On Teaching Evolution in U.S. Public Schools

Consider the following statement:

    All life on Earth was produced by impersonal forces, without any overriding design or purpose.

Is this statement "true," and should it be taught as fact to public school students?

Core Questions

In my opinion, the so-called evolution/creationism "debate" revolves around this statement (or something similar) and these two questions.  That is, the question is not whether or not organisms evolve, whether or not creationism should be considered scientific, or any of the other host of issues that are generally associated with the evolution/creation conflict.  The question is whether or not public school science students should be taught that the only reasonable belief is that God played no significant role in the creation of life.

On one side of the debate, many religious parents feel that "godless science" is trying to teach their children that there is no God, or at best that God may exist but is irrelevant.  Their concerns about the teaching of evolution are largely derivatives of this primary concern.  On the other side, science is by definition dedicated to finding natural explanations for observations, explanations that have no reference to supernatural phenomena.  Most scientists are therefore understandably opposed to any attempt to bring supernatural explanations of the origins of life into the science classroom.

Is there a middle ground that can satisfy, or at least mollify, both groups?  I believe that there is.  In a nutshell, I believe that the key is to teach students the current scientific consensus and to also teach them about the limits of the scientific method to determine "truth."

Scientific Consensus

It would seem to be stating the obvious to say that when scientists have reached a consensus on some topic of research, this consensus should be taught concerning that topic in public school science classrooms.  However, when it comes to teaching biological evolution, on which there is tremendous scientific consensus, look out!  Some creationists have gone so far as to essentially claim that the teaching of evolution in U.S. public schools is the result of a conspiracy among atheistic scientists who know that evolution is bad science but are nonetheless determined to undermine the faith of religious students through the teaching of evolutionary theories.  Therefore, the reasoning goes, even though there appears to be a consensus, it is not a scientific consensus.  This justifies teaching "true"--creationist--science alongside "pseudo-scientific" evolutionary theories.

Notice that this line of reasoning hinges on the belief that (some) scientists are trying to use science to attack the religious convictions of students, stirring a visceral response in many parents.  Thus, to the extent that science education circumscribes any supposed attempt at attacking students' convictions, the response of these parents may be significantly blunted, and many of their objections to teaching the scientific consensus could be expected to dissipate.  But can science education perform such a role, and should it?

Science Has Limits

Let's return to the statement above.  The first phrase--all life on Earth was produced by impersonal forces--is tautological from a scientific perspective.  That is, scientific inquiry begins with the premise that all natural phenomena have natural explanations.  In particular, since life is a natural phenomenon, the scientific assumption is that life has a natural explanation.  This might seem to be an attack on certain religious beliefs, but it is not.  It is simply an assumption made for the purpose of seeing how far naturalistic explanations can be carried and for comparing various naturalistic explanations with one another.

In particular, notice that evolution, or any other scientific theory, can never "prove" that life was produced by impersonal forces, since the scientific process begins by assuming this and no theoretical process can prove its own assumptions (assuming that no assumptions are redundant, which we can assume in this case).  In fact, science cannot rule out the possibility of supernatural intervention in any process even if the process is explained by what is considered a well-established theory (a "law").  The framework of science ignores the possibility of supernatural events, so if such an event was to occur it would be viewed scientifically as a problem for the theory, spurious data, etc., but not as a supernatural event.  However, assuming for the sake of scientific study that such possibilities do not exist is not a proof that such possibilities do not exist, no matter how well theory fits observations.  Again, there is simply no valid way to prove the assumptions of a theoretical framework within that framework.

Another limitation of the scientific process is that it can never arrive at the conclusion that "there is no possible theory" for some set of observations.  The most negative conclusion it can produce is that "none of our current theories is fully satisfactory" in accounting for the observations.  But there is always the possibility that someone will develop a clever new theory that is more satisfactory.

So, is it "true" that all life on Earth was produced by impersonal forces?  Well, if you believe (philosophically, and not just for purposes of scientific inquiry) that every natural observation has a natural explanation, the answer is "yes, of course!!"  I suppose that one could even claim that "science" believes that this claim is true.  But it cannot be claimed (honestly) that science has "proved" this statement in the normal sense of the term "proof."  The most that might be said along these lines is that science has produced a theory--biological evolution based on random mutation plus natural selection--that seems to generally fit well with observation and that provides the best naturalistic explanation currently for life's development from single-celled organisms to present forms.  That is, the theory of biological evolution has been "proved" in the scientific sense of being the best current naturalistic explanation.  However, science is incapable of proving more generally that biological evolution is the correct ("true") explanation, or even that it is the most rational explanation.

