Does Evolution Meet the Criteria for Scientific Theory

Evolution Meets the Criteria for Scientific Theories

Creationists complain that evolution isn't valid or genuine science, but exactly the opposite is the case: evolution meets the criteria accepted by scientists as defining science, and the vast majority of scientists accept evolution as science. Evolution is the central organizing framework for the biological sciences and is just as scientifically valid as analogous theories in other scientific fields: plate tectonics, atomic theory, quantum mechanics, etc. Creationist complaints rely upon misrepresentations of both evolution and science, so understanding what makes something scientific is helpful here.

Criteria for a Scientific Theory

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To fully understand how and why evolution is scientific, it's important to first know what the generally accepted criteria for scientific theories are. Scientific theories must be:

  • Consistent (internally & externally)
  • Parsimonious (sparing in proposed entities or explanations)
  • Useful (describes & explains observed phenomena)
  • Empirically Testable & Falsifiable
  • Based upon Controlled, Repeated Experiments
  • Correctable & Dynamic (changes are made as new data is discovered)
  • Progressive (achieves all that previous theories have & more)
  • Tentative (admits that it might not be correct rather than asserting certainty)

Evolution is Consistent

Although there are gaps in our knowledge, disagreements as to how evolution occurred, and gaps in the evidence, the idea of common descent is still overwhelmingly supported by both historical and contemporary evidence as well as our understanding of how changes occur in living organisms. All evidence we have supports evolutionary theory and common descent; absolutely no evidence points to anything else. Evolution is also externally consistent: it does not contradict solid findings in any other physical science. If evolution did contradict physics or chemistry, that would be a significant problem.

Evolution is Parsimonious

Evolution is naturalistic and does not add unnecessary concepts, entities, or processes to our understanding of the universe. Evolution, which is just genetic change over time, does not rely upon any entities or concepts which do not otherwise exist in any scientific model. Common descent does not require us to imagine anything new or unusual in the universe. This means is the theory of evolution is the simplest and most reliable explanation of the diversity of life on our planet. Everything offered as alternatives requires us to imagine new entities not used or needed in any other scientific model, like gods.

Evolution is Useful

Evolution is the unifying principle of the life sciences, which includes medicine. This means that much of what is done in the biological and medical sciences could not occur without the background premise of evolution. I've yet to see any Evolution Deniers willing to give up modern medicine. Evolutionary theory also suggests lots of problems for scientists to work on because it makes predictions which, in turn, provide experiments to perform in order to better understand what's going on in the natural world. Evolution thus provides an overall paradigm for solving current problems within the life sciences.

Evolutionary Theory Can Be Tested

Because evolution as common descent is largely a historical science, testing it is complicated — but it's not impossible. As with other historical investigations, we can make predictions and retrodictions (utilize present information to infer or explain past events or states) based on the theory. We can thus state that we would expect to find certain things (like types of fossils) when looking at the historical record; if they are found, it supports the theory. We cannot perform the direct tests like those often found physics and chemistry, but the theory of evolution is as testable as other historical theories.

Evolutionary Theory Can Be Falsified

Falsification of evolution as common descent would be complicated because of the vast amount of supporting evidence. Evolution rests upon a general and widespread pattern of evidence from many different fields, so a similar pattern of contradictory evidence is needed to falsify it. Isolated anomalies might force modifications, but no more. If we found a general pattern of fossils in rocks dated to different ages than expected, that would be a problem for evolution. If our understanding of physics and chemistry changed significantly, causing us to find that the earth is quite young, that would falsify evolution.

Evolutionary Theory is Correctable & Dynamic

Evolution is based solely on the evidence, thus if the evidence changes so will the theory; in fact, subtle changes to aspects of evolutionary theory can be observed by anyone who regularly reads biology journals and pays attention to the scientific debates. Evolutionary theory today is not quite the same as the evolutionary theory which Charles Darwin originally devised and wrote about, though he was correct enough that much of what he discovered continues to b valid. Since there are gaps in our understanding and evidence, we can expect to see more changes in the future as our understanding expands.

Evolutionary Theory is Progressive

The idea that a scientific theory should be progressive means that a new scientific theory should build on earlier scientific theories. In other words, a new theory must explain what previous theories explained at least as well as they did while providing a new understanding for additional material — something which evolution does. Another way to see how scientific theories need to be progressive is that they can be shown to be superior to competing theories. It should be possible to compare several explanations for a phenomenon and find that one does a much better job than the others. This is true of evolution.

Evolution and the Scientific Method

The general theory of evolution easily meets the criteria for scientific theories. How about the scientific method: was the idea of common descent arrived at scientifically? Yes — the idea was arrived at by examining nature. Looking at existing species, examining their characteristics and commonalities, and considering how they arose led to the idea of common descent. We can see the scientific method at work at every stage of the study of evolution and the biological sciences; in contrast, we find not the scientific method but theology and religious orthodoxy behind evolution’s creationist competitors.