Scientific Uncertainty

Science is a wonderful system of knowledge, discovery, and invention. It’s brought us things like not dying before age five, heart transplants, and those little plastic fish we keep soy sauce in before it goes on sushi.

And as a society, we put science on an enormous pedestal. It can be wild and outlandish, it can be strange and unusual, but if scientists have investigated the question and found it to be true then it’s suddenly a fact. We give a credence to the journey of scientific discovery that we don’t give to any other system of thought, because science deals in facts. It relates directly to truth.

But if that’s true, why are scientists never sure of anything?

Let’s talk a little bit about scientific uncertainty.

History of Science

We like to think of science as a monolith that has always existed, but the reality is that much of what we now think of as scientific was developed only a few centuries ago. The ubiquitous white lab coat, for example, only came into being in the 1800s.

Similarly, the love of deductive reasoning, the essential skepticism, and most other hallmarks of scientific inquiry are actually younger than you might think. Prior to the 1600s, people thought absolute truth was the way to go. It wasn’t until the time of Descartes — the French guy who said “I think, therefore I am”, and whose skull toured Europe after his death — that scientists really started embracing the idea that there may be no absolute truths out there to find.

And yet, somehow, we still get told scientific facts. Water is made of hydrogen and oxygen, carbon dioxide is a greenhouse gas, humans are one of the only mammalian species that doesn’t have a penis bone called the os penis*.

Which brings us to the reason for this blog — scientific uncertainty.

Being Uncertain

Uncertainty is something of an open secret in science. Ask any scientist if they’re certain that their finding is correct, and they’ll pause, think, and reply: “As certain as I can be”.

This is no mistake.

The thing about science is that we can rarely demonstrate things to be absolutely true. We may have good evidence for something, may be able to demonstrate it time and again, but sometimes even then the truth is different.

For example, we know that paracetamol — Panadol , Tylenol, acetaminophen— can help with pain. It’s among the most commonly used pain killer in the world. For decades, paracetamol has been considered a first-line treatment for lower back pain, because of its low side-effect profile and efficacy.

And yet, when we look at whether it works for lower back pain, the evidence just isn’t there. Even though we now have really good, big studies looking at the problem, we’ve been unable to demonstrate an effect. The best evidence to date — which is really very good — shows that paracetamol doesn’t do anything at all to help with lower back pain.

Even our truths sometimes aren’t.

Embracing Uncertainty

Now, I know what will happen next. Some evolutionary backwater will take this blog and hold it up and say “Ah-ha! Scientists don’t know anything! You can ignore your doctors and listen to me”.

This is total nonsense and not what I’m saying at all. Listen carefully.

Science is inherently uncertain. That doesn’t mean it’s completely free of knowledge. You may not ever be able to be 100% sure of any scientific finding (or anything, really), but you can get very close.

This is where expertise (and good science communication) comes in. Take the recent headlines about sugar giving you cancer. This is a single study looking at an incredibly complex question full of confounding factors. The reality is that interpreting the results of this study requires a good understanding of statistics, and at least some grasp of epidemiology and medicine.

We can’t know for sure if sugar is causing cancer — for the record, I don’t think that this study demonstrates that it is, even though it’s a really spectacular piece of research. But what we can do is draw reasonable conclusions, based on cautious interpretations of previous experiments, to say that there’s a good chance that sugar could be bad for your health and even if it isn’t causing cancer directly it’s probably a good idea to have less of it anyway.

Which is, funnily enough, basically what the scientists concluded in the study itself.

This is the real story of science — gradual accumulation of knowledge that lies behind every fact that you know. Are we certain that bacteria cause bacterial infections? No. But we have overwhelming, incontrovertible evidence that they do. For it not to be true we’d have to have been wrong in almost every way imaginable since at least the late 1800s if not before.

We all want science to be easy, because no on wants things to be hard, but it so rarely is. We want simple, digestible fact, when the reality is that most things are very hard to answer.

Are artificial sweeteners bad for you? Depends on what you’re comparing them to. Is RoundUp causing cancer? Probably not, but it depends on who you are. Science is filled with prevarication, because we can be very confident of things but never totally sure.

The point here is not that all science is wrong. The point is that pedestals are rare, and most scientific discoveries are just as flawed as any human knowledge.

The only real choice is to embrace uncertainty, know that you may never know anything for sure, and realize that it doesn’t matter anyway. We rarely make decisions based entirely on science, because we aren’t unfeeling machines. Truly understanding an issue and making a choice can take a lot of time and expertise — although good science communication can go a long way —but realistically we make choices in our lives for a diverse range of reasons only a few of which are evidence-based.

The real take-home here is that any time someone tries to tell you the science is simple, they’re probably wrong.

Be a scientist: embrace the uncertainty, and come up with a conclusion anyway.

And sometimes, you’ll be left with more questions than answers.

That’s just the way that science works.

P.s. in case this wasn’t clear — listen to your doctors, they know a hell of a lot more than most people about health specifically so that they can treat you.

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*Note: yes, really.