This latter point is subtle but crucially important.  Science has been so successful in so many areas of inquiry that it is tempting to believe that the scientific method is the only rational method for producing explanations.  After all, since it has worked so well in the past in so many areas, how could we rationally believe that it will not work well in all areas of inquiry and do so forever more?  Put in such strong terms, you may see the problem: how can we possibly know that the scientific method will always work well?  Obviously, we can't prove that it will.  We have a tendency as humans to believe that past observations are indicative of future behaviors, but we have no proof that this will be the case.  All we have is our belief, which is not necessarily rational.

Let me put the problem another way.  The scientific method is based on the inductive method: from specific observations we induce a general explanation that agrees (at least most of the time) with the observations.  And why do we think that the scientific method is a good way to produce explanations?  Because we have observed that it seems to have worked well in the past.  That is, our belief that it is good is based on inductive reasoning!  In other words, based on inductive reasoning, we believe that inductive reasoning is a good way to produce explanations.  This is, of course, a circular argument, and therefore not valid (deductive) reasoning.  In short, we have no proof even that science produces the most rational explanations of observations, let alone that it produces the correct explanations.  (For a fuller treatment of this line of thinking, which originated with the Scottish philosopher David Hume several centuries ago, I suggest the book "The Foundations of Scientific Inference",  by Wesley C. Salmon).

Now let's turn to the second phrase of the original statement, dealing with purpose and design.  It seems to me that many who believe philosophically that every natural phenomenon has a natural explanation also believe that there is no ultimate purpose or design for the universe.  But notice that these are two separate beliefs.  One could, for example, rationally believe that impersonal laws govern this universe, but also believe that these laws were designed for some purpose by a personal intelligence.  In fact, I would go so far as to say that science itself is mute on the topic of origins of the laws that it presumes exist.  While there have been some philosophical hypotheses about apparently naturalistic ways in which our universe's laws could have arisen, these musings are not science per se since they do not offer testable hypotheses.  Besides, any attempt to produce naturalistic (law-based) explanations for the origin of the laws of our universe simply begs the question of the origins of the supposed meta-laws.  Ultimately, the questions of origins of natural laws are philosophic and not scientific.  This implies that no one origins philosophy can claim to be more scientific than any other.

What Students Should Be Taught

It would seem, then, that there are two key points on which both sides in the evolution/creation conflict can and should agree:
  1. The public school science classroom is not the place to teach various beliefs about supernatural phenomena in general, and beliefs about possible supernatural interventions in the origins of life in particular.  These topics are outside the scientific fields of inquiry.
  2. The public school science classroom is also not the place to disparage beliefs about supernatural phenomena, for exactly the same reason: these topics are outside the scientific fields of inquiry!  To ensure that students are not confused about the role of science in arriving at beliefs, it is vital that students be taught explicitly and implicitly in science classrooms that:
I suppose that one could argue that what I advocate teaching in the second point is some of the philosophy of science, not science itself, and so does not belong in the science curriculum.  But this would be a disingenuous argument: to teach science without examining its assumptions is essentially to teach science as if it makes no untrue assumptions, that is, to teach that supernatural phenomena either do not exist or can always be safely ignored.  In other words, teaching science in this way is essentially teaching not only the scientific method but also teaching a certain philosophical viewpoint.  Again, I believe that it is the implicit teaching of this viewpoint that is at the heart of much of the rancor creationists express concerning the current approach to teaching evolution.

Making My Point

I believe that a careful treatment in the classroom of the underlying philosophical assumptions made in the pursuit of science as a discipline would go a long way toward relieving the concerns of many religious parents of public school students.  On the other hand, defenses against creationist "attacks" on evolution, such as Scientific American editor-in-chief John Rennie's " 15 Answers to Creationist Nonsense" (July 2002), seem more likely to continue the nonsense1 than to end it.  If evolution was carefully presented in science classrooms as what it is and no more--the scientific community's current best attempt at producing a naturalistic explanation for life as we know it, with all of the limitations outlined above--then it would seem that much of the pressure to "attack" evolution (or, more to the point, attempt to defend a theistic philosophy of origins) would be relieved.  

