“Scientific Proof”: Evidence and the Scientific Method

“Scientific Proof”: Evidence and the Scientific Method

Scientific proof

Zero gravity

A perfect system of government

$3 bills

Unicorns

What do those all have in common? You guessed it… they don’t exist.

What do you mean, “Scientific proof doesn’t exist”?

We hear claims all the time about something being “scientifically proven.” The reality is, though, that science does not prove anything. That is not how science works.

Everything in science is based on the best available evidence. A long time ago, some really smart people realized, the “best available evidence” changes over time. Those smart people developed what we now call the scientific method—Francis Bacon usually gets the credit and he was most likely the first person to apply that label, but scientists and philosophers were using the method for quite a while before Frank decided to write it down and give it a name.

Let’s review the scientific method

The scientific method is arguably the best method we’ve ever come up with to understand what’s true and what’s not. We can use it in just about any field—despite the name, it’s not exclusive to science.

It’s fairly simple, too.

It starts with an observation, e.g. “objects fall to the ground when dropped.”

Then, a question: “Why do things always fall down and never up? or sideways?”

Free-fall

Next, we need a hypothesis. In simpler terms, we make a guess. Hypothesis sounds more scientific, but it’s really just a guess. Here’s one: “There is a universal ‘down’ direction and all objects are naturally drawn in that direction.”

You probably remember all of this from grade-school science (except for my ridiculous hypothesis).

You might remember the next step being, to conduct an experiment. But that’s leaving out something important. We need to make a prediction in the form, “If this hypothesis is correct, then…”

Considering my “universal down” hypothesis, I might predict that, if there’s a “universal down,” then objects in the sky would also have to move in that same direction.

Now if you’re thinking back to grade school and trying to imagine an appropriate experiment, you’re placing an unnecessary limit on the scientific method. It’s a simplification, and it’s how hypotheses are often tested, but an experiment isn’t always required. Testing the prediction is what matters.

An experiment can be designed to test predictions, but sometimes predictions are tested naturally without any human intervention. In this example, we can observe the stars in the sky. When tracking the movement of the stars, we can see that they follow a circular path relative to our position on Earth.

Circular star trails

With that simple observation, my hypothesis is falsified.

So we rinse and repeat.

Note: Yes, I know there are a lot more variables that we’d have to consider if that were a legitimate hypothesis. I confess… I’m not great at analogies.

A hypothesis can only be disproved

When the prediction fails, we start over. It has been shown to be wrong.

If we found that the prediction was correct, though, it only supports the hypothesis. It does not prove it to be correct. If we had observed stars to all move in one direction, and it appeared that they all moved toward Earth, we could say, “That fits with the ‘universal down’ hypothesis. Let’s make another prediction and see if it still holds up.”

With each prediction that is satisfied, we can be more confident that our hypothesis is correct. But we can never say that it is proven.

Isaac NewtonI’ll continue using gravity as an example. Isaac Newton developed the original gravitational theory in which he said that all mass attracts all other mass, and that the force of attraction is proportional to the product of the masses divided by the square of the distance between them. Mathematically, it looks like this:

F∝m1m2/R2

We still use that theory today, and in almost every case, it works. It has satisfied thousands, perhaps millions of predictions. But, in certain extreme cases, it breaks down.

Fortunately, Einstein proposed an even better theory that we know as general relativity—as well as Newtonian gravity works, and as useful as it is even now, Einstein’s general relativity is even better supported than Newton’s explanation of gravity. If we decided that Newton proved his theory of gravity, we might have stopped looking.

We now know that Einstein’s theories aren’t perfect, either. They’re damn good, but there are still very extreme cases where Einstein’s equations fail. Eventually, another really smart person or group of smart people will develop an even better theory of gravity. That is how science works.

But it’s just easier to say “It’s scientifically proven”!

In regular conversation, we call things “proven” all the time. Even scientists say it in casual conversation.

For the most part, that’s fine. Consider it a colloquial use of the word. People often use the word “theory” when what they really mean is “idea” or “wild-ass guess,” and those are very different from what the word means in a scientific context. Similarly, if someone says a scientific concept is “proven,” take it to mean that the evidence very strongly supports it. That is the more correct phrasing, but we all speak in colloquialisms much of the time—even scientists.

Saying that a scientific theory has been proven isn’t exactly accurate, but it’s usually close enough. Established scientific theories are the closest we have to absolute facts in science, but they are not “scientifically proven.” Science does not prove. Not ever.

If someone is telling you that their product is “scientifically proven to…” whatever, you should be suspicious. By the same token, when someone tells you that a scientific theory “has never been proven,” you can also tell them, “Neither has gravity.” And yet, it works.

So, what are your thoughts? Let me know in the comments.

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