What Makes Evolution a Theory?

What is a theory? Does the observation of gravitational force involve the same concepts as gravitational theory? The misconceptions surrounding the term “theory” stem from differences in how the term is defined. In this intriguing short film, Dr. Jeff Hardin discusses key ideas relating to the definition of scientific theory and what this term means in the context of evolutionary biology.

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Dr. Jeff Hardin is chair of the department of zoology at the University of Wisconsin. He is the senior author of World of the Cell (Pearson Education, 2015).


Dr. Jeff Hardin: Theory, for the average non-scientist, means something very different than what it means for a scientist. What we mean in modern parlance would be I’ve got a hunch, I’ve got a guess. Something like that. Don’t really have facts to support my idea, but I’ve got a hunch about that. That is not what scientists mean when they use the word theory.

Let’s think about gravity. I think we’d all agree that gravity exists. If I raise an object and then I drop it, that object’s going to fall. Why? Because through repeated observations we’ve shown that gravitational attraction is a fact. Now, gravitational theory is something different, right? Isaac Newton had a theory about how gravity works. Albert Einstein has a theory about how gravity works that encompasses Newton’s ideas. It’s a bigger one. The explanation for how gravity works, that’s a theory. It’s a very broadly encompassing set of inferences that explains the facts, and not only that, it makes new predictions that can be tested.

When people use the phrase ‘evolutionary theory,’ that’s what they mean. They’re not disputing that evolution has occurred. In fact, the evidence that evolution has occurred is overwhelming. The theory of evolution has to do with how does that evolutionary change occur over time? What are the mechanisms that explain evolutionary theory? That’s where Darwin proposed a theory of evolution by natural selection. Now, that’s been augmented with our understanding of genetics, so genetics comes into play, something Darwin didn’t really know about. So, when we use the word theory, it doesn’t mean a hunch, something we wish were true, something like that. No, it’s something so compelling that it is the dominant paradigm by which we understand lots of biological phenomena.


  • Course Categories: Biblical Studies, General Theology
  • Science Topics: Earth Science & Environment, History & Philosophy of Science, Life Sciences
  • Tags:
    science and religion, what makes evolution a theory, evolutionary biology, evolutionary theory, natural selection, Dr. Jeff Hardin

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