You hear a lot about the politicization of science, but the real problem is the moralization of science. The New York University psychologist Jonathan Haidt has made a compelling case that moral differences drive partisan debates over scientific issues. Dan Kahan and others at the Yale Cultural Cognition Project have identified cultural differences that bias how people assimilate information. Together, Haidt and Kahan's research suggests that what you believe about a scientific debate signals to like-minded people that you are on their side and are therefore a good and trustworthy person. Unfortunately, this means that the factual accuracy of beliefs is somewhat incidental to the process of moral signaling.

For an illustration, consider a recent skirmish between Skeptic editor Michael Shermer and Mother Jones writer Chris Mooney. Shermer, whose political views lean toward libertarianism, wrote a column for Scientific American titled "The Liberal War on Science," noting the left's tendency to deny human cognitive evolution and the safety of biotech crops and nuclear power. Mooney, author of a book called The Republican War on Science, retorted with a story headlined "There is No Such Thing as a Liberal War on Science." The right's denial of evolutionary biology and man-made global warming, Mooney argued, are much more consequential for public policy. While acknowledging that a substantial percentage of Democrats don't believe in human evolution or man-made global warming either, Mooney took comfort in the fact that "considerably fewer Democrats than Republicans get the science wrong on these issues."

Kahan identifies the ideological left as people who tend to have egalitarian or communitarian views. Egalitarians want to reduce disparities between people, and communitarians believe that society is obliged to take care of everyone. People holding these cultural values are naturally biased toward collective action to address inequality and the lack of solidarity. When the results of scientific research are perceived to perturb those values, it should be no surprise that left-leaners have a greater tendency to moralize them, to favor government intervention to control them, and to disdain conservatives who resist liberal moralizing.

Haidt's moral survey data suggests that ideological conservatives have a greater tendency to moralize about purity and sanctity than do liberals. This may be so, but it's pretty clear that liberals are not immune from concerns about purity and sanctity. While conservatives moralize about the purity and sanctity of sex and reproduction, liberals fret about the moral purity of foods and the sanctity of the natural world.

One particularly powerful moralizing tool that is chiefly deployed by progressives is the precautionary principle. Mooney blandly writes that this "is not an anti-science view, it is a policy view about how to minimize risk." Beliefs about how much risk people should allowed to take or to be exposed to are moral views. In fact, as Kahan and his colleagues have shown, the strong urge to avoid scientific and technological risk is far more characteristic of people who have egalitarian and communitarian values. The precautionary principle is not a neutral risk analysis tool; it is an embodiment of left-leaning moral values.

Let's look at what scientific research says—and does not say—about the moralized issues of climate change, biological evolution, nuclear power, genetically modified crops, exposure to synthetic chemicals, concealed carry of guns, vaccines, video games, fracking, organic foods, and sex education. I chose this list largely because I could find relevant ideological polling data and majority scientific opinions. Applying Mooney's standard of seeing whether fewer of one ideological tendency gets the science wrong, we find that Democrats are less wrong on four issues, Republicans are less wrong on six, and the parties are tied on one.

Climate change: The majority of climate scientists believe that human activity is causing the earth's temperatures to increase. A recent Pew Research poll found that two-thirds of Americans also believe that the earth is warming. But a deep partisan divide yawns between conservatives and liberals on the cause of the warming: Only 16 percent of conservative Republicans believe that human activity is responsible, whereas 77 percent of liberal Democrats do. Moderate Republicans and Democrats accept human responsibility by 38 and 51 percent, respectively. Advantage: Democrats.

Evolution: Both Shermer and Mooney cite a 2012 Gallup Poll that found that 46 percent of Americans are young Earth creationists—that is, believe that God created humans beings in their present form within the past 10,000 years. These constitute 41 percent of Democrats and 58 percent of Republicans. Adding those partisans of both parties who are intelligent design creationists, i.e., believe that God guided the process of evolution, the poll shows 73 percent of Democrats and 89 percent of Republicans holding creationist beliefs. In fact, 78 percent of Americans are either young Earth or intelligent design creationists. A 2009 Pew Research poll produced numbers that were lower but still high, showing that 52 percent of Democrats and 65 percent of Republicans can be counted as either intelligent design or young Earth creationists.

