U.S. Senator Rand Paul (R-KY), a 2016 Republican White House hopeful, listens to a question while speaking to a group of state legislators at Murphy’s Diner in Manchester, New Hampshire January 14, 2015. REUTERS/Brian Snyder

The whole vaccine mess, in the United States and abroad, is a story of allowing anecdotes to trump statistical reasoning.

Some parents who saw their children get their shots, and then tragically saw them develop autism, inferred a causal relationship that wasn’t there. Fortunately, we have science to correct such errors, and in this case, science has done that.

But there’s another error of anecdotal reasoning here — not about vaccinations and the development of autism, but rather about a perceived correlation between leftwing, hippie-types and vaccine distrust.

And thus was born another myth — that denying vaccine safety, or avoiding vaccinations, is a liberal, granola thing. That’s the myth that began to shatter on Monday, when libertarian leaning senator and possible presidential contender Rand Paul said some truly alarming things about vaccines — suggesting they should be voluntary in many cases, and citing “many tragic cases of walking, talking, normal children who wound up with profound mental disorders after vaccines.”** (Don’t worry, I’m not only using the anecdote of Rand Paul to make this point. Stand by for the data.)

The truth is, the idea that vaccine skepticism lies on the political left never stood up to statistical scrutiny. I won’t belabor this point, since I’ve made it before, but this chart from Yale’s Dan Kahan says it all — while many beliefs change as you move from the left to the right of the political spectrum, doubts about vaccine safety really don’t move much, and if anything, increase slightly as you move to the right:


Source: Dan Kahan.

This suggests that political ideology is not the chief factor that predicts how a person feels about the safety of childhood vaccines. And indeed, we know that a much better predictor is being a conspiracy theorist, and holding beliefs like these: “The Apollo Moon landings never happened and were staged in a Hollywood studio” and “The assassination of Martin Luther King, Jr., was the result of an organized conspiracy by U.S. government agencies such as the CIA and FBI.”

Nonetheless, there is a relatively weak correlation in the figure above between political conservatism and an increased distrust of vaccines. But that probably shouldn’t be taken at face value, in light of other research suggesting that the association is really only with one branch of the complicated stew that we call American conservatism — namely, with libertarians or free market believers.

Indeed, a new study suggests that in 2009, in the wake of the swine flu (H1N1) scare, people who were less trusting of government were also less likely to get a swine flu vaccine.

All of this suggests that there may be an important tie between libertarian thinking — which puts great emphasis on preserving individual liberties from government intrusions — and doubts about government-required vaccinations. You don’t have to listen to Rand Paul to discern that; you can also get a taste by going over and reading Reason magazine, which hosted a 2014 debate over vaccinations that began with the observation, “Few issues divide libertarians so emphatically as government-mandated vaccinations against communicable diseases.”

The key word here, though, is “divide.” Even if there’s a strain in the community that doesn’t want the government telling them to vaccinate their kids, not all libertarians are against requiring vaccinations.

Sure enough, in the Reason debate, science correspondent Ronald Bailey valiantly defends vaccines against their critics, and does so from a libertarian perspective. For after all, everybody’s freedom has limits — and those limits are most clear when it comes to causing harm to others.

To this effect, Bailey quotes Justice Oliver Wendell Holmes’ observation that “The right to swing my fist ends where the other man’s nose begins,” and then goes on to note: “People who refuse vaccination are asserting that they have a right to ‘swing’ their microbes at other people. That is wrong.”

Right now, with Rand Paul — and to a lesser extent, Chris Christie — pushing certain buttons that potentially yoke together required vaccinations and government intrusions in the minds of conservatives, we badly need those on the right to read and heed someone like Bailey — who just called Paul out in a blog post.

That is, before the vaccine issue tips over into truly dangerous partisanship.

** Update: Later on Tuesday, Rand Paul tweeted a picture of himself getting vaccinated and said his views had been mischaracterized by the “liberal media.” If Paul does think vaccines are safe after all, that’s great to hear. The fact remains that concern about vaccines exists on the libertarian right, as well as on the left.

During a news conference, Speaker of the House John Boehner (R-Ohio) weighed in on the president's proposed budget and the debate over measles vaccinations. (AP)