Vaccinations, global warming, and the fork in the canning jar

Images: Global Warming Predictions Map, Robert Rohde, CC BY-SA 3.0 via and (Business-as-usual projection, 3ºC average warming. Jars of mango chutney: Photo (and chutney) by Stephen Heard.

Do you cringe when someone asserts that vaccines cause autism, or that global warming isn’t happening? I do. I’m a scientist, and like most of my colleagues, I think of this not just as a 9-to-5 job but also as a way of thinking about the world around me. So, at least in my mental picture of myself, when I have a choice to make, I quantify and tot up advantages and disadvantages of each option* and come to a reasoned decision. When I don’t know something, I look for answers in the scientific literature. When it turns out that nobody knows that something, I have a set of approaches to fill the gap – experiments and models and statistics and the rest (and I can deploy this scientific toolkit in writing and cooking and doing laundry every bit as much as I can in matters more traditionally scientific). In short, I picture myself as a rational being – and this is probably why antivaxxers, climate-change denialists, and their irrational brethren drive me bananas.


chutney smallI make a mean mango chutney (I promise there’s a connection). Every six months or so I spend a day in a kitchen redolent of vinegar and spices, chopping and simmering and canning. And for many years I sterilized my canning jars exactly the same way that I helped my mother do it when I was growing up. I’d fill the sink with empty jars, boil a big kettleful of water, and then carefully place a fork in each jar before pouring in the boiling water to sterilize. Why the fork, you ask? Well, because (my mother assured me), if you don’t put the fork in, then the boiling water can crack the jars. So, year after year, jar after jar, in went the fork; and sure enough, I never cracked a jar.

But just last year, I stopped and thought about the fork – and with even a little scientific thought, it’s shockingly obvious that putting a fork in the jar can’t possibly affect its chances of cracking. The physics just isn’t there: the heat content of 500 mL of boiling water is orders of magnitude higher than the heat that can be conducted away in a split second by a single fork. So I put away the fork.

What does the fork in the canning jar have to do with global warming? Well, as much as I like to think of myself as a rational creature with a scientific worldview, I spent years putting forks in jars. Human brains have psychology, and in many cases that psychology works against the kind of rational thinking I’d like to see everyone use. We’re really good, for example, at inferring process from small flashes of pattern (which is why we see faces on Mars, and why we still need the P-value). We also have strong confirmation bias, which is why my long run of uncracked jars reinforced my (foolish) fork usage.

So when a non-scientist dismisses global warming because their home town had a cold winter, or fears vaccination because a nephew got sick right after his shots, perhaps we shouldn’t be quite so derisive. Their inference is mistaken (vaccines don’t cause autism, but do save lives; and global warming is real and an enormous threat**), but it’s mistaken in ways that are quite natural given human psychology. After all, I’m a scientist and I like to believe I think scientifically, but I make the same mistakes – albeit about forks and boiling water, instead of global warming and vaccines.

If it seems like I’m giving antivaxxers and climate-change denialists a free ride, it may be because I haven’t yet drawn what I think is a critical distinction. For non-scientists just coming to their own conclusions, our correct reaction to unscientific thinking is understanding and explanation, not derision. But the moment non-scientists move beyond their own conclusions, things change. For those who blog or teach antivaxx or who apply antivaxx thinking to their children’s healthcare, or those who question global warming in the classroom, while running for office, owning a media outlet, or running an oil company, it’s hard to overdo the scorn.

Why the distinction? Because as soon as you take the step from holding a belief to promulgating that belief, or to acting on that belief with consequences for others, you take on an ethical responsibility to know that that belief is correct*** (and the system that lets us check whether a belief is correct is, of course, science). My fork in the canning jar was foolish but harmless; but if I offered a course in safe canning and based my curriculum entirely on stuff my mother said, I hope you’d all tell your friends to stay away. Similarly, if you make public statements or advocate actions about vaccines or global warming without reasoning scientifically or deferring to modern scientific consensus, you’re behaving unethically, or you’re an idiot, or quite possibly both****.

So the real modern scandal isn’t the polling data that show widespread public misunderstanding of how the world works. True, those numbers are disheartening (just for instance, 20% of Ontarians believe vaccines cause autism, 33% of Americans believe there won’t be global warming during their lifetimes, and don’t get me started on evolution), but they aren’t scandalous. What is scandalous is the eagerness of some people to encourage public ignorance – for ideological reasons, for economic ones, or just for the love of hearing themselves blather.

So, is the average climate-change denialist stupid? No, just human. But that’s no excuse for those who prey upon that humanity. Shame on them.

© Stephen Heard ( January 5, 2016

(Tenuously) related posts:

*^Although I’m not sure I’d take this as far as Charles Darwin deciding whether or not to get married.

**^Which you knew, of course, but I felt the need to stick that in there so I’m covered after somebody quotes me out of context.

***^Or at least “consistent with the current state of human knowledge”, but “correct” is a lot shorter, so I’ll use that.

****^Not least if your unrelated celebrity gives you a voice people listen to, and yes, I’m talking about you, Jenny McCarthy, Rob Schneider, and Jim Carrey.


12 thoughts on “Vaccinations, global warming, and the fork in the canning jar

  1. jeffollerton

    I told that Darwin marriage anecdote in my after-dinner speech at our wedding in August, but much edited, including leaving out the “better than a dog” line 🙂 Karin said she would have found it funny but I suspect some of our other guests wouldn’t have seen the humour!

    Liked by 1 person

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