The Pew Research poll also reported that 87 percent of scientists believe that humans evolved through entirely natural processes, whereas only 8 percent thought that God guided the process. Advantage: Democrats.

Nuclear power: A 2012 Gallup Poll found that 72 percent of Republican think that nuclear power is generally safe, compared to just 45 percent of Democrats. Given these views, is it not surprising that 64 percent of Republicans and 41 percent of Democrats favored expanding this source of carbon-free energy. A 2009 Pew Research poll reported that 70 percent of scientists favored building more nuclear power plants. Although it seems unlikely that scientists would favor nuclear power if they thought it unsafe, perhaps the Pew poll is measuring cost/benefit views rather than safety views. I have not been able to uncover recent surveys of expert opinion with regard to the safety of nuclear power plants, but in a survey done more than a year after the Three Mile Island nuclear plant meltdown, 90 percent of the scientists surveyed said the nuclear power should proceed. A 1986 poll of radiation health scientists reported that the vast majority believed "the public's fear of radiation is substantially greater than realistic, that TV, newspapers and magazines substantially exaggerate the dangers of radiation."

In 1993, a study titled "Decidedly Different" contrasted the views found in survey data gathered from the public and from members of the American Nuclear Society. The survey asked both groups, "How likely do you think it is that activities at the nation's nuclear facilities will in the future cause health problems for those who live near such activities?" The responses were measured on a scale of 1 to 10, with 1 being not likely to 10 being extremely likely. Thirty-three percent of the public picked 10; 40 percent of the experts picked 1. Overall, 69 percent of the public thought such future health effects were likely and 80 percent of the experts did not.

Recall Mooney's claim that there is "no currently pressing issue…where the left is monolithically in denial of basic science, or where this drives mainstream political policy—e.g., drives the stance of most elected Democrats." It is true that the Obama administration has been pro-nuclear, but looking around the country it's easy to find elected Democrats who take the opposite position. For example, Massachusetts attorney general Martha Coakley sued to close down the Pilgrim plant, Vermont Governor Peter Shumlin is pushing to close the Vermont Yankee plant, and New York Governor Andrew Cuomo favors shutting down the two Indian Point reactors in 2013 and 2015. These Democratic politicians seem pretty "mainstream," and there are no comparable officials from the GOP taking similar stances. Advantage: Republicans.

Biotech crops: Every independent scientific group that has ever evaluated biotech crops has found them to be safe for people and the environment. Sadly, polling data suggests that both Democrats and Republicans have been spooked by anti-biotech disinformation campaigns. The most recent polling on this issue I could find was a 2006 survey by the Pew Trusts that reported 48 percent of Republicans believe that biotech foods are safe, compared to 28 percent who did not. Democrats are just slightly less likely to think biotech foods are safe, with 42 percent saying they are and 29 percent saying they aren't. As far as mainstream impact goes, the California Democratic Party endorsed last year's Proposition 37, which would have required the labeling of all foods made with ingredients from biotech crops. Advantage: Republicans.

Synthetic chemicals: The chief worry about synthetic chemicals, stoked originally by Rachel Carson in her 1962 book Silent Spring, has traditionally been cancer. Yet as the American Cancer Society notes, "Exposure to carcinogenic agents in occupational, community, and other settings is thought to account for a relatively small percentage of cancer deaths—about 4% from occupational exposures and 2% from environmental pollutants (man-made and naturally occurring)." A recent article the journal Lancet Oncology argued that costly regulatory efforts to reduce exposures to trace amounts of man-made chemicals divert resources from truly effective measures to prevent cancer, such as modifying lifestyle factors such as smoking, obesity, and sunlight exposure.

What do experts think? Polling data is scarce on the ground, but a 2009 survey of the members of the Society of Toxicology decisively rejected the assertion that exposure to any level of chemicals is unacceptable by 92 percent to 8 percent. In addition, 87 percent the society's members disagreed with the claim that organic and natural products are safer, and 81 percent disagreed with idea that detecting any level of chemicals in a person's body shows a health risk.

