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A scientific theory is really a scientific fact

Creationists love to state that evolution is “just a theory.” And anti-vaccine activists love to say that the germ theory of disease is “just a theory.” The problem with those arguments is that each is a scientific theory, not a random guess.

All scientific theories are based on vast amounts of published scientific data, which is accepted by a wide range of scientists. A scientific theory is not based on the opinion of one random scientist.

And there’s one more thing — scientific theories are essentially scientific facts. Evolution is a scientific fact. Germ theory is a scientific fact. Human-caused climate change is a scientific fact. The safety and effectiveness of vaccines are scientific facts. I could go on, but I’ve got to limit the scope of this article.

two test tubes
Photo by Martin Lopez on

What is a scientific theory?

It’s hard to start this discussion without fully understanding what constitutes scientific theories. At the basic level, scientific theories describe the mechanisms (causality) of observed phenomena. The core component of a scientific theory is that it can provide explanations and predictions of similar phenomena that can be tested through the scientific method.

Scientific theories are not developed by one person writing a book in a library somewhere, they result from huge bodies of evidence developed over long periods of time. Theories rest upon the products of numerous contributors over time and are supported by vast amounts of evidence.

One person, even a Nobel Prize-winning biologist, cannot themselves “invent” a theory. Usually, a theory evolves (sorry, couldn’t resist) from initial research into hypotheses through scientific consensus to a published theory.

This process forms a continuum, and it may actually be impossible to point out the exact date the theory is embraced by the scientific community. The evolution of scientific theories is a key element of the scientific method as they are used to make predictions about the natural world.

This predictive ability is most certainly not something like a psychic, it is the ability to use the scientific method to question a prediction about a future result (say man evolving a fifth limb) and then answer it. If the theory of evolution predicts that fifth limb, but the prediction fails through a scientific study, then the theory gets revised.

The theory of evolution explains the fact of evolution because of the overwhelming evidence. But if someone were to bring something new, published in real science journals, we might revise the theory.

For example, there is a joke that evolution might be overturned if we found a rabbit fossil in a rock layer far earlier than when mammals evolved. But would that really refute evolution? Not really. Maybe it was an error in determining the age of the rocks, or our rock aging science needs revision. Or maybe, mammals evolved earlier than we thought. Or an alien visitor, intelligent rabbits, visited our planet 1 billion years ago. But finding a rabbit in some rock strata way below the point where rabbits evolved wouldn’t have an effect on the theory of evolution.

So this evolution theory is really a fact?

Not exactly, but close enough. Evolution is an observed fact. We’ve got over 200 years of observation of evolution in the form of fossils and in the form of living organisms. Few real scientists doubt the existence of evolution.

However, in the early 1800s, when science was just observing the change of species over time, there was no theoretical explanation of what we were observing. We didn’t know the mechanisms that were driving what we observed. That’s why some people proposed “some anonymous god did it,” a default position for those who cannot understand natural phenomena.

Then Charles Darwin and Alfred Russel Wallace independently described one of the foundations of evolution, natural selection.

But Darwin and Wallace didn’t know what we know today, so their initial “theory” has developed into a more complex theory of evolution that encompasses some of our newer knowledge, such as genetics and DNA.

Today, the theory of evolution, with some semantic changes depending on the author, states that evolution is a change in heritable traits of biological populations over successive generations as a result of natural selection or genetic drift. Despite the nearly 200 years since Darwin and Wallace were alive, the essential fact of evolution being a change in population over time has not been modified by new data. It has been strengthened.

That’s the great thing about scientific theories. They are built on huge mountains of evidence, not on guesswork or beliefs. They withstand the bright lights of criticism over time, but they are modified as new evidence is provided.

A scientific theory is powerful

Let me be clear. There is no question about the theories being constantly challenged, sometimes by real science, and sometimes by charlatans who just pull pseudoscience out of the thin air. Most theories are challenged, but those theories were rejected in favor of other theories.  Germ theory and evolution have not only withstood the test of time, they have withstood the test of newer and better evidence.

As scientists learned more about how biology works, in other words, as they gathered more data and evidence, our current theories, like germ theory and evolution (and frankly many more, like the Big Bang, climate change, and cell theory) became more solid, more predictive of future events. The science of vaccines is supported by germ theory (and evolution and cell theory), the most basic principles of the science of diseases and immunology. I guess one could reject vaccines for any number of silly reason, but the principles underlying vaccines is nearly unassailable.

Again, if you want to overturn germ theory, cell theory, evolution, or whatever, you just can’t say that it’s wrong, and expect any intelligent person to accept it without criticism. To refute these basic observed facts and underlying theories, you need mountains of evidence that debunks the scientific theory.

For example, there are over 1 million published, peer-reviewed articles supporting evolution. If you want to discredit the theory of evolution, then you need to bring a similar amount of research published by reputable scientists whose work stands up to criticism. That hasn’t happened for anything, not only for evolution, but for climate change, vaccine safety, and effectiveness, germ theory, or any other scientific theory.

What is the purpose of a scientific theory?

Because we need explanations, or we can’t further our research. We can observe, over and over again, that an apple falls down from a tree on this planet. The theory of gravity explains why. We find fossils in the ground that seem to show a link between humans and apes. However, the theory of evolution describes how apes and humans evolved from a common ancestor.

The theory of vaccination, yes it’s a scientific theory of immense power, is supported by germ theory, cell theory, and evolution. Good luck in refuting that science even though it may be possible (you see, real science is open-minded to all possibilities, including the possibility that we’re wrong, but only when evidence is presented), it is not probable.

Some random website is going to proclaim that Louis Pasteur was full of nonsense and that germ theory is a lie (probably pushed by Big Pharma and Monsanto), but that’s not evidence. That’s just a level of denialism that borders on the delusional.

The fact of evolution is supported by boatloads of evidence and if you don’t like it because it offends your beliefs, then just go hide under a rock.

Michael Simpson

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