I originally wrote this article in 2014 to discuss whether correlation implies causation. Not that I expect everyone to read and remember this one article, but it’s frustrating when I see a conversation where people who deny science and accept science both misuse correlation and how it relates to causation. So, I decided to update this article and republish it as a reminder that the relationship of correlation to causation isn’t as easy as a simple trope or meme.
One of the foundations of biomedical science is whether correlation implies causation. Anti-vaccine activists often conflate or misunderstand the two, rejecting or accepting correlation as it fits its narrative. The “correlation implies causation” story is often abused, misused and confused by many writers.
One thing we do know about correlation is that if you can’t establish correlation, despite numerous attempts, it is nearly impossible to claim causation. Also, if you do observe correlation, it also doesn’t imply causation.
But there are methods, grounded in powerful science, to establish causation from observations of correlation. So sometimes correlation does not imply causation. But sometimes correlation implies causation.
I am an admitted coffee aficionado. I love the taste. I love the warmth. No, I don’t drink those maddening caramel strawberry double shot nonfat iced frappucinos – I like my coffee hot with a splash of cream and some very safe aspartame. Nevertheless, I’ve never thought much about coffee health advantages – it never seemed relevant to me.
I remember directing a clinical trial at a large teaching hospital in Seattle, WA back in the late 1980s, and there was a Starbucks kiosk in the lobby. I know most of you would think “what’s so great about that?” But, it was nearly 30 years ago, and Starbucks wasn’t a thing that it is today – I know some coffee snobs hate them, but 30 years ago, good coffee was unknown to most of the USA. Well, unless you lived in Seattle, apparently.
That kiosk started my love of coffee. I tried different coffee makers and methods of brewing coffee. Over the years, I’ve settled on a French press (as it is known in Canada and the USA, a coffee plunger in Australia and New Zealand, or a cafetière in France and the UK) for my coffee, which probably makes me a coffee snob.
When dealing with those pushing pseudoscience, like the antivaccination cult, the most frustrating thing is that they tend to ignore and deny the most basic tenets of science. If denying the fact of gravity would further their goals of “proving” vaccines are neither effective nor safe, they would do so. And now that it’s flu season, they’re producing zombie tropes about flu vaccine ingredients.
If the antivaccination movement didn’t lead to epidemics of long-gone diseases, which can harm and kill children, the conversation would be over. I would just put the vaccine deniers in the same group as evolution deniers (creationists) or gravity deniers (there has to be some, somewhere). I would mock their pseudoscience, and move on. Of course, their denialism does lead to deaths of children, so we have to do what is right, and stop their lies, misinformation and ignorance in every forum we can.
We have to appeal to scientific values, and despite the fact that antivaccination pushers don’t share those values, we must continue to try. I have gotten enough emails and comments from people that they have started to vaccinate because of what I have written, so maybe some child’s life is better because all of us who support vaccines are heard.
If you spend any amount of time on the internet researching science and pseudoscience, you’ll find alarming claims about toxic or poisonous substances in our foods, vaccines, air, water, and so much else. And then you’ll find a lot of people (myself included) who try to present science-based evidence that these substances are neither toxic nor poisonous.
Paracelsus, a 16th century Swiss German physician, alchemist, astrologer, is traditionally thought to have founded the discipline of toxicology, an important branch of medicine, physiology, and pharmacology. Paracelsus wrote one of the most important principles of toxicology:
All things are poisons, for there is nothing without poisonous qualities. It is only the dose which makes a thing poison.
In other words, if you’re speaking about substances in foods or vaccines or anything, the most important principle is that the dose makes the poison (or toxin). Everything that we can consume or breathe is potentially toxic, but what is the most overriding principle must be the dose. Continue reading “Simple math – the dose makes the poison”