Democrats are more worried than Republicans about trace exposures to synthetic chemicals. As part of its campaign for the Safer Chemicals Act, the environmental lobbying group, the Natural Resources Defense Council commissioned a 2012 poll that found that 79 percent of Democrats wanted "stricter regulation of chemicals produced and used in everyday products," compared to 58 percent of GOP voters. In another section of that poll, respondents were primed with a choice of regulating chemicals that could cause cancer or other health problems or protecting chemical industry jobs. In this case, 62 percent, not too surprisingly, favored stricter regulation. With regard to "mainstream" impact, every one of the 30 sponsors of the Safer Chemicals Act was a member of Senate's Democratic caucus.

Back in 2005, a Harris Interactive poll reported, "A majority (58%) of U.S. adults believe that chemicals and pollutants are more of a threat to people like them now than they were 10 years ago." But as Environmental Protection Agency data show, major air pollutants have been declining in the United States for decades. Carbon monoxide down 82 percent since 1980, ozone down 28 percent, nitrogen oxides down 52 percent, sulfur dioxide down 76 percent. The Harris poll also reported that 65 percent of Americans were very worried or worried about the chemicals or pesticides that are used to grow the foods they eat. Advantage: Republicans.

Guns: In the wake of the Newtown mass murder, the country is once again embroiled in the gun control debate. One contentious question is whether allowing citizens to carry concealed weapons decreases or increases crime. A 2012 poll for Reuters found that 82 percent of Republicans and 72 percent of Democrats supported laws allowing law-abiding citizens to get a permit to carry a concealed weapon.

This is a hotly disputed area, but a 2004 National Research Council report concluded that "There is no credible evidence that 'right-to-carry' laws, which allow qualified adults to carry concealed handguns, either decrease or increase violent crime." In 1994, Congress banned "assault weapons" and large-capacity ammunition magazines. The bans expired in 2004. In a recent Quinnipiac University poll, 81 and 77 percent of Democrats want to ban assault weapons and large-capacity magazines, respectively. On the other hand, 55 and 58 percent Republicans oppose both bans. Did the 1994 bans actually reduce gunshot victimizations? A 2004 study by University of Pennsylvania researchers concluded the if the ban had been renewed, its "effects on gun violence are likely to be small at best and perhaps too small for reliable measurement." Advantage: Republicans (barely).

Vaccines: What about the partisanship over vaccines? Mooney more or less concedes that some prominent figures on the left fanned the flames over the bogus claim that vaccines cause autism. But GOP luminaries such as Rep. Michele Bachmann and Rep. Tim Burton also promote nutty anti-vaccine theories. The good news is that the 2009 Pew Research poll mentioned above found that 71 percent of both Republicans and Democrats would require childhood vaccinations. Scientists favored mandatory childhood vaccinations by 84 percent.

On the other hand, a fight between Texas Gov. Rick Perry and Rep. Michele Bachmann in the GOP presidential primary broke out over whether or not vaccinating teenage girls against human papilloma virus (HPV) should be mandated. Being infected with HPV substantially boosts the risks of cervical cancer. In 2006, a Christian conservative activist Bridget Maher the Family Research Council warned, "Giving the HPV vaccine to young women could be potentially harmful, because they may see it as a license to engage in premarital sex." For those worried about promiscuity, a preliminary study reported in 2012 reported that girls vaccinated against HPV are no more sexually active than those who have not been. Frankly, not getting your kids vaccinated against HPV is just plain stupid. In the end, I agree with Mooney that there is no really good data on the ideological breakdown of vaccine denialism. Advantage: It's a draw.

Video games: In a superb review article in the February/March 2013 issue of American Psychologist, Texas A&M researcher Chris Ferguson takes his academic colleagues to task for promoting way beyond their data the claim that playing video games leads to social violence. Ferguson also pointed out in the Washington Post that "Video games have become more popular and more violent, while youth violence has declined." Yet a February 2013 Harris Interactive survey found that 58 percent of adults believe there is link between violent video games and violent teen behavior. A post-Newtown Gallup poll reported that 55 percent of Republicans and 44 percent of Democrats thought that decreasing depictions of gun violence on TV, in movies, and in video games would be an effective approach to preventing mass school shootings.

Interestingly, the only two bills currently before Congress aiming at supposed video game violence were introduced by Democrats, Sen. Jay Rockefeller of West Virginia and Rep. Jim Matheson of Utah. In January, President Obama declared that Congress "should fund research into the effects that violent video games have on young minds." On the other hand, Republican Sens. Chuck Grassley of Iowa and Lamar Alexander of Tennessee also blamed violent video games for fomenting gun violence. And the polls make it clear which party is worse here. Advantage: Democrats.

