Ever since Chris Mooney's Republican War on Science was published in 2005, folks have been looking for a way to argue that Democrats are just as bad. The standard example for this counternarrative, one which Mooney even offered in his book, was vaccine denial – the claim that vaccines cause autism or are otherwise dangerous.

Intuitively, this seems right. The folks and venues touting antivaxx conspiracy theories tended to be New Agey outlets, and the places facing outbreaks of vaccine-preventable diseases tended to be liberal strongholds, like Boulder, CO or Marin County, CA. That must mean liberals are more likely to buy into vaccine denial, right? Unfortunately, no pollster ever seemed to include a question about vaccine denial in a survey along with questions about political party or political ideology.

Until recently.

Yesterday, Public Policy Polling, an outfit known for asking wacky but surprisingly informative questions, asked people about a host of conspiracy theories. The Atlantic Wire's Philip Bump summarizes the results nicely, and there's much to return to here. For our purposes, the most interesting outcome is that 26% of Republicans think vaccines cause autism, compared to 16% of Democrats (that's on p. 21 of the PDF).

Indeed, the only claimed conspiracies which Democrats were more likely to back than Republicans were: "the moon landing was faked" (D: 7%, R: 4%, I: 9%, all within the margin of error), "President Bush intentionally misled the public about the possibility of weapons of mass destruction in Iraq to promote the Iraq war" (D: 72%, R: 13%, I: 48%), "the CIA was instrumental in distributing crack cocaine into America’s inner cities in the 1980s" (D: 14%, R: 9%, I: 21%), "Paul McCartney actually died in a car crash in 1966 and was secretly replaced by a lookalike so The Beatles could continue" (D: 7%, R: 4% I: 5%, inside the margin of error), "the United States government knowingly allowed the attacks on September 11th, 2001, to happen" (D: 14%, R: 8%, I: 12%). Republicans are more likely to believe in aliens and in bigfoot, that aliens crashed at Roswell and shape-shifting reptiles rule our world, that Saddam Hussein played a role in 9/11 and a secretive power elite secret rules the world, that the government adds mind control messages to TV signals, sprays evil chemicals into the air, and fluoridates water for nefarious purposes, that bin Laden is alive and Oswald didn't act alone, that pharmaceutical companies invent new diseases to make money and vaccines cause autism. They also are more likely to think President Obama is the anti-Christ and global warming is a hoax. Republicans endorse more conspiracy theories, and with greater fervor, than Democrats (even stretching back to conspiracies of yesteryear, like McCartney's supposed death or the CIA's ambiguous role in the Contras' drug dealing).

According to a survey last December, Republicans aren't just more likely to think vaccines cause autism, they are also less likely than Democrats to think "the schedule of vaccines recommended by the Department of Health and Human Services is safe." At the time, Adam Berinsky, the researcher who commissioned the survey, suggested that Republicans' negative reaction might simply be "a result of the interaction between anti-government sentiment among Republicans and the mention of a government agency in the question." Yet that survey also found that Republicans were more likely to think vaccines were associated with autism, cancer, and heart disease (and less likely to link it with diabetes).

Berinsky compared those conspiratorial beliefs with another conspiracy theory, finding that people who are less trusting of the vaccine schedule are more likely to think President Obama wasn't born in the United States. In other words, belief in one conspiracy seems to predispose you to others. Democrats who were more dubious of the vaccination schedule were also more likely to doubt that the President was born where all evidence indicates he was born. This parallels findings from Australian researchers including Stephan Lewandowsky, who found that people who endorsed conspiracy theories like the CIA assassinating Martin Luther King, Jr., or NASA faking the moon landing are more likely to reject climate change. (Lewandowsky's paper itself inspired such a fury of conspiracy-mongering that he was able to generate another paper about the conspiracy theories spawned by the first.)

I wrote to Berinsky to ask whether he'd compared vaccine denial with other conspiracy theories, like creationism or climate change denial, and he was able to make a comparison with climate change denial. "As you would expect," he told me, "anti-vaccine people are climate change deniers."

That's what you'd expect from the evidence that conspiracy-mongering begets conspiracy-mongering. It's not what you'd expect if you shoehorn vaccine denial into the role of a liberal counterpart to conservative science denial.