How to teach people about vaccines

May 25 JDN 2460821

Vaccines are one of the greatest accomplishments in human history. They have saved hundreds of millions of lives with minimal cost and almost no downside at all. (For everyone who suffers a side effect from a vaccine, I guarantee you: Someone else would have had it much worse from the disease if they hadn’t been vaccinated.)

It’s honestly really astonishing just how much good vaccines have done for humanity.

Thus, it’s a bit of a mystery how there are so many people who oppose vaccines.

But this mystery becomes a little less baffling in light of behavioral economics. People assess the probability of an event mainly based on the availability heuristic: How many examples can they think of when it happened?

Precisely because vaccines have been so effective at preventing disease, we have now reached a point where diseases that were once commonplace are now virtually eradicated. Thus, parents considering whether to vaccinate their children think about whether they know anyone who has gotten sick from that disease, and they can’t think of anyone, so they assume that it’s not a real danger. Then, someone comes along and convinces them (based on utter lies that have been thoroughly debunked) that vaccines cause autism, and they get scared about autism, because they can think of someone they know who has autism.

But of course, the reason that they can’t think of anyone who died from measles or pertussis is because of the vaccines. So I think we need an educational campaign that makes these rates more vivid for people, which plays into the availability heuristic instead of against it.

Here’s my proposal for a little educational game that might help:

It functions quite similarly to a classic tabletop RPG like Dungeons & Dragons, only here the target numbers are based on real figures.


Gather a group of at least 100 people. (Too few, and the odds become small enough that you may get no examples of some diseases.)

Each person needs 3 10-sided dice. Preferably they would be different colors or somehow labeled, because we want one to represent the 100s digit, one the 10s digit, and one the 1s digit. (The numbers you can roll thus range uniformly from 0 to 999.) In TTRPG parlance, this is called a d1000.

Give each person a worksheet that looks like this:

DiseaseBefore vaccine: Caught?Before vaccine: Died?After vaccine: Caught?After vaccine: Died?
Diptheria



Measles



Mumps



Pertussis



Polio



Rubella



Smallpox



Tetanus



Hep A



Hep B



Pneumococca



Varicella



In the first round, use the figures for before the vaccine. In the second round, use the figures for after the vaccine.

For each disease in each round, there will be a certain roll that people need to get in order to either not contract the disease: Roll that number or higher, and you are okay; roll below it, and you catch the disease.


Likewise, there will be a certain roll they need to get to survive if they contract it: Roll that number or higher, and you get sick but survive; roll below it, and you die.

Each time, name a disease, and then tell people what they need to roll to not catch it.

Have them all roll, and if they catch it, check off that box.

Then, for everyone who catches it, have them roll again to see if they survive it. If they die, check that box.

Based on the historical incidences which I have converted into lifetime prevalences, the target numbers are as follows:

DiseaseBefore vaccine: Roll to not catchBefore vaccine: Roll to surviveAfter vaccine: Roll to not catchAfter vaccine: Roll to survive
Diptheria138700
Measles244100
Mumps66020
Pertussis1232042
Polio208900
Rubella191190
Smallpox201200
Tetanus1800171
Hep A37141
Hep B22444
Pneumococca1910311119
Varicella95011640

What you should expect to see for a group of 100 is something like this (of course the results are random, so it won’t be this exactly):

DiseaseBefore vaccine: Number caughtBefore vaccine: Number diedAfter vaccine: Number caughtAfter vaccine: Number died
Diptheria1000
Measles24000
Mumps7000
Pertussis12100
Polio2000
Rubella2000
Smallpox2000
Tetanus0000
Hep A4000
Hep B2000
Pneumococca2111
Varicella950160

You’ll find that not a lot of people have checked those “dead” boxes either before or after the vaccine. So if you just look at death rates, the difference may not seem that stark.

(Of course, over a world as big as ours, it adds up: The difference between the 0.25% death rate of pertussis before the vaccine and 0% today is 20 million people—roughly the number of people who live in the New York City metro area.)

But I think people will notice that a lot more people got sick in the “before-vaccine” world than the “after-vaccine” world. Moreover, those that did get sick will find themselves rolling the dice on dying; they’ll probably be fine, but you never know for sure.