Fracking: A March 2012 Pew Research poll reported that, among respondents who had heard of fracking to obtain natural gas from shale, 73 percent of Republicans favored it whereas only 33 percent of Democrats did. Researchers are still investigating whether or not natural gas and other contaminants from fracked wells is seeping into drinking water supplies. The EPA expects to issue a comprehensive report on this issue next year. Howsoever those investigations turn out, technologies exist to reduce the chances that natural gas from drilling will contaminate people's wells.

A December 2012 Quinnipiac Poll of New York State residents reported that 61 percent of Democrats thought that fracking will cause environmental damage, compared to only 25 percent of Republicans. On January 3, 2013, the New York Times reported that preliminary report on fracking by the New York State Health Department had looked into "the potential impact of fracking on water resources, on naturally occurring radiological material found in the ground, on air emissions and on 'potential socioeconomic and quality-of-life impacts.'" The analysis concluded, according to the Times, that "the much-debated drilling technology known as hydrofracking could be conducted safely in New York."

The chief scientific question is how producing and burning shale gas will effect greenhouse gas concentrations in the atmosphere. In 2011, Cornell researchers published a study suggesting that methane escaping from wells could make fracking "dirtier than coal" when it comes to boosting man-made global warming. On the other hand, a 2011 National Energy Technology Laboratory life-cycle analysis finds that the average natural gas baseload electric power generation has a life cycle global warming potential that is 55 percent lower than the average coal baseload power generation, on a 100-year horizon. In other words, burning natural gas produces less than half of the globe warming carbon dioxide that coal does. Most researchers believe that burning natural gas will reduce greenhouse gas emissions and thus lower the risks from future global warming. Last week the New York State Assembly, where Democrats outnumber Republicans 2 to 1, voted to extend the current moratorium on fracking in the state until 2015, by a vote of 95 to 40. Advantage: Republicans.

Organic food: A February 2013 Public Policy Polling survey that asked respondents if they prefer organic food when it's available, or do they not care? Fifty percent of Democrats would prefer to buy organic, but only 35 percent of Republicans would bother. People choose organic foods often in the belief that they are better for the environment and more nutritious. A 2012 article in the Journal of Environmental Management reviewing 71 studies on the impact of organic farming on the environment concluded that organic practices do "not necessarily have lower overall environmental impacts than conventional farming." In September, researchers at Stanford University published a review in the Annals of Internal Medicine of 237 studies detailing the nutritional differences between organic and conventional foods. It too found few significant difference between organic and non-organic foods. Amusingly, a May 2012 study published in the journal Social Psychological and Personality Science by a Loyola University psychologist found that organic foods provoked sense of moral superiority in people, making them less altruistic. Advantage: Republicans.

Sex Education: The most even-handed survey of ideological attitudes toward both abstinence-only and comprehensive sex education is a 2006 study published in JAMA Pediatrics. That survey found that 67 percent of liberals opposed abstinence-only sex education, while 40 percent of conservatives did. It should be noted that 92 percent of liberals and 70 percent of conservatives supported abstinence-plus sex education, i.e., includes instruction concerning contraception, sexually transmitted diseases, and condom use. Although there are some outliers, most research agrees with a 2011 PLoS One study that reviewed sex education programs from 48 states that concluded that the "data show clearly that abstinence-only education as a state policy is ineffective in preventing teenage pregnancy and may actually be contributing to the high teenage pregnancy rates in the U.S." For what it's worth, comprehensive sex education has been endorsed by most relevant medical societies. Advantage: Democrats.

As a libertarian, my cultural bias is toward keeping as many issues and problems out of the realm of collective action as possible. Scientific research may identify some problems that truly require a collective response—perhaps man-made global warming—but for social peace, the default response toward most issues should be social and political tolerance of individual choices. Texas A&M researcher Chris Ferguson gets it right on how scientists should respond to any efforts to moralize scientific findings. "Put simply, it may be best for scientists to remain committed to the production of objective information," he writes. He adds, "Deciding how such information 'should' be used arguably strays into advocacy and becomes problematic." Knowing that something is factually true does not necessarily tell us what to do about it.