I. Charles Darwin’s theory of evolution, called natural selection, stated that different species originated from shared ancestors, with the differences in the organisms being caused by adaptations to different environments. The environment determines which species are best fit to survive, and the traits of the organisms are passed down to new generations. With enough time, such passages of traits could lead to whole new species. This theory was developed after more than two decades of observations, studying thousands of animal and plant samples, all with extraordinary inferences drawn from observed similarities and differences.

II. Intelligent Design (ID) is essentially a negative argument: the forces at work, whether natural selection or something else, are not sufficient to bring about aspects of life which we observe, such as humans—therefore, there must have been an intelligent designer. The appearances of organisms, then, have nothing to do with the survival success of their ancestors, like in natural selection: the intelligent designer brought life about quickly in all the various forms we observe today, as opposed to the slow process theorized in natural selection.

III. Using the evidence I’ve seen for both proposals, I’ve concluded that evolutionary theory better explains the phenomena of different life-forms. I’ll establish why I think so by considering the simplicity, explanatory power, and predictive success of both ideas.

IV. In terms of simplicity, I think that evolutionary theory wins hands down. Speaking about ontological complexity, both ideas incorporate the existence of various life-forms, but with Intelligent Design one must also include the existence of the designer, as well as the tools used in the design. In addition, a problem is raised regarding the origin of the existence of the intelligent designer; since it has abilities far more complex than even the current abilities of human beings, are we to suppose that it too was designed? In respect to dynamic complexity, both theories appear to accept the reproductive capabilities of organisms (I’m not sure about Intelligent Design), but Intelligent Design is the more complex nonetheless. Natural selection would imply the existence of biological processes which explain the similarities between offspring and parent organisms; such a thing isn’t too hard to believe because we can observe reproduction in organisms, meaning that something must be functioning within them which allows for such a thing. But Intelligent Design posits the existence of design processes outside of what goes on in reproduction, which have to be more complex because such designing gives rise to not just one type of organism, like a calf, but a multitude of organisms.

V. Evolutionary theory also wins in regards to its explanatory power. Through the fossil records, the gaps between species are bridged; fossils indicate a transitional stage from one type of organism to another, just as Darwin believed would be the case. Intelligent Design cannot account for such transitional fossils, and every fossil found sheds greater light on the bridges between species and the weakness of ID’s hypothesis.

VI. ID’s argument of irreducible complexity, which argues against evolution, fails to explain life forms because certain organisms have parts which are similar to other organism’s parts, but serve different purposes which lend support to evolution. A great example of this was the bacterial flagellum, which ID posits as an organism with an irreducibly complex motor; its motor has a similar structure to a syringe-like part belonging to the Yersinia pestis bacterium, and this is because they are made of the same kind of protein, but the Yersinia simply lacks the number of proteins need for the motor. Despite missing such proteins, the structure functions as an apparatus for carrying diseases, particularly the Bubonic plague; this is hard evidence that this motor then is not “irreducibly complex.”

VII. Lastly, I think evolution sort of wins by default in regard to predictive success, even though its success is astoundingly positive. ID offers no predictions. After its initial claims regarding the designing of species, it is silent regarding the implications of such designs, if any—meaning that there is nothing for scientists to test. Whereas evolution offers a plethora of predictions, with no scientific discoveries ever found which contradict such predictions in over 150 years. Darwin’s prediction about the fossil record was proven true, and modern genetics has recently proven Darwin’s contention of a common ancestry of humans and apes. In fact, every observation and experiment made, whether in molecular biology or modern genetics, has only confirmed the truth of evolution’s theory. This shows evolution to be an argument with a high degree of predictive success.

VIII. The conclusion then is that whether one looks at simplicity, explanatory power, or predictive success, it is clear that Darwin’s theory of evolution by natural selection trumps the idea of Intelligent Design, and demonstrates a coherent and testable prediction regarding the origin of species.

Notes and References

Some of the material for this essay is from the PBS video “Judgment Day: Intelligent Design on Trial.”