Make sure people also notice that (except for pneumococca), if you do get sick, the roll you need to survive is a lot higher without the vaccine. (If anyone does get unlucky enough to get tetanus in the first round, they’re probably gonna die!)

If anyone brings up autism, you can add an extra round where you roll for that too.

The supposedly “epidemic” prevalence of autism today is… 3.2%.

(Honestly I expected higher than that, but then, I hang around with a lot of queer and neurodivergent people. (So the availability heuristic got me too!))

Thus, what’s the roll to not get autism? 32.

Even with the expansive diagnostic criteria that include a lot of borderline cases like yours truly, you still only need to roll 32 on this d1000 to not get autism.

This means that only about 3 people in your group of 100 should end up getting autism, most likely fewer than the number who were saved from getting measles, mumps, and rubella by the vaccine, comparable to the number saved from getting most of the other diseases—and almost certainly fewer than the number saved from getting varicella.

So even if someone remains absolutely convinced that vaccines cause autism, you can now point out that vaccines also clearly save billions of people from getting sick and millions from dying.

Also, there are different kinds of autism. Some forms might not even be considered a disability if society were more accommodating; others are severely debilitating.

Recently clinicians have started to categorize “profound autism”, the kind that is severely debilitating. This constitutes about 25% of children with autism—but it’s a falling percentage over time, because broader diagnostic criteria are including more people as autistic, but not changing the number who are severely debilitated. (It is controversial exactly what should constitute “profound autism”, but I do think the construct is useful; there’s a big difference between someone like me who can basically function normally with some simple accommodations, and someone who never even learns to talk.)

So you can have the group do another roll, specifically for profound autism; that target number is now only 8.

There’s also one more demonstration you can do.

Aggregating over all these diseases, we can find the overall chance of dying from any of these diseases before and after the vaccine.

Have everyone roll for that, too:

Before the vaccines, the target number is 8. Afterward, it is 1.

If autism was brought up, make that comparison explicit.

Even if 100% of autism cases were caused by vaccines (which, I really must say, is ridiculous, as there’s no credible evidence that vaccines cause autism at all) that would still mean the following:

You are trading off a 32 in 1000 chance of your child being autistic and an 8 in 1000 chance of your child being profoundly autistic, against a 7 in 1000 chance of your child dying.

If someone is still skeptical of vaccines at this point, you should ask them point-blank:

Do you really think that being autistic is one-fifth as bad as dying?

Do you really think that being profoundly autistic is as bad as dying?

Argumentum ab scientia is not argumentum baculo: The difference between authority and expertise

May 7, JDN 2457881

Americans are, on the whole, suspicious of authority. This is a very good thing; it shields us against authoritarianism. But it comes with a major downside, which is a tendency to forget the distinction between authority and expertise.

Argument from authority is an informal fallacy, argumentum baculo. The fact that something was said by the Pope, or the President, or the General Secretary of the UN, doesn’t make it true. (Aside: You’re probably more familiar with the phrase argumentum ad baculum, which is terrible Latin. That would mean “argument toward a stick”, when clearly the intended meaning was “argument by means of a stick”, which is argumentum baculo.)

But argument from expertise, argumentum ab scientia, is something quite different. The world is much too complicated for any one person to know everything about everything, so we have no choice but to specialize our knowledge, each of us becoming an expert in only a few things. So if you are not an expert in a subject, when someone who is an expert in that subject tells you something about that subject, you should probably believe them.

You should especially be prepared to believe them when the entire community of experts is in consensus or near-consensus on a topic. The scientific consensus on climate change is absolutely overwhelming. Is this a reason to believe in climate change? You’re damn right it is. Unless you have years of education and experience in understanding climate models and atmospheric data, you have no basis for challenging the expert consensus on this issue.

This confusion has created a deep current of anti-intellectualism in our culture, as Isaac Asimov famously recognized:

There is a cult of ignorance in the United States, and there always has been. The strain of anti-intellectualism has been a constant thread winding its way through our political and cultural life, nurtured by the false notion that democracy means that “my ignorance is just as good as your knowledge.”

This is also important to understand if you have heterodox views on any scientific topic. The fact that the whole field disagrees with you does not prove that you are wrong—but it does make it quite likely that you are wrong. Cranks often want to compare themselves to Galileo or Einstein, but here’s the thing: Galileo and Einstein didn’t act like cranks. They didn’t expect the scientific community to respect their ideas before they had gathered compelling evidence in their favor.

