Guest article written by Holly Vesco.

We’ve all heard the question, and perhaps even asked it ourselves, “Just how do scientists know that?” The question is innocent enough, but all too often it’s asked with a sense of distrust and even with a touch of condescension. Honestly, with or without the skepticism, it’s a question worth asking and answering.

It’s perfectly fine to ask how science knows what it knows and to have a desire to understand how the evidence supports the conclusions scientists come to. Those kind of questions are actually a large part of what peer-review does. The type of skepticism that I take issue with (the kind this article is addressing) is different, it doesn’t allow people to follow the facts, but to distort the them to fit their previously held beliefs. This way of thinking turns the question “how can they know that?” into a declaration of “they can’t know that!” That version of skepticism is not true skepticism, but instead it’s just a fancy way of saying, “I don’t like it, so it’s not true.”

Imagine you’re a parent and a friend asks you if your child likes applesauce; you think about it, and while your kid has never said they don’t like applesauce, they’ve also never asked for it. You continue to reflect on the question, and you realize that your kid refuses to eat it, and will take any other option over applesauce. You conclude, based on your child’s eating habits, that they do not like applesauce. So, you tell your friend “no”. Instead of your friend trusting that your knowledge of your own kid is sufficient enough to give an accurate response, your friend responds, “How can you know that? You can’t know that your kid doesn’t like applesauce!” They continue “Have you tried feeding them every kind? You just don’t like applesauce and are just trying to discriminate against me because I love it!”

This response would not only shock you, but it would be insulting. No, you don’t know every single thing about your child, but you don’t need to in order to answer this question. You’ve ‘studied’ your kid throughout their life enough to know that all the signs point to them not liking apple sauce. This may seem like a crazy scenario, but it is very similar to what scientists are faced with in the public arena. Their work is questioned, dismissed, and ridiculed by those who are not trained in their field. Their research is commonly rejected by the public because it calls into question deeply held personal beliefs

Our cultural climate presents us with an interesting dichotomy; we rely on science but don’t want to trust it when our beliefs are challenged by it. Sure, science is great when it keeps us from dying of cancer or when it allows us to play fun games on our fancy phones, but when science shows that we’re changing the planet’s climate, or that we are decedents of other primates, all of sudden it can’t be trusted. So, why should we put our trust in scientists? How do they know what they know? The answer is simply this: they study it and follow the evidence.

Scientists are not a group of people in lab coats who just throw out whatever idea they like the best and declare it as truth. They aren’t part of a worldwide conspiracy to get you to believe in climate change so you’ll end up driving a Prius to get some organic tofu. Sadly, as organized as science is, to quote Naomi Oreskes, “Scientists aren’t that organized” (emphasis mine). Science is driven, not by opinions, but by the scientific method.

The scientific method is powerful tool that allows science to be self-correcting and remove as much personal bias as possible. Scientists can’t just spew forth whatever they want to be true and make the evidence fit the “theory.” Science is a rigorous process of making observations, formulating a hypothesis, testing that hypothesis, drawing conclusions and presenting them to your peers to be tested and retested. We formulate the hypothesis based on what the evidence tells us and maybe if we’re lucky it will become a theory.

A hypothesis only becomes a scientific theory when it has been repeatedly tested and confirmed through experimentation and observation. Scientists are forced to reject what the facts don’t support. It’s that simple.

Sometimes the conclusions of a study show a previously held position was wrong, sometimes the results confirm an already well established position. The simple fact is that scientists know what they know because they have received training to judge the complex pieces of evidence we have and draw conclusions based on that. A person can’t just put on a lab coat and call themselves a biologist; they spend years learning everything they can about biology, and how to research biology.

Science isn’t out to destroy your world-view. Science doesn’t care what you believe, science cares about what the evidence says. So when the question is asked, “and just how do scientists know that?” You can answer, “Because they’ve studied it, they have researched the facts, and they have formed their answers based on what the research says. That’s how they know.”

Holly Vesco holds a degree in General Science and has been involved in science education outreach with her community for several years. She has aided in Archaeoastronomy field research, and is currently pursuing a graduate degree in Physics with a long term goal of earning a PhD in Astrophysics.