The question Governor Chris Christie was asked seemed simple enough:
There’s a debate going on right now in the United States, the measles outbreak that’s been caused in part by people not vaccinating their kids. Do you think Americans should vaccinate their kids? Is the measles vaccine safe?
He could have just said: “The measles vaccine is safe and parents should get their kids vaccinated.” That appears to be what he believes, and the question required nothing more. But instead he decided to expand the context and give a more complex answer:
All I can say is that we vaccinated ours. That’s the best expression I can give you of my opinion. It’s much more important, I think, what you think as a parent than what you think as a public official. And that’s what we do. But I also understand that parents need to have some measure of choice in things as well so that’s the balance that the government has to decide.
In response to follow-up questions, he explained that vaccines for different diseases have different risks and benefits (which is true), so the government should be careful about which ones it mandates and which ones it leaves up to parents (which hardly anyone disputes). “I didn’t say I’m leaving people the option,” he protested. And when asked again whether vaccines were dangerous, he responded: “I didn’t say that.” But he also stopped short of saying: “The measles vaccine is safe.”
In short, if you parse Christie’s words very carefully and give him just a little benefit of the doubt, he didn’t say anything all that objectionable. But the question lingers: Why did he go there in the first place? Why not just give the simple answer, if that’s what he believes? After all, that’s the image Christie works so hard to project: a man who bluntly says what he thinks without a lot of political doubletalk. Why couldn’t “Is the measles vaccine safe?” get a “yes” answer, rather than a long-winded discussion followed by a denial that he was saying it was dangerous?
The obvious implication was that (as he progresses towards an as-yet-unannounced presidential campaign) Christie was trying not to offend some bloc of Republican voters. And many then jumped to the conclusion that the bloc in question is the anti-vaccine conspiracy theorists, who believe the scientifically groundless theory that vaccines cause autism.
The controversy Christie’s remarks started might have died out quickly, if rival presidential hopeful Senator Rand Paul hadn’t jumped in and said explicitly what Christie was accused of implying:
I’ve heard of many tragic cases of walking, talking, normal children who wound up with profound mental disorders after vaccines.
(He later backed off, claiming that after just means that vaccines and mental disorders are “temporally related”, not that one causes the other. So I’m sure he won’t mind if the media publishes a slew of stories of the form: So-and-so did something horrible after listening to Rand Paul. Or maybe a headline like “ISIS Beheads Hostage After Paul Speech”.)
But here’s the problem with the pandering-to-Republican-anti-vaxxers theory: First, there just aren’t that many anti-vaxxers. [See endnote 1] And second, they aren’t all Republicans. There’s a liberal version of anti-vax that focuses the conspiracy theory on drug companies rather than government. 
So the theory that a Republican primary might be decided by anti-vaxxers casting a single-issue vote is a little sketchy. That’s why as soon as their position got labelled as pandering to anti-vaxxers, other potential candidates took the opposite side of the argument  and both Christie and Paul had to back down to a certain extent.
So who were they pandering to? The Libertarian/Theocrat side of my model in “The Four Flavors of Republican“.
Again Paul was the more explicit:
The state doesn’t own your children. Parents own their children. 
In other words, decisions about vaccinations shouldn’t be made by the American people as a whole through the democratic process, or by the medical experts that the people delegate those decisions to. Libertarians believe those issues should be decided by sovereign individuals, and Theocrats want them decided by the fathers that God made sovereign over their households.
When you look at the world through either one of those lenses, vaccinations aren’t the point, they just symbolize larger issues about authority. So sure, I’m going to vaccinate my kids, but the decision should be up to me. “It’s an issue of freedom,” Paul said, and when the CNBC interviewer pressed him, he got sarcastic. “I guess being for freedom would be really unusual.”
This ties vaccinations to other “freedom” issues, like your freedom to go without health insurance rather than accept ObamaCare, your freedom to let your kids grow up ignorant rather than send them to a government-approved school (or report their home-schooling progress to an education bureaucrat), or your freedom to take the low wages and poor working conditions an employer offers rather than negotiate through a union. Newly elected North Carolina Senator Thom Tillis defended the freedom of food-sellers to set their own hygiene standards rather than be bound by government regulations:
“I was having a discussion with someone, and we were at a Starbucks in my district, and we were talking about certain regulations where I felt like ‘maybe you should allow businesses to opt out,'” the senator said.
Tillis said his interlocutor was in disbelief, and asked whether he thought businesses should be allowed to “opt out” of requiring employees to wash their hands after using the restroom.
