When dealing with anti-vaccers and other believers in woo, I often encounter indignant parents who, when faced with evidence and arguments that are contrary to their views, respond with, “well as a parent, only I know what is best for my child.” This sentiment is pervasive among anti-vaccers, but if we think about it for even a few seconds, the absurdity of it quickly becomes clear. Giving birth clearly does not magically impart you with infinite medical knowledge. Having a child is not even remotely equivalent to earning a medical degree. It’s kind of unbelievable that I even have to say that, but apparently, I do.

The problems with this claim should become obvious as soon as we start applying it to other situations. For example, purchasing a computer clearly does not endow me with instant and incomparable knowledge about anti-virus software, firewalls, etc. Similarly, no one claims to be an expert mechanic by sheer virtue of the fact that they own a car, so why would we think that simply having a child makes someone a medical expert?

I want to take that car analogy a bit further, because I think it is instructive. Imagine that I have decided that the notion that you need to do regular oil changes to protect your engine is actually just a conspiracy by car companies to make money, and, in fact, not only is it fine to never change your oil, but oil changes are actually bad for your car. Obviously, that position is absurd, but now imagine that you confronted me about it, and I responded by saying, “well as the owner of my car, only I know what is best for it.” Would you accept that response? Would it instill you with confidence that I actually know what I am talking about? I doubt it. It would be obvious to you that the fact that I own a car has no bearing on the extent of my mechanical knowledge, and plenty (probably most) car owners know next to nothing about mechanics. Nevertheless, that is exactly what anti-vaccine parents do. They hold a dangerous position that is discredited by a mountain of evidence, yet they feel justified in their position simply because they have a child.

Now, at this point, someone may accuse me of a straw man fallacy, and argue that giving birth doesn’t magically give you medical knowledge, but rather, parents know best because they are the ones who interact with their child on a daily basis and know the most about him/her. That argument isn’t really any better though. Watching your child on a daily basis can’t possibly give you knowledge about your child’s internal physiology, nor can it inform you about the results of carefully controlled studies. Interacting with your child can’t magically inform you that vaccines are dangerous, for example. Going back to my car example, I could say that as the owner of the car, I am the one who interacts with it on a daily basis and know the most about it, but that clearly doesn’t make me any less wrong about the necessity of oil changes. In other words, interacting with your child doesn’t magically give you medical knowledge any more than driving my car magically gives me mechanical knowledge. To be clear, parents should report their observations to a doctor when they take the child for a medical visit, just as I should report observations about the way my car drives when I take it for a tune up, but that is a far-cry from parents being in a position to reject countless medical studies simply because they have daily encounters with their progeny.

Nevertheless, a parent might try to expand on this with specific observations. For example, they might say, “well after the first shot, I could see a difference in my child, so I’ll never vaccinate again” (see note). That is, however, simply an anecdote, and it is utterly worthless for establishing causation. For one thing, personal observations are often biased, and humans are notoriously bad at deciphering trends without the aid of actual data. Further, two things often occur together just by chance. For example, in a previous post, I ran the math on autism rates and vaccination rates and showed that even though vaccines don’t cause autism, we expect there to be thousands of cases each year where, just by chance, the first signs of autism are noticed shortly after vaccination. To return to my car example again, imagine that I had an oil change once, and shortly afterwards, one of my spark plugs stopped working and had to be replaced. Could I say that since it happened right after the oil change, the oil change must have been the cause? Obviously not. Further, the fact that I am the owner of the car would still be irrelevant. I couldn’t say, “well I own the car and drive it daily, so I know what happened, and I know the oil change killed the spark plug.” That would obviously be insanity.

Note: To clarify, I am not talking about things for which causation has already been established (e.g., an immediate allergic reaction). Rather, I am talking about all the countless things that anti-vaccers attribute to vaccines, despite a total lack of evidence to support causation, and often a substantial amount of evidence against causation. Autism is a prominent example, but I have seen parents accuse vaccines of everything that you can imagine. According to them, restlessness = vaccine injury, change in food preference = vaccine injury, change in favorite toy = vaccine injury, etc. all “supported” by the notion that as parents, they surely must know what is going on with their child. It’s also worth pointing out that for the vast majority of things that anti-vaccers accuse vaccines of, there is simply no plausible causal mechanism, and they really are no different from me accusing an oil change of killing a spark plug.

Next, someone might try to appeal to “parental instincts,” but that is really just a restatement of where we started. We are back to the notion that being a parent automatically gives you medical knowledge, even thought it clearly doesn’t. As a friend of mine likes to say, parental instincts tell you that you shouldn’t let your kid play in that shady-looking guy’s van, but they can’t tell you whether or not vaccines are safe, whether or not a treatment works, etc. Only carefully controlled studies can do that.

Finally, someone will almost certainly argue that “doctors sometimes make mistakes.” This claim is, of course, true, but the fact that doctors aren’t perfect doesn’t automatically make parental instincts superior. Doctors are human, and humans make mistakes, but someone with a decade of advanced training and years of experience is far less likely to make a medical mistake than someone with no training or experience who is basing their views off gut instincts and Youtube videos (note: read this post before bringing up the claim that medical errors are the third leading cause of death).

In conclusion, I want to be clear that I’m not attacking parents or trying to “diminish” parenthood or any other such nonsense. I’m just trying to get people to have an accurate view of their own limitations. Having a child does not make you a medical expert nor does it make you the most qualified person to understand or assess your child’s health. If it did, there would be no need for doctors or science.