[Updated 2/19/19]

Ever heard the expression, “Evolution is just a theory”?

It’s often used by creationists who deem the theory of evolution, an observation initially put forth by Charles Darwin in The Origin of Species, as an insult to their religion because it isn’t consistent with the accounts of the Bible, Quran, etc.

The notion that all life evolved from a single-celled organism, affectionately known as LUCA (Last Common Universal Ancestor) simply doesn’t jive with being taught that a God created man shortly after the start of time.

If you’ll indulge me for a moment, I will explain, albeit quite simplified, why that is a profoundly wrong and insulting statement to make to discredit evolution.

There are generally accepted levels that answers to questions can be given or assigned, from a scientific perspective. Since science is what brought you the theory of evolution, that’s what should be referenced when discussing it.

Because this is a simple blog post and not a thesis, think of this as just a Cliff’s notes version to explain the basic concept. So please no attacks if you think I left something important out. But by all means, feel free to chime in below if you want to add anything.

Anyway, enough babbling, here goes…

GUESS:

The lowest level assigned to the answer to a question would be a guess. A guess is when you have no evidence you are basing your guess on, you’re just picking something that seems to make the most sense to you and going with it. We all do it, there’s nothing wrong with it, but it’s just not science.

EDUCATED GUESS:

With an educated guess, you still haven’t actually gathered evidence or done any work you could call science, but now you have some knowledge that leads you to your guess so it’s not just a garden variety random guess as above.

This might also be a situation where you might ask a physicist, for example, about a question that could be answered by physics. If they don’t know the answer, yet based on what they do know, they make a guess, that’s an educated guess.

HYPOTHESIS:

For the first time, we’re talking about actually beginning to do some science.

Imagine you observe something, and you don’t know what it is or why it happened. You’ll gather evidence, try to repeat the observation if you’re able, and look for consistencies. Based on the evidence you have, you’ll form a hypothesis—a conclusion the evidence has taken you to. This is better than a guess because you’ve actually done some work to come to this conclusion, observed the thing you wish to answer first hand, and therefore your conclusion is evidence-based, not something conjured up in your imagination alone.

From there, scientists will test their hypothesis by attempting to falsify it. This means that they try to prove themselves wrong, not right. This may seem counter-intuitive at first, but allow physicist Derek Muller of Veritasium to explain. I promise, you really want to watch this video. It only takes a few minutes, but it will make you rethink the way you approach problems.

Once you’ve made every attempt to falsify your hypothesis, many scientists will attempt to publish their findings in a peer-reviewed journal, with full disclosure of their hypothesis, as well as all their testing methodologies and findings, in hopes that others will test the hypothesis and see if they come to the same conclusions. This is known as replication studies.

If replication occurs consistently, either a law or a theory typically forms.

LAW:

Once something can be fully observed and tested to a consistent result, it becomes scientific law. A law requires full observation. For instance, if I drop something from ten feet up, and see how fast it accelerates to the floor, I’ve watched the process from start to finish, and can observe it every step of the way. 

Isaac Newton’s Laws of Motion or Universal Law of Gravitation, etc. as some of the most commonly understood examples.

We understand them, we can observe them from start to finish, we know them to be consistently true, and we’re readily able to replicate the results every single time we either test them, or use them to test something else.

THEORY:

I’ll spend the most time on this one, since it’s the one in the title of this post.

A theory, in common parlance, is often stated as if it’s a guess, but in science, it is much more than that. Theories and laws are effectively the gold standard of science, since science would say there is no knowable absolute (I’ll explain later).

Whereas a law can be observed from start to finish, a theory is a much more complex hypothesis, or set of smaller hypothesis to form a larger one, which are all wholly supported by the evidence, but cannot be fully observed.

For instance, thousands of biologists doing work on the genome project, or studying different species of plants or animals, have made hundreds of thousands of small studies on thousands of smaller questions that fit into the overarching theory of evolution as proposed by Charles Darwin. If any one of them had found evidence to prove the theory of evolution wrong, and their results were replicated by reputable biologists, the theory of evolution would have ended shortly after.

