I believe that anti-vaccination is an ideology, a cult, but its disciples pretend it is based on science. I am entirely confident their claim is false for a number of reasons, for example:

  • Anti-vaccinationists repeat claims that have been refuted, such as the Wakefield claim that MMR causes autism, which not even his original study supported. The mark of a science is that when things are shown to be wrong, they are abandoned.
  • Anti-vaccinationists rely on that most implausible of all logical fallacies, the appeal to conspiracy. A conspiracy to cover up vaccine harm would have to include, at a conservative estimate, hundreds of thousands of individuals and quite likely tens of millions. A conspiracy that remains intact and secret despite having the full scrutiny of Senators and crusading journalists on it, may safely be assumed not to exist.
  • Anti-vaccinationists attack people not ideas. Andrew Wakefield’s study was withdrawn because its conclusions were shown to be unsound, not because of who he is or what they said. If the establishment genuinely suppresses evidence of vaccine harm then the Wakefraud would never have been published in the first place – this much is obvious. The anti-vax crowd attack people like Dr. Paul Offitt, in the mistaken belief that by shouting down an advocate of science you somehow make the science go away (that does work with religions, of course).

But those are just my opinions. What I can say is that I know what would persuade scientists to change their minds. It’s actually reasonably easy to work out what you would need to get a large number of doctors and scientists to accept purported vaccine harms as real. Let’s focus for a moment on autism, as the crusade du jour of the anti-vax crowd. Here’s what you’d need:

1. A solid epidemiological study demonstrating, with high confidence, that there is a temporal link between vaccination and the onset of symptoms of autism.

To date there have been hundreds of studies, many of them very large, the total body of evidence covers many millions of children over a couple of decades in a dozen or more countries, and consistently shows no association. You’re not more likely to show symptoms soon after vaccination, and you’re not more likely to develop symptoms if you are vaccinated.

The few studies that do claim a link are very small and often poorly designed.

2. A credible mechanism by which vaccines might cause autism.

There have been a number of attempts at this. We’ve had thimerosal, gut inflammation, aluminium salts. Nobody has provided anything like a robust demonstration of any link between these and autism. No dose-response has been demonstrated. The PCR tests that purported to show measles bacteria in the gut of autistic children, are contaminated and borderline fraudulent. We also know that signs of autism are visible from birth and that genetic factors are dominant.

I can say with reasonable confidence that ant anti-vaccinationist who was able to provide the two things above, would find a receptive audience. These things would be highly persuasive.

So here’s the crucial question for any passing anti-vaxer:

What would persuade you to change your mind?

Here’s what not to say:

1. Demanding that something which happened, did not happen. “My child not to have become autistic” is a ridiculous thing to ask anybody to demonstrate, it can’t happen and it demonstrates a completely closed mind.

2. A randomised double-blinded trial. That won’t happen because it’s unethical. Regardless of how passionately you believe vaccines don’t work, scientists are pretty confident they do and there’s no way any ethics board would allow unvaccinated children to be deliberately exposed to infectious disease unprotected. And with large outbreaks in unvaccinated communities (e.g. the Amish in 2014), we basically have the vaxed vs. unvaxed evidence for disease outbreaks. You’re only going to get to look at potential harm, not at efficacy, because the jury’s in on that one.

3. Absolute proof of safety. This is science, all findings are provisional. If you’re going to accept the possibility that research could change scientific consensus – and if you don’t, then you need to talk to co-religionists such as Brian Hooker who conduct pseudoscientific studies looking to do just that – then you have to allow for the fact that there can be no such thing as absolute proof in science, no question is ever irrevocably closed.

So, go ahead: tell me what would change your mind.


  1. The timing of vaccines with a major neuronal remodeling ( see early childhood amnesia) in conjunction with Guillain-Barré syndrome would be a plausible mechanism. While the vaccine it self would not be the cause, it could be caused be many factors that stimulate a strong immune response, it would merely be the trigger. Full disclosure I’m fully vaccinated and support mandatory vaccinations.


    • No, coincidental timing is not a *mechanism* as such. A mechanism is a way that X could cause Y, not a record of Y following X.

      • Chris S

        It’s a bit like the underpant gnomes

        Step one – Align the two events
        Step two – ???
        Step Three – Autism!


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