Over the past three years of writing for DI,  I have discussed evolution with many creationists who have posted comments at this site.  These exchanges have been good for me.  They have forced me to think harder about exactly what it is that I understand about evolution and what evidence supports my understanding.  These exchanges have also helped me to understand the concerns and mental gymnastics of creationists.

I now find myself getting increasingly impatient with the creationists, however.   It was initially interesting to banter with creationists because I enjoyed the challenge of trying to understand why they claimed the things they claimed.  I’m now getting annoyed with these creationists arguments, and it mostly has to do with the refusal of creationists to acknowledge relevant scientific observations from the real world.

My frustration also stems from the anti-scientific mindset of creationists.  As a group, creationists refuse to argue even-handedly.  They become skeptical only when it suits their immediate needs—they don’t apply skepticism equally both to their own claims and to the claims of those with whom they disagree.  As a group, they scurry to find disingenuous arguments to support points that they actually learned in churches, not in science books.  Many of them are consciously dishonest, and when you call attention to their obvious untruths, they try to change the subject.  There are exceptions to this rule.  There are some creationists who aren’t consciously being dishonest, but those creationists tend to be so incredibly ignorant of the principles of the scientific theory of evolution that they lack the ability to meaningfully criticize evolution.  Their arguments are aimed at things that no competent scientist has ever claimed.   For numerous excellent examples of this problem, see these videos by AronRa here and here.

It is well-established that humans are susceptible to committing errors caused by the confirmation bias.  We seek out evidence that supports our current beliefs.  Scientists are imminently aware of this danger and they work hard to design experiments to counteract this bias.  Creationists (who don’t even try to run experiments) excel at feeding their confirmation biases.  They proudly exclude evidence that threatens their opinions. Creationists come to mind when I consider David Hume’s quote:  “Reason is and ought only to be the slave of the passions, and can never pretend to any other office than to serve and obey them.” [A Treatise of Human Nature, (2nd Ed.), Book II, Part I, Section III (“Of the influencing motives of the will”) (1739)].

Creationists claim that the reason they don’t like the scientific theory of evolution is that the evidence presented by biologists is flimsy. I would admit that scientists can’t run scientific demonstrations of evolution as quickly or easily as we can run many physics or chemistry experiments. Many evolutionary biology experiments that could be run would take longer than the life span of those scientists who would run them (but see this long-term Russian experiment where foxes turned into doglike creatures over a 40-year period involving 35 generations).   The inability to run quick experiments does not disprove evolution in the least. In a book he wrote when he was 97 years old, What Evolution Is (2001),  renowned biologist Ernst Mayr admitted that evolution

is a historical process that cannot be proven by the same arguments and methods by which purely physical or functional phenomena can be documented. Evolution as a whole, and the explanation of particular evolutionary events, must be inferred from observations. Such inferences subsequently must be tested again and again against new observations, and the original inference is either falsified or considerably strengthened when confirmed by all of these tests. However, most inferences made by evolutionists have by now been tested successfully so often that they are accepted as certainties.

(Page 13).  When reading Mayr, it occurred to me that many people have a bias against circumstantial evidence, and evolution is (for the most part) demonstrable based on circumstantial evidence.  This bias against circumstantial evidence can also be seen in the legal field, where many jurors express concerns that circumstantial cases are per se deficient. Consider this example from Wikipedia, however:

If a witness testifies that the defendant was seen entering a house, then screaming was heard, then the defendant was seen leaving, carrying a bloody knife, that is circumstantial evidence; if a witness testifies that he/she actually saw the defendant stabbing the victim, that is direct evidence.

Ironically, many cases involving “direct” evidence (for instance, cases that depend heavily upon an eyewitness) can be flimsy (also consider that, in many cases, innocent people confess to crimes).  As Mayr admitted, we can’t stand around and watch most organisms evolve, because our life spans are not long enough. This logistical issue does not prevent good science from being done, however.  The bottom line is that A) evolution by natural selection is strongly proven by circumstantial evidence and B) there is nothing deficient about circumstantial evidence.

What are the overwhelming types of facts that support evolution by natural selection? I culled the following list of evidence from Chapter 2 of Mayr’s book, What Evolution Is.  Each of the following facts is well-explained by evolution but not by creationism.

I. The Fossil Record. Mayr contended that the fossil record is

“the most convincing evidence for the occurrence of evolution.” He points out the ubiquitous discovery of “extinct organisms in older geological strata.” In short, “no modern mammal… should be found in strata that are 100 or 200 million years old and indeed not has ever been found.”

