress blog at the Center for American Progress. He accused Berezow of trying "to show that liberals do the same thing" by "finding a few relatively fringe things that some progressives cling to that might be labeled anti-scientific."

Berezow acknowledged that a lot prominent Republican politicians including—would-be presidential candidates—deny biological evolution, are skeptical of the scientific consensus on man-made global warming, and oppose research using human embryonic stem cells. As evidence for Democratic anti-science intransigence, Berezow argued that progressives tend to be more anti-vaccine, anti-biotechnology when it comes to food, anti-biomedical research involving tests on animals, and anti-nuclear power.

In support of his claims, Berezow cited some polling data from a 2009 survey done by the Pew Research Center for the People and the Press. In fact that survey identified a number of partisan divides on scientific questions. On biological evolution, the survey reported that 97 percent of scientists agree that living things, including human beings, evolved over time and that 87 percent of them think that this was an entirely natural process not guided by a supreme being. Some 36 percent of Democrats believe that humans naturally evolved; 22 percent believe that evolution was guided by a supreme being; and 30 percent don't believe humans have evolved over time. The corresponding figures for Republicans are 23 percent, 26 percent, and 39 percent, respectively.

On climate change, the Pew survey reported that 84 percent of scientists believe that the recent warming is the result of human activity. Among Democrats, 64 percent responded that the Earth is getting warming mostly due to human activity, whereas only 30 percent of Republicans thought so. That is truly a deep divide on this scientific issue.

The Pew survey next asked about federal funding of human embryonic stem cell research. Democrats favored such funding by 71 percent compared to only 38 percent among Republicans. The Republican response is likely tied to two issues here: (1) the belief that embryos have the same moral status as adult people; and (2) less general support for spending taxpayer dollars on research. With regard to the latter, the Pew survey reports that 48 percent of conservative Republicans believe that private investment in research is enough, whereas 44 percent believe government "investment" in research is essential. As Mooney might say, the partisan differences over stem cell research might be considered a "science-related policy disagreement" that should not be "confused with cases of science rejection."

But what about Berezow's examples of alleged left-wing anti-science? Mooney's basic response is that some groups on the left are in fact anti-science with regard to those issues, but he asserts that they are fringe groups with no power, unlike the Tea Party activists who are driving Republican politics. For example, Mooney argues that PETA (People for the Ethical Treatment of Animals) "is not a liberal group commanding wide assent for its views on the left, doesn't drive mainstream Democratic policy, etc." Fair enough. But the Pew survey does report that Democrats are split right down the middle on using animals in scientific research, with 48 percent opposing it and 48 percent favoring it. Republicans divide up 62 percent in favor and 33 percent opposed. Like stem cells, using animals in research is often framed as a moral issue.

With regard to nuclear power, the Pew survey found 70 percent of scientists in favor of building more nuclear power plants. For their part, 62 percent of Republicans favored more nuclear power plants, compared to 45 percent of Democrats. This difference is likely related to views on nuclear safety. For instance, a 2009 Gallup poll reported that while 73 percent of Republicans are confident in the safety of nuclear power plants, only 46 percent of Democrats agree.

Climate Progress blogger Joe Romm chimed in to Mooney's column, arguing that the nuclear power industry was done in by commercial considerations rather than leftwing opposition. And that's true because coal and gas-fired electricity generation plants are considerably cheaper to build. However, if policies limiting the emissions of greenhouse gases produced by burning fossil fuels are adopted, nuclear becomes more commercially attractive. In fact, much more attractive than the solar power alternatives pushed by Democrats like Romm. But that is not a scientific argument; it's an economic one.

What about partisan attitudes toward genetically enhanced crops and animals? A 2006 survey [PDF] by the Pew Trusts found that 48 percent of Republicans believe that biotech foods are safe compared to 28 percent who did not. Democrats at 42 percent are just slightly less likely to think biotech foods are safe while 29 percent think they are not. Back in 2004, the National Academy of Sciences (NAS) issued a report on the safety of biotech crops that noted: "To date, no adverse health effects attributed to genetic engineering have been documented in the human population." That is still the case today. In 2010, the NAS issued another report that found that biotech crops offer substantial environmental and economic benefits.

Mooney in his response to Berezow allows with regard to genetically enhanced crops and animals that "there's some progressive resistance and some misuse of science in this area—no doubt." But he waves that resistance off and asserts, "it is not a mainstream position, not a significant part of the liberal agenda, etc." But that only holds true if groups that oppose biotech foods such as the Sierra Club, the Consumers Union, and Greenpeace can be considered to be on the fringe of Democratic Party politics.

