There are many words I could attach to the dangerous freakshow that is Jenny McCarthy – self-made advocate for the pseudoscientific notion that there is a link between vaccines and autism: deluded, self-righteous, irrational, the Mayor of Wooville, etc. But I am always interested in the process that gets people to their profound confusion. I believe at the core of Jenny McCarthy’s tragic crusade is an utter lack of humility.

Her lack of humility also seems consistent with someone who has never risen to a level of competence, let alone mastery, in any intellectual discipline. Those who have understand on some level the value of excellence and expertise, and the gulf that separates superficial public knowledge (or what has been called in the internet age, the University of Google knowledge) from a functional depth of understanding.

This brings to mind yet another word that could apply to McCarthy – sophomoric. She has garnered just enough knowledge to think she knows what she is talking about, but not enough to appreciate the depths of her own ignorance.

I have known many such people in my life, usually distant family or casual acquaintences. A family friend, for example, without the slightest clue of real archaeology or history thought himself capable of overturning conventional wisdom regarding the history of human civilization. He wrote a book recasting human history in the light of recurrent alien visitations.  In conversation on his favorite topic he came across as a zealot, impressed with his own ideas, and lacking in the humility that genuine knowledge might have brought him.

Experts, of course, often fail to learn humility also.  It simply does not occur to them that the profound ignorance they had in their own field prior to becoming an expert (and of which they are now acutely aware), they still have in every other field. Those who fail to make this connection, for whatever reason, are almost destined to embarass themselves. (Linus Pauling, unfortunately for the legacy of this brilliant man, is now the poster child for this phenomenon.)

There is an important difference between my family’s eccentric friend and Jenny McCarthy – McCarthy is a celebrity and is not just self-publishing an obscure book, she is going on an anti-vaccine crusade that is actually having an impact.  I know I am being hard on her – but when you step into the public arena to advocate for a position that has direct health consequence, the gloves are off. The arena of scientific peer-review is a heartless meat-grinder – and whether she knows it or not, she asked for it.

Recently McCarthy appeared on CNN. During the interview she exposes her hubris in multiple ways. First, she declares that she is “certain” that vaccines caused her son’s autism. Premature or unjustified certainty is the golden road to pseudoscience. She is declaring that she has a fixed belief, immune to evidence and logic. That is how pseudoscience primarily operates – starting with a conclusion that believers just know is true, and then back-filling any justification they can find.

Such certainty requires a profound lack of humility, a lack of understanding of the nature of scientific evidence and the complexity of medical evidence and decision-making. In this particular case it requires an utter denial of the growing body of evidence that shows that vaccines are not linked to autism.

Throughout the interview she also betrays growing anger at the medical community.  She clearly believes that physicians and regulators are evil and self-serving – not that there are individual physicians and regulators who are corrupt or greedy, but that the vast majority are – everyone who disagrees with her beliefs. This, too, is a manifestation of profound hubris. She not only thinks she is smarter than the experts, she thinks she is more righteous.

So convinced is she in her own intellectual and moral superiority that she goes as far as to recommend that parents should take the care of their children into their own hands and ignore the advice of medical experts.

The thought process is clear. McCarthy is convinced that vaccines cause autism, and did so in the specific case of her son. The medical evidence disagrees with her belief, as does the FDA, the CDC, the Institute of Medicine, the American Academy of Pediatrics, The World Health Organization, and the vast majority of relevant experts. This does not give her the slightest pause, however. Rather than reexamine her conclusions or genuinely try to understand the position of those who disagree with her, she readily believes that she simply knows better than the world experts, and further, that they must be corrupt and greedy to the point that they will knowingly harm children to line their pockets. This conviction then fills her with self-righteous anger.

It is simply inconceivable to her that perhaps, just maybe, she might be wrong.

Lacking the ability to entertain such a proposition, McCarthy is descending steadily into the depths of pseudoscience and conspiracy theories. The world doesn’t agree with me, she reasons – it must be a conspiracy (it can’t be that I’m wrong). How deep does this conspiracy go? All the way.

If history is any judge, McCarthy will continue her descent, believing more and more ludicrous and paranoid nonsense. The only good thing about this typical course is that she will progressively marginalize herself. The scientific evidence will march on, leaving her and her cronies behind to whine about greed and conspiracies alongside the 9/11 truthers. The only question is how much damage will she do in the meantime.

It is concern over this damage (which is already underway in the form of an increase in vaccine-preventable diseases, as well as the use of many dangerous quack treatments like chelation) that motivates me and other science bloggers to take such a hard line with McCarthy. Orac has also taken her down nicely. Even Phil Plait, an astronomer, thought it necessary to call shinanigans on McCarthy.

Her crusade is destructive. It seeks to divide, rather than find common ground. It is dedicated not to a cause (children or autism) but to a conclusion (it’s the vaccines) that happens to be wrong. Along the way she seeks to burn down any institution that gets in her way – sowing public distrust in the medical community, in scientific medicine, in the vaccine program, and regulatory agencies. She believes the system has failed her, so now she advocates for medical anarchy – parents taking medical care into their own hands and not trusting their doctors.

To her all of this is better than to entertain, even for a moment, that perhaps she has not properly interpreted the complex scientific evidence – that maybe, just maybe, she might be wrong and the experts right.