Jenny McCarthy’s Battle With Sense

Originally published at The 21st Floor…

For reasons that I don’t want to think about too much lest I lose the will to continue breathing in and out, US broadcaster ABC recently bypassed several thousand people who know what they’re talking about and petitioned actress and soft-porn star Jenny McCarthy for her views on a recent study reporting no evidence for a gastrointestinal disorder causing autistic spectrum disorders, and no evidence that special diets alleviate symptoms of autism. Predictably, McCarthy was incredulous, maintaining that she had witnessed these special diets help her autistic son and that doctors need to, and I quote, “start listening to our anecdotal evidence.”

McCarthy, for context, is a seasoned mouthpiece for all sorts of conspiracy theories regarding autism. An entire course in critical thinking could be built solely around her output on the science behind the subject. So convinced is she of the link between MMR vaccinations and autism that she has created complex ad hoc refutations of the overwhelming numbers of studies which have found no such link, most of which involve some hegemonic cabal of evil scientists living in the pockets of the pharmaceutical industry. Behind this stubborn refusal to accept scientific consensus on the matter is Jenny’s personal observation that her son’s autistic behaviour (there’s actually good reason to believe that her son was misdiagnosed) began shortly after he recieved his vaccinations. This is a hugely flawed basis for such deeply ingrained beliefs; not only does it equivocate correlation and causation, but because autism diagnoses are generally made in infancy it would be entirely logical to actively expect that some diagnoses would coincide with vaccination even if there was no causal link between the two. The illusion of cause and effect is strong, however, and McCarthy has wound up in the grip of it’s specious appeal. It’s so satisfying as an explanation that she’s allowed herself to become convinced that anyone who opposes it is an elitist or a conspirator. So she disregards scientific consensus and makes appeals to the public for them to do the same. On the basis of her personal experience, her anecdotal evidence.

“Who needs science when I’m witnessing it every day in my own home? I watched it happen. At home, Evan is my science.”

– Jenny McCarthy

If you don’t do a whole lot of thinking, “listen to my anecdotal evidence” sounds great. It’s saying “look, I’ve experienced this and you haven’t, who are you to tell me what’s right and what’s wrong?” It’s a sentiment which tempts you to cheer for it. It’s irritating and frustrating when you’ve seen something with your own eyes and someone tells you you’re wrong. Especially when the issue under scrutiny centres on the wellbeing of an individual you love and care for very much and that the people criticising you have never met. Jenny’s a mum, right? She knows her child better than anyone, yes? What gives these elitist scientists the right to tell her she doesn’t know what she’s talking about?

Unfortunately, being a mum doesn’t make you any more an expert on childhood diseases and their treatments than my penis makes me an expert on urology.

The problem with accepting anecdotes as evidence is the fact that, leaving wilfull dishonesty to one side, human beings are innately unreliable. We see things that aren’t there. We attribute causes and effects where there are none. We’re suckers for confirmation bias – the psychological phenomenon whereby we tend to pay disproportionate attention to phenomena that support our beliefs. We tend to interpret things to fit our expectations. Science goes to painstaking lengths to eliminate all of these biases and misperceptions, which is why it produces reliable results.

“The first rule of science is not to fool yourself, and know that you are the easiest person to fool.”

– Richard Feynman

Jenny McCarthy may well have seen improvements in her son but, because of these all-too-human weaknesses in perceiving reality, we can’t just take her (or anyone’s) word for it that the diet was the cause. Maybe he was going to get better anyway? Maybe it was some kind of placebo effect by proxy? Maybe he was never even autistic in the first place? Maybe she’s just gone mad? The fact is, that when we control for such biases, the effect of this diet disappears. Autistic children on the diet fare no better, on average, than autistic children who are eating normally. And scientists aren’t just being smart-arsed party-poopers: there are potentially serious consequences for putting children on restrictive diets, so why risk it for no better reason than that Jenny McCarthy has an anecdote about how it worked for her kid?