From time to time celebrities publicly discuss their opinions on scientific topics, and the results are usually not pretty. I have discussed previously the folly of Jenny McCarthy, for example, in using her dubious celebrity to promote anti-vaccine nonsense. Now The Donald has joined the ranks of people who are mostly famous for being famous who feel their celebrity gives them license to pontificate publicly about complex scientific issues. Trump told a Fox News audience that he strongly believes vaccines are causing the increase in autism diagnosis. He based this upon his scientific training, thorough reading of the relevant scientific literature, and consultation with experts – no, I mean based upon his casual observation and naive assumptions. Hey, he has an anecdote.

Here is the core of his rant:

“I’ve gotten to be pretty familiar with the subject. You know, I have a theory — and it’s a theory that some people believe in — and that’s the vaccinations. We never had anything like this. This is now an epidemic. It’s way, way up over the past 10 years. It’s way up over the past two years. And, you know, when you take a little baby that weighs like 12 pounds into a doctor’s office and they pump them with many, many simultaneous vaccinations — I’m all for vaccinations, but I think when you add all of these vaccinations together and then two months later the baby is so different then lots of different things have happened. I really — I’ve known cases.”

OK, it’s easy for a lay person to get caught up in a complex scientific question and get overwhelmed by information from one side. If you naively watch Loose Change, for example, without being familiar with the whole 911 conspiracy thing you might be led to believe there is something sinister going on. That’s how propaganda of that sort often works – overwhelm your audience with factoids, distorted and cherry-picked information, and apparent correlations and weave them into an emotionally compelling story. If you listen to just one side of any scientific debate you will probably be convinced that that side has a strong and perhaps even iron-clad case. Only when the other side has an opportunity to make their case do you see how the information you were given was systematically biased in one direction.

Unfortunately, it is part of human psychology that once we attach ourselves to one side of a controversy we tend to stick to our guns. We invest in that side, identify with it, and then defend it at all costs. Humans are generally quite skilled at rationalization (probably because we get so much practice), so it can be hard to dislodge someone from a position they strongly hold. We often refer to this phenomenon as “drinking the Kool-Aid” (named after the Jonestown cult that committed mass suicide by drinking poisoned flavored drink that actually was not Kool-Aid).

Part of the point of science and skepticism is to transcend this basic human psychology by investing in a process, not a conclusion – the process of science. It is better to listen to whatever logic and evidence says is most likely to be true, rather than what we wish to be true or whichever “side” we have already invested in. We also recognize that many scientific topics are very complex, and require a large body of specialized knowledge in order to know and understand the relevant evidence. This is why we look to expert opinion to help us make sense of complex questions, and why a consensus of expert opinion should not be casually tossed aside.

While the tendency to do just that is not unique to celebrities, the fact of their celebrity often makes them feel justified in putting forward their own personal opinion on topics. This is probably especially true of those like Trump who are very successful in one area of their life, in his case finance. What we have in Trump, apparently, is the perfect storm of arrogant ignorance.

Just about everything Trump said was demonstrably wrong. First he assumes that the increase in autism diagnosis is due to a real increase in the prevalence of autism. As I have discussed previously, this is likely not true. Most if not all of the increase is due to the broadening of the definition of autism, diagnostic substitution, increased surveillance and awareness, and an increased willingness to accept the diagnosis.

Donald then buys into the “too many too soon” propaganda of the anti-vaccine movement. He refers to injecting “monster vaccines” into tiny child bodies, and advises the expert medical community to spread out the vaccine more. Trump is probably unaware of the fact that this has already been studied. The evidence available indicates that adhering to the standard vaccine schedule was associated with no negative outcomes, but spreading out the vaccines was associated with a higher risk of developing vaccine-preventable illness. That’s strike two.

Trump caps his rant with an anecdote from someone who works for him, possibly the source of the anti-vaccine propaganda in which he is now so thoroughly steeped. This is the common tale of a child who was allegedly perfectly normal at 2 years old, then got a “monster vaccine”, and then two months later had serious neurological problems. I cannot comment on this specific case, because it is a hearsay anecdote. But when similar cases are investigated it is often found that signs of autism were present long before parents later report them to have begun. When objective evidence is available, there is no correlation in timing between vaccines and autism onset. It is only later, in the parents memory, that the spurious correlation exists.

No one likes to hear this – that their memories are not accurate, but deal with it. The scientific evidence on memory is quite clear on this point – our memories stink. We fuse and distort memories, we rewrite them every time we recall them. We tend to compress timelines (a process known as telescoping), and we tend to anchor one event to another events. These distortions are also not random – we develop a narrative of what we think happened, and then systematically adjust the details of our memories to match and enhance the narrative. Once a parent thinks that vaccine caused their child’s disorder, they will come to honestly remember the standard tale – my child was perfect, he got a vaccine, and then all the problems began. Objective facts, however, rarely support such clean stories.

Further, even when a temporal correlation with vaccines exists, this correlation does not prove causation. Children receive vaccines throughout the time period when the symptoms of autism become noticeable or prominent to the point that they cannot be ignored. Anything that develops in young childhood, therefore, will have some correlation to vaccines.

I don’t necessarily blame Trump for being so hopelessly wrong in his “theories.” He is the victim of a well-funded propaganda organization dedicated to blaming vaccines for autism and anything else they can. I do blame him to some extent – he is a person of means and should know enough not to trust what is essentially rumor and opinion. To the credit of one of the reporters of Fox they pointed out that the consensus of scientific opinion is that vaccines do not cause autism, and even mentioned that it was once blamed on mercury, which was removed from vaccines years ago, but the prevalence is still rising. Trump responded to this with a dismissive, “I know” – meaning that he knows scientists disagree with his opinion. He must have a very elevated assessment of his own scientific opinions, therefore, to so casually toss aside the opinion of actual experts.

But here is what I mostly blame Trump for – expressing his ill-conceived opinions on national television knowing that his celebrity will give them undue attention and weight in the public’s eye. I do hold celebrities responsible for using their celebrity to advance their personal opinions on important medical issues. They are not medical experts. They should not be giving out medical advice on national television, without making the effort to vet their opinions with experts. That is irresponsible, even callous. For this reason Trump deserves to be ridiculed for his opinions. He is not just a private citizen who ran afoul of bad information. He is a public figure, and failed to recognize or adhere to the responsibility that comes along with that.