The evolution/intelligent design debate has been rearing its ugly head once again in American courthouses. The issue is whether or not intelligent design should be taught side-by-side evolution in high school science classes.

To scientists (and others) this is a very strange debate. The question really boils down to whether or not creationism is as good of an explanation for the development of life as evolution is. There is no real dissention amongst the academic community on this issue: The answer is no, it isn't. But why not?

Intelligent design (I.D.) tells us things about the world; it tries to explain life's mysteries just like evolution does. Not only that, but in some cases I.D. claims to have answers evolution doesn't. Why is it then that I.D. has been sequestered to the political realm and most scientists aren't bothering to research the I.D. program?

I would like to try to provide a very brief explanation for this. If this is something that should go into our science programs, then there are criteria we can use to evaluate its claims to see if it really should make the academic cut. There are three major criteria that any statement must possess to be considered scientific: It must have explanatory power, plausibility and be falsifiable.

If we're talking science, we're talking about understanding some aspect of the universe we live in. We want science to explain how and why things work. Not just any explanation will do, however. We want something that will illuminate the process by which something is occurring. Bad scientific explanations do not tell us anything more than what we already knew. For example, explaining why my water bottle is empty by stating the obvious fact that the bottle has no water in it is a bad explanation. Giving a reason such as, “It got knocked over,” or, “My friend greedily drank all of it,” is much better because it provides a description of the forces behind the bottle being empty.

If a statement provides an explanation that might be suitable, it isn't in the clear yet. It still needs to be a plausible explanation. For an explanatory statement to be plausible, the forces or reasons provided cannot conflict with what we already know about the world. Saying aliens, ghosts or a dragon that lives in my closet is responsible for my empty bottle may provide reasons that could account for the empty bottle, but in light of what we know about the world this explanation isn't very plausible. The availability of one explanation does not replace or override the need for it to be plausible. Just because we can't come up with plausible reasons why something is happening does not mean we are obliged to accept anything handed to us. This would be like coming home to find your window broken, with no apparent reason for it except your neighbor telling you it was hit by an errant laser beam from an alien space battle. You can't see any other reason for it, but that doesn't mean you should believe your neighbor.

If a statement possesses those two criteria (explanatory power and plausibility) then it is ready to stand up to science's real test: endless attempts at proving the statement wrong by rigorously testing its accuracy from countless angles. This is why scientific hypotheses must be falsifiable. There must be some possible situation that is implied by the statement, that if found would falsify it. If there is no possibility of it being wrong under any conditions, then it cannot tell us anything about the world since anything we look at is accounted for by it and it is therefore not a falsifiable explanation. This is why it is so meaningful and important in science when a hypothesis stands up to the test of time and survives the efforts of scientists working worldwide trying to find just one real world instance that truly contradicts what the statement says. This is how (since philosophically nothing is provable anyway) we can be sure of what we think we know about the world. It is by this process of never leaving any hypothesis alone that scientists refine our understanding of how the universe works.

It is on these three important criteria that intelligent design in its current vestige fails to be taken as science. I.D. provides us with claims about how the world is, but many of its claims are not plausible or falsifiable. The idea that there are structures which are irreducible in their complexity and were therefore designed intelligently is an example of swapping availability with plausibility. It fails the requirement of being falsifiable by claiming that organisms were designed to only appear as though they have evolved. Now it doesn't matter how life arose or how compelling alternative evidence is, I.D. can explain away any other accounts.

Before Darwin's theory of evolution, intelligent design was a serious endeavor even though it was providing no answers about how life works or why organisms seem to be really good at living in their environments but are far from being perfectly fit to operating in them. Evolution has provided us with a very good explanation for this, and intelligent design is suffering the same fate phrenology did after the development of modern psychology. It was a field that provided explanations that weren't testable, and with the advancement of other fields that did a better job of explaining the same problems, was ultimately dropped. This is why I.D. isn't a serious topic in science and why it should not be taught alongside evolution in science classes. It would be like requiring Aristotelian physics to be taught alongside Newtonian mechanics.