Scientists have updated things Darwin guessed might be true, but was wrong about, but nothing so far has proven the basic theory of evolution by natural selection to be incorrect. But each time biologists understand more about how animals evolve, each time fossils or old animal remains are discovered, each time DNA is analyzed, the evidence that comes out of it, fits neatly into the theory of evolution.

But the reason it’s a theory and not a law, is that we cannot go back in time (at least, not with today’s technology) and observe how life started, how LUCA was formed, etc., and fully observe evolution from it’s start to today. So scientists have to piece the puzzle together with historical evidence, and observations they can make.

If I can use a simple analogy; I will compare scientific theory to a jigsaw puzzle depicting Albert Einstein. 

A theory is what the puzzle appears to depict, composed of pieces that have all been determined to specifically fit in it. That puzzle still has a few pieces missing from it you haven’t found yet (items you can’t observe), so you don’t entirely understand what the complete puzzle looks like. If the pieces depicting Einstein’s hair are missing for instance, you can still reasonably assume it’s a picture of Einstein by the face, you’re just not sure what his hair looked like at the time the picture was taken.

In science, it’s only accepted theory if no single piece has ever been proven wrong or falsified. If one piece turns out to be false, scientists must effectively scrap the whole theory, and remove any assumptions they might have made to that point about it.

In the case of evolution, there are thousands of independent studies on different aspects of evolution, most of which have been peer-reviewed, never been proven wrong or falsified, and that all consistently support the theory of evolution—each one completing a larger and larger chunk of that particular puzzle.

Just because we don’t know exactly how Earth went from a lifeless state to a with-life state, doesn’t mean the theory of evolution is just a guess. Anyone who argues is much, is denying all the work by the thousands of biologists who put in millions of hours studying this, often because they once read something in a competing religious text that disagrees with it. But reading one piece of anecdotal evidence doesn’t make someone an expert over those thousands of people putting in millions of hours of observations, testing, and studies. It takes supreme arrogance to think it does.

ABSOLUTE:

An absolute is something that is indisputable fact. For the most part, science would say you can never know an absolute, but that doesn’t mean they don’t exist. Quite the contrary. Technically, I’d argue everything is essentially an absolute—facts are all around us. Something either is or it isn’t.

But the problem for us unfortunately, is that you can’t know any of them absolutely, because you can never know what you don’t know.

On any subject, there may be something you’re unaware of that changes everything (like Einstein’s thoughts on gravitation waves which forced a rethink of Isaac Newton’s Universal Law of Gravitation), so you always have to remain open to new information.

Now that we’ve covered those, the reason it’s both wrong and insulting to say the theory of evolution is “just a theory” is due to the fact that thousands of scientists have done hundreds of thousands hours of work over the centuries on thousands of different aspects of evolution.

Work which is really hard to do, requires vast knowledge, is reviewed by their peers, and consistent with what they’ve all observed in the natural world repeatedly. All of it supports the theory of evolution, and is fundamentally different from creation which hasn’t been observed at all.

It should also be pointed out that DNA has largely confirmed evolution via mapping out genealogies of all living things. It’s also interesting to note that DNA wasn’t discovered until long after evolution was theorized. Much like when people thought the Earth was round, but then we went out to space and proved it is round by observing it.

So back to our “Evolution is JUST a theory” folks, most people who make this argument are people who are religious.

They’ve done no tests to confirm what their religion says is true, they’ve merely read a book that may or may not be true. They may accept it as faith, but this why it is called faith, not science.

While their belief might be right, demeaning thousands of brilliant minds who have done a lot of hard and painstaking work when they’ve done none, is profoundly insulting and ignorant when we see all the things around us that science has answered, and answered correctly.

This could be the curing of a myriad of diseases, being able to put a man on the moon, splitting an atom, or simply making a working smart phone. Science has a pretty amazing track record of being right.

Even if you are religious, let me ask you this. If you were feeling chest pains, and afraid you might be about to have a heart attack, are you calling 9/11 to summon a doctor first (a scientist), or would you call your priest and ask them to say a prayer first?

You can do both, but if the answer you chose is option one, you’re already instinctively putting your faith in science over religion, as I’d argue you should. So let’s stop putting religion over science in other aspects of our lives, too.