Let me focus for a moment on Rennie's essay, since it prompted me to write this piece.  Some of his arguments, viewed through the philosophy-of-science lens I have described above, just serve to make my point about science education.  Take his opening sentence, for example: "When Charles Darwin introduced the theory of evolution through natural selection 143 years ago, the scientists of the day argued over it fiercely, but the massing evidence from paleontology, genetics, zoology, molecular biology and other fields gradually established evolution's truth beyond reasonable doubt."  I assume that Mr. Rennie is here implying the adjective "scientific" before the words "truth" and "doubt."  That is, I assume that he agrees that a "scientific truth" is never necessarily correct, and that it is therefore always reasonable to doubt a scientific truth, even if it has been established beyond doubt from a scientific perspective by showing truly remarkable agreement with observations, being simpler than alternative theories, etc.  Are these meanings of "truth" and "doubt" clear to the typical reader of Scientific American?  I suspect not, precisely because I suspect that very few non-scientists are ever taught to distinguish between scientific truth and unqualified truth.  So I strongly suspect that the typical reader sees this sentence as saying that "evolution is true beyond reasonable doubt, period."  But this statement is simply not true, by the reasoning above, and I for one think that public school science curricula need to make this clear so that the general public has a better understanding of claims such as Rennie's.  As it is, such a statement seems only likely to further incite creationists.

For the specific case of evolution, as opposed to the discussion about science in general given above, here's another way of seeing the absurdity of a blanket "true beyond reasonable doubt" claim.  Rennie himself notes that some "antievolution" authors have identified certain "evolutionary problems as unsolved and difficult (which no one disputes)."  How can it be unreasonable to doubt a theory such as evolution that has difficult unsolved problems?  Isn't it possible that these problems will never be solved by evolutionary arguments, that the theory (or some significant portion of it) will prove to be wrong? Well, if evolution is essentially the only reasonable naturalistic theory explaining certain observations and if a naturalistic theory must exist, then there is no reasonable alternative.  But if we drop the naturalistic assumption that such a theory must exist, then there are many reasonable (although non-scientific) alternative explanations, and it becomes not only reasonable but perhaps sensible to entertain doubts about evolution.  In terms of teaching evolution in the classroom, while it would probably be inappropriate to present possible non-scientific explanations, it would seem eminently appropriate to present various problems--that no one disputes--with evolutionary theory and to point out that it is reasonable to have doubts about at least some of evolution's claims.  After all, one of our goals in science education should be to teach students that our scientific understanding of the world is--for lack of a better word--constantly evolving, and that a prime way in which we improve scientific knowledge is by identifying shortcomings in current theories and working either to modify or supplant the theories.  So introducing science students to shortcomings in current evolutionary theory would seem to be an excellent way to show these students that science doesn't already have all the answers, that there is still work to do, that maybe some of our theories--yes, even evolutionary theories--are just plain wrong.  What better way to calm creationists than to candidly admit that their core belief that God played a significant role in the creation of life on Earth may turn out to be correct, that no one can prove (without assumptions) that they are wrong?

Some Humility

To summarize, it seems to me that both sides in the creation/evolution conflict could use a little more humility (OK, so could we all, but that's another story ;-).  Creationists need to recognize that supernatural explanations are not scientific explanations and to back off from any attempts at forcing public school science teachers to present non-scientific explanations in the guise of science.  Evolutionists need to recognize that scientific explanations are not necessarily equivalent to unqualified truth and to back off from any attempts to use public school teachers to present scientific "truth" and the scientific method as more than they are, in the process belittling nonscientific but still feasible beliefs.


Footnotes

1. For the record, I don't believe that all of the creationist work alluded to in Rennie's article qualifies as "nonsense," nor that he would even necessarily make such a claim.  On the other hand, I do agree with Rennie that there is a great deal of creationist nonsense and certainly concur with his desire to see an end to the promulgation of that nonsense.


Copyright © 2002 Jeffrey Jackson.  All rights reserved.