The senator said he’d be fine with it, so long as businesses made this clear in “advertising” and “employment literature.”
“I said: ‘I don’t have any problem with Starbucks if they choose to opt out of this policy as long as they post a sign that says “We don’t require our employees to wash their hands after leaving the restroom,” Tillis said.
“The market will take care of that,” he added, to laughter from the audience. 
So in Tillis’ ideal republic, you would have to study the diverse hygiene practices of all the places you eat, so that you can make an informed decision about whether it’s safe to eat there. Because freedom.
Taken to its logical extreme, the freedom agenda says that you should be free to drive on the left side of the interstate. You wouldn’t, of course, because it’s dangerous and you’re not stupid. At least, you wouldn’t most of the time. Most people wouldn’t, most of the time.
But it wouldn’t take many to screw everything up. What if, of all the drivers who would be traveling north during your next trip south down the interstate, you knew that only one would be using his freedom to drive on the left side and come straight at you? How would that change your driving experience?
Here’s what it boils down to: Human beings are simultaneously individuals and members of society, not fundamentally one or the other. Some issues (like free speech) are easier to understand from the individual point of view, while others (like traffic) require a social point of view. 
Public health is fundamentally social. Germs pay no attention to your individuality; they just spread through the herd. You personally may do everything right, but whether or not you get sick also depends on social things like the quality of the sewage system, whether other infected individuals have access to health care or paid sick leave, how well your city controls rats and other vermin, whether restaurant workers wash their hands, and what percentage of people get vaccinated. In extreme cases, it depends on really draconian government interventions like quarantines and travel restrictions.
No matter what kind of intellectual contortions you do, you can’t square all that with a pure individual-freedom agenda. What if a free individual exposed to Ebola doesn’t want to be quarantined in a treatment facility? (Maybe he has his own theory about diseases and doesn’t believe all this germ-and-virus nonsense. Or maybe he was only probably exposed, and he’s willing to risk it.) If your ideology limits you to looking at everything from the individual-freedom viewpoint, your thinking about public health is going to be crippled.
So that’s who Christie and Paul were pandering to this week: people whose thinking about public health has been crippled by individualist ideology. If either becomes president, he may continue to pander to them.
 Anti-vaxxers only dangerous because it doesn’t take many to screw up herd immunity, which protects people who can’t use the vaccine. (In other words: Even if you can’t be vaccinated or haven’t been vaccinated yet, you’ll be safe because you are unlikely to come into contact with sick people.) According to the World Health Organization, as reproduced in Wikipedia, the herd immunity threshold for measles is 83-94% vaccinated, so as few as 6% in a local community might be enough to make that community vulnerable to an outbreak.
If you think of this in terms of the free-rider problem, the herd immunity threshold measures how many free riders the vaccination system can stand before it starts breaking down.
 Anti-vaccine liberals are sometimes used to prove that in their own way Democrats are just as much at war with science as Republicans who deny climate change or evolution. But here’s the clear difference: Anti-science liberals are on the fringe of the Democratic Party, and elected officials seldom pay much attention to them. Conversely, climate-change denial is a core position of the conservative base, so virtually every elected Republican has gotten in line.
 Marco Rubio demonstrated that a Republican presidential contender can give the simple, direct answer: “There is absolutely no medical science or data whatsoever that links those vaccinations to onset of autism or anything of that nature. And by the way, if enough people are not vaccinated, you put at risk infants that are three months of age or younger and have not been vaccinated and you put at risk immune-suppressed children that are not able to get those vaccinations. So absolutely, all children in American should be vaccinated.”
Also Ted Cruz: “On the question of whether kids should be vaccinated, the answer is obvious, and there’s widespread agreement: of course they should.”
But both avoided a direct endorsement of mandatory vaccinations, like Ben Carson’s.
 Rekha Basu of the Des Moines Register had the right response:
No, we don’t own our children. From slavery to child sexual abuse, the notion of owning another human has led to nothing good. Legally, we’re responsible for our kids and their care, feeding and safety until they’re old enough to take care of themselves. But they are autonomous human beings, which is why, unlike property, there are laws and standards governing what we can and can’t do to them.
 We’ve seen this two-step before. The same politicians who say that a well-informed public can sort things out without government help will also oppose any regulations that inform the public. Today, Tillis says he’d make Starbucks post that sign, but when the time came to vote on it he actually wouldn’t, for exactly the same reason: The market can sort out whether businesses should have to post their hygiene policies.
 It’s like the wave/particle thing with light, if that analogy makes sense to you. If not, forget I mentioned it.