Combine those observations with this: “The fossils found in the most recent strata are often very similar to still living species or, in some cases, even indistinguishable. The older the strata are in which a fossil is found-that is the further back in time-the more different the fossil will be from living representatives. (Page 13).  That there are gaps in the fossil record are understandable, given the “unimaginable incompleteness of the fossil record.” Nonetheless, Mayr pointed out that there are some remarkably complete fossil transitions in existence.  For instance consider the fossil record of whales (which originally lived on land) and horses.

II.  Homology. Homology refers to the “structural, physiological, molecular and behavioral characteristics of organisms.” Even prior to Darwin, comparative anatomists realized that many features were variants of the same underlying structure (consider the wings of birds and the arms of mammals). Darwin pointed out that two species were homologous “if they were derived by evolution from an equivalent characteristic in the nearest common ancestor of the two species.” Mayr points out that “homology cannot be proven; it is always inferred.”  On the other hand, it can be strongly inferred.  Homology in a particular case can be demonstrated through numerous criteria, including a; “the position in relation to neighboring structures or organs, B) by connecting two dissimilar features by intermediate stages in ancestors; see) by similarity and ontogeny; and D) by intermediate fossils.

III.  The branching structure of evolution and common descent. All organisms on earth appear to have common ancestors. Numerous studies using many kinds of evidence have now confirmed Darwin’s conjecture that

“There is grandeur in this view of life, with its several powers, having been originally breathed into a few forms or into one; and that from so simple a beginning endless forms most beautiful and most wonderful have been, and are being evolved.”

IV.  Morphological similarity. This refers to the study of comparative anatomy, which provides strong evidence of common descent. Organisms tend to be more related to the extent that they are similar morphologically.  “It is quite remarkable how successful comparative morphology can be in the reconstruction of missing steps in an evolutionary sequence.”  Additional evidence is provided by phylogeny, a special branch of biology that deals with the pattern and history of the descent of organisms.

V.  Embryology. Embryos of related animals are quite similar to each other. Human embryos, for instance, are not only similar to those of other mammals, but to embryos of reptiles, amphibians and fishes. Studying embryonic stages can show “how a common ancestral stage gradually diverged in different branches of the ancestral tree.  This leads to a far better understanding of the evolutionary pathways.”  Mayr points out a striking fact of ontogeny: “Why should the embryos of birds and mammals develop gill slits, like fish embryos? Gills slits are not a more general condition of the neck region of a terrestrial vertebrate.” (29)  Mayr admits, however, that embryology has sometimes been taken too far as a proof of evolution “‘Ontogeny is a recapitulation of phylogeny,’ I would say went too far, because at no stage of its development does a mammalian embryo look like an adult fish.”

VI. Recapitulation. This refers to the “appearance and subsequent loss of structures in ontogeny, which in related taxa are retained in the adults. Meyer points out that Baleen whales still develop teeth at certain embryonic stages (though these are reabsorbed). He characterizes this phenomena as “striking.”

VII.  Biogeography. Consider the geographic distribution of animals and plants on Earth.  Consider the pockets of contiguous similarity.  But why are the faunas of Europe and North America relatively similar, whereas those of Africa and South America are different?  Rather than rack this up as the product of creation, Darwin concluded that “the present distribution of animals and plants is due to the history of their dispersal from their original points of origin.”

VIII. Vestigial structures. Many organisms have structures “that are not fully functional or not functional at all.” (30). These are the remnants of structures that were functional in ancestors, but no longer.  On a related note, consider these incredible transitional fossils.

IX.  Molecular Evidence. As a general rule, “The more closely related two organisms are, the more similar are their respective molecules.” Such molecules also serve as a clock, allowing us further insight into the location of branching points.

This above list is formidable.  It demands a much better explanation than “God did it.” In fact, “God did it.” is not a scientific theory at all.
What is a “theory”?  I referred to Wikipedia for some well-considered formulations.  Consider this definition offered by the United States National Academy of Sciences:  “In science, the word “theory” refers to a comprehensive explanation of an important feature of nature supported by facts gathered over time. Theories also allow scientists to make predictions about as yet unobserved phenomena. . . . Such fact-supported theories are not “guesses” but reliable accounts of the real world.”

Stephen Hawking used a similar approach to define “theory”:

“A theory is a good theory if it satisfies two requirements: It must accurately describe a large class of observations on the basis of a model that contains only a few arbitrary elements, and it must make definite predictions about the results of future observations.”