Mooney does however acknowledge that he doesn't know if Democratic congressional resistance to allowing the Food and Drug Administration to go forward with its process for evaluating a biotech salmon variety that grows faster than conventional ones should count as a "misuse of science." He suspects that it is a mere "policy disagreement." Maybe. But consider that a bunch of mostly Democratic lawmakers sent a letter opposing FDA approval this summer. One signer of the letter, Sen. Mark Begich (D-Alaska), asserted, "We don't need Frankenfish threatening our fish populations and the coastal communities that rely on them." Actually a formal environmental assessment [PDF] submitted to the FDA last year concluded that producing the biotech salmon would be "highly unlikely to cause any significant effects on the environment, inclusive of the global commons, foreign nations not a party to this action, and stocks of wild Atlantic salmon."

What about vaccines? Berezow mentions data showing that vaccine refusals are highest in notoriously Blue states like Washington, Vermont, and Oregon. However, he could have cited the Pew poll that shows that 71 percent of both Republicans and Democrats would require childhood vaccination. Scientists favored mandatory childhood vaccinations by 84 percent.

However, the vaccine/autism scare was fueled in part by prominent lefties like Robert F. Kennedy, Jr. writing in popular publications like Rolling Stone and Salon. In fact, such fringey characters as then-Sen. Barack Obama lent further credence to the vaccine scare when in 2008 he declared, "We've seen just a skyrocketing autism rate. Some people are suspicious that it's connected to the vaccines. This person included. The science right now is inconclusive, but we have to research it." Sen. John McCain (R-Ariz.) made similar statements.

Mooney modestly asserts that "liberal journalists like myself… have pretty much chased vaccine denial out of the realm of polite discourse." And good on him. With similar modesty, I note that some of us who are not left-leaning have been working to do the same thing for some years now.

Over at the DeSmogBlog, Mooney continues his rousing defense of liberal scientific probity. The left doesn't abuse science; it merely has policy disagreements about what it all means. As an example of how policy disagreements can arise over scientific data, Mooney cites the left's affection for the precautionary principle. "There is always much scientific uncertainty, and industry claims it's safe, but environmentalists always want to be more cautious—e.g., adopting the precautionary principle," he notes. Then he adds, "The precautionary principle is not an anti-science view, it is a policy view about how to minimize risk." Really?

As University of Chicago law professor and current administrator of the White House Office Information and Regulatory Affairs Cass Sunstein noted in 2003, the precautionary principle [PDF] "imposes a burden of proof on those who create potential risks, and it requires regulation of activities even if it cannot be shown that those activities are likely to produce significant harms." Note specifically the latter point. Furthermore, Sunstein observed, the precautionary principle has become pervasive, being applied to areas such as "arsenic regulation, global warming and the Kyoto Protocol, nuclear power, pharmaceutical regulation, cloning, pesticide regulation, and genetic modification of food." The precautionary principle is unscientific in the sense that it demands the impossible: Researchers can never show that any technological or scientific activity will never produce significant harm.

As law professor Dan Kahan and his colleagues at the Yale Cultural Cognition Project have shown, the strong urge to avoid scientific and technological risk is far more characteristic of people who have egalitarian and communitarian values, that is to say, left-leaning folks. As I reported earlier, according to research by Kahan and his colleagues individualists tend to dismiss claims of environmental risks because they fear such claims will be used to fetter markets and other arenas of individual achievement. Hierarchicalists tend to see claims of environmental risk as a subversive tactic aiming to undermine a stable social order. In contrast, Egalitarians and Communitarians dislike markets and industry for creating disparities in wealth and power. In fact, they readily believe that such disparities generate environmental risks that must be regulated.

In other words, everybody has values that they are anxious to protect and everybody, including liberals, struggles with confirmation bias. The operation of the scientific process is the only truly effective way humanity has developed for overcoming confirmation bias and figuring out reality. In most cases it can reduce, but not eliminate, uncertainties, and correct mistakes as we go along. Unfortunately, as the autism/vaccine incident shows, unscientific approaches like the precautionary principle actually feed into the confirmation biases associated with a specific ideological tendency.

Lest anyone think that I'm defending Republicans, I will point to my various critiques of Republican views with regard to stem cell research, biological evolution, and climate change. Finally, the question recurs: Who is more anti-science, Democrats or Republicans? On the specific issues discussed above, I conclude that the Republicans are more anti-science. However, I do also agree with Berezow that scientific "ignorance has reached epidemic proportions inside the Beltway."

Ronald Bailey is Reason magazine's science correspondent. His book Liberation Biology: The Scientific and Moral Case for the Biotech Revolution is now available from Prometheus Books.