When behavioral economists found that neoclassical models of human behavior didn’t stand up to scrutiny, did they shout from the rooftops that economics is all a lie? No, they published their research in peer-reviewed journals, and talked with economists about the implications of their results. There may have been times when they felt ignored or disrespected by the mainstream, but they pressed on, because the data was on their side. And ultimately, the mainstream gave in: Daniel Kahneman won the Nobel Prize in Economics.

Experts are not always right, that is true. But they are usually right, and if you think they are wrong you’d better have a good reason to think so. The best reasons are the sort that come about when you yourself have spent the time and effort to become an expert, able to challenge the consensus on its own terms.

Admittedly, that is a very difficult thing to do—and more difficult than it should be. I have seen firsthand how difficult and painful the slow grind toward a PhD can be, and how many obstacles will get thrown in your way, ranging from nepotism and interdepartmental politics, to discrimination against women and minorities, to mismatches of interest between students and faculty, all the way to illness, mental health problems, and the slings and arrows of outrageous fortune in general. If you have particularly heterodox ideas, you may face particularly harsh barriers, and sometimes it behooves you to hold your tongue and toe the lie awhile.

But this is no excuse not to gain expertise. Even if academia itself is not available to you, we live in an age of unprecedented availability of information—it’s not called the Information Age for nothing. A sufficiently talented and dedicated autodidact can challenge the mainstream, if their ideas are truly good enough. (Perhaps the best example of this is the mathematician savant Srinivasa Ramanujan. But he’s… something else. I think he is about as far from the average genius as the average genius is from the average person.) No, that won’t be easy either. But if you are really serious about advancing human understanding rather than just rooting for your political team (read: tribe), you should be prepared to either take up the academic route or attack it as an autodidact from the outside.

In fact, most scientific fields are actually quite good about admitting what they don’t know. A total consensus that turns out to be wrong is actually a very rare phenomenon; much more common is a clash of multiple competing paradigms where one ultimately wins out, or they end up replaced by a totally new paradigm or some sort of synthesis. In almost all cases, the new paradigm wins not because it becomes fashionable or the ancien regime dies out (as Planck cynically claimed) but because overwhelming evidence is observed in its favor, often in the form of explaining some phenomenon that was previously impossible to understand. If your heterodox theory doesn’t do that, then it probably won’t win, because it doesn’t deserve to.

(Right now you might think of challenging me: Does my heterodox theory do that? Does the tribal paradigm explain things that either total selfishness or total altruism cannot? I think it’s pretty obvious that it does. I mean, you are familiar with a little thing called “racism”, aren’t you? There is no explanation for racism in neoclassical economics; to understand it at all you have to just impose it as an arbitrary term on the utility function. But at that point, why not throw in whatever you please? Maybe some people enjoy bashing their heads against walls, and other people take great pleasure in the taste of arsenic. Why would this particular self- (not to mention other-) destroying behavior be universal to all human societies?)

In practice, I think most people who challenge the mainstream consensus aren’t genuinely interested in finding out the truth—certainly not enough to actually go through the work of doing it. It’s a pattern you can see in a wide range of fringe views: Anti-vaxxers, 9/11 truthers, climate denialists, they all think the same way. The mainstream disagrees with my preconceived ideology, therefore the mainstream is some kind of global conspiracy to deceive us. The overwhelming evidence that vaccination is safe and (wildly) cost-effective, 9/11 was indeed perpetrated by Al Qaeda and neither planned nor anticipated by anyone in the US government , and the global climate is being changed by human greenhouse gas emissions—these things simply don’t matter to them, because it was never really about the truth. They knew the answer before they asked the question. Because their identity is wrapped up in that political ideology, they know it couldn’t possibly be otherwise, and no amount of evidence will change their mind.

How do we reach such people? That, I don’t know. I wish I did. But I can say this much: We can stop taking them seriously when they say that the overwhelming scientific consensus against them is just another “appeal to authority”. It’s not. It never was. It’s an argument from expertise—there are people who know this a lot better than you, and they think you’re wrong, so you’re probably wrong.