Further, consider that the defining characteristic of a scientific theory is that it makes claims and predictions that are falsifiable or testable.  To be falsifiable, a theory must first be understandable.  In a famous comment on a paper someone showed him, Wolfgang Pauli captured the difference between scientific and unscientific thought by saying, “This isn’t right. It’s not even wrong.”

As used in science, a theory is not something you blurt out on a whim.   It is an overarching formulation to unify an entire field of study, including the facts, the laws, the inferences and the testable hypotheses.  Evolution unifies the entire field of biology.  As Theodosius Dobzhansky once wrote, “Nothing in Biology Makes Sense Except in the Light of Evolution.”   What does the “theory” of creationism offer to science?  Nothing at all.

Instead of offering a real theory to engage with careful scientific observations, creationists excel at turning their skepticism up and down like cheap thermostats.  Tellingly, when creationists consider chemistry, their skepticism-thermostats are set much like those of real scientists.   When it comes to the theory of evolution, however, creationists crank up their skepticism to such a degree that they no longer know anything about anything.  Back in their churches, however, they have no problem uncritically acknowledging the “fact” that Mary is a virgin or that the Earth is only 6,000 year old (to do the latter, they need to defy huge mounds of indisputable findings based on rigorously conducted radioactive dating).   Being a creationist apparently gives one the license to believe anything at all based on no evidence and to deny anything at all despite the existence of massive amounts of corroborating evidence.

Instead of dealing with the evidence by acknowledging it and testing it, Creationists offer us the following litany of beliefs (which I am paraphrasing from Eugenie Scott’s excellent book, Evolution vs Creationism (2004)):   What does creationism offer? There are two basic versions of creationism. First, consider the “biblical creation model,” which is based on the following three principles:

1. Creation was completed by supernatural process in six days.
2. Creation is in the bondage of decay because of sin and the curse.
3. Earth history is dominated by the great flood of Noah’s day.

The above items are so patently absurd that creationists don’t even try to force these teachings in public school science classes.  They would be laughed out of town even by most conservatives. The simplistic and provable absurdity of these claims is the reason biblical creation was given a facelift by the Discovery Institute. With its new facade, biblical creation has been converted into “scientific creationism,” and it offers this spruced-up advice:

1. The physical universe of space, time, matter and energy was created by a transcendent personal Creator who has always existed.
2. Biological life did not develop by natural processes from inanimate systems, but was specially and supernaturally created by the Creator.
3 Each major kind of plant and animal was created, completely formed, from the beginning. These organisms do not evolve from another kind of organism.
4 The first human beings did not evolve from other types of animals, but were specially created in fully human form by the Creator. Humans differ from other animals in that they have souls that allow them to be conscious, use language and honor their Creator.
5 People are able to have relationships with the Creator by exploring His creation rationally and scientifically.
6. Although nature largely works within fixed natural laws and uniform process rates, there is always the possibility of miraculous intervention in these laws and processes by the Creator.
7. The universe and life have somehow been impaired in character since creation, resulting in imperfections such as disease, aging and extinctions.
8. Humans can have purpose and meaning in their lives only because a Creator allowed for this.

(Page 139-140)

There is no evidence for any of these “scientific creationism” points.  Creationists fail explain any of the startling naturalistic phenomena described in the beginning of this post. These principles do not give any guidance for any research program. They don’t raise any questions that scientific experiments could possibly answer. They don’t allow scientists to generate any hypotheses that would invite scientific testing. They invite belief in subnatural beings and they encourage people to believe that natural laws can be turned off and on by a cartoonish Creator. They are the theological equivalent of saying “shit happens.”  How could you possible run scientific tests on “shit happens?”

I took the time to write this post because I wanted to see for myself how the scientific study of evolution compared with creationism side-by-side. Now that I can better see how the scientific program compares to the creationist “program”, it is clearer than ever that only one of these programs, the scientific version, actually engages with the natural world, giving us opportunities to explore and understand that world. The other “program” is merely an emotional salve. It is a dead-end program because it offers no hypotheses to test. It is not a “theory” because it does not even attempt to incorporate any facts, laws, inferences and testable hypotheses.  It is, at bottom, a way to prevent us from doing science.  Writing off the phenomena of the world as “magic” is not science.

[Image by Erich Vieth, utilizing the “Darwin Fish” image, which has been released into the public domain]