Natural Selection Semantics: A Student Reacts to a Young-Earth Definition of Evolution

One method of examining a student’s grasp of a complex topic is to confront that student with an alternative point of view and ask them to critique it. If that student has a good working knowledge of the subject, they should be able to recognize the broad philosophical underpinnings of that alternative viewpoint and be able to identify misconceptions and poor or deceptive arguments.  I frequently challenge my undergraduate students with articles, short videos or quotes from sources such as product advertisements, popular magazine articles, and new stories about science, and have them critique them in small groups before having a class discussion. More recently I decided to extend this challenge to a my current PhD student in the context of his comprehensive exams.

Comprehensive exams (also known affectionately as “comps,” “prelims” or “quals”) as a large step in the process of becoming a doctoral candidate in our program.   They can take on many forms but our committee chose to use a fairly traditional format. Each of the five members of my student’s dissertation committee were afforded a whole day in which the student is asked to provide written answers to questions spanning the range of expertise represented by the committee member and which they believe relevant to the students training.  After many months of preparation my student spent 8 hours a day for a whole week composing answers to questions given to him each morning. Following these written exams he will move on to an oral examination. If he passes both he will officially be recognized as a PhD candidate and can pursue his doctoral research which will hopefully conclude with the writing and defense of a dissertation, usually within 2 to 3 years.

The last day of questions was reserved for my own questions. I had requested my student write two essays in eight hours.  The second involved responding to a large body of literature which I provided him with in the months leading up to the exam by applying it to his own research interests.  He is generally interested in science communication/education with a focus on using games for communicating science to the public in formal and informal settings.  More broadly, he is pursuing a career at a natural history museum.  He should have been expecting the second challenge but the first question was more of a surprise and was meant to test how well he could construct a cogent essay under time pressure, using what he has learned about science communication, and apply it to a real-world challenge to conventional biological theory.

I mention how the comprehensive exam was administered so you will understand that the essay that I am going share with you was written under some significant duress.  By the time my student was writing his essays for me he had already written more than 30 single spaced pages of text for other members of the committee.  Because my second challenge was a bit more daunting he could not afford to devote any more than half of his total time to the construction of this essay.

The challenge: Respond to a video produced by young-earth creationists about  the relationship of natural selection to biological evolution.

Here is the most relevant portion of my directions which I provided to him the morning of his exam:

I want you to write a response of no more than 2000 words to a video featuring Answers in Genesis’ “creation scientist” Dr. Georgia Purdom entitled: Is Natural Section the Same Thing as Evolution? Think of the task as writing a long letter to the editor for the New York Times.  You should critique the science but you should remember your audience are not scientists.

The entire video of Dr. Purdom’s can be found at the top of this Answers in Genesis webpage:  Below is a transcript in which I produced of the most important parts of that video.

“Is natural selection the same things as evolution?  Well, the short answer to that is no.  But let’s take a more in-depth look at why that’s the case.  The first thing we need to do is define natural selection and evolution.  Natural selection is an observable process in which organisms with certain characteristics survive better in a given environment, and there is a loss of information in the DNA. Genetic information decreases as a result of this process.  Evolution is defined as an unobservable process which has occurred over long periods of time in which a single-celled organism has become all the organisms that we have today and have had in the past.  It is directional in the sense that dinosaurs have evolved into birds and genetic information must increase in order for this process to occur. So, as you can see from the definitions they are very, very different.”

After a short discussion of the development of antibiotic resistance in bacteria, Purdom continues:

“So what have we really observed here?  First of all, bacteria remain bacteria. It is non-directional and genetic information has been lost as a result of this process. So, even if you give natural selection long periods of time, such as millions of years, it simply can’t do what evolution requires of it which is move in a certain direction and to add genetic information.  There is no doubt natural selection has resulted in changes within kinds of animals.” 

How would you respond? Is Dr. Purdom accurately portraying evolutionary theory? Where does she make valid observations?  A critique doesn’t just point out fault but can show where there is correct thinking but possibly mixed with error.  As much as possible try to use examples that show where she may be mistaken or isn’t telling the whole story.

After your essay you should reflect upon your on your own essay and write a short discussion about how what you have learned from the literature about effective science communication helped inform your approach to writing this article.

So, without further ado, I present, with his permission, this student’s response in its entirety.


Dear Reader,

This letter is a response to the video titled Natural Selection found at  This site shows Dr. Purdom answering the question:  Is natural selection the same thing as evolution?

Screenshot of the Answers in Genesis webpage with Dr. Purdom's video. Below is the title of the first article below the video. Page:
Screenshot of the Answers in Genesis webpage with Dr. Purdom’s video. Below is a YouTube version of the same video. Page:

This video presents an argument, even if it seems more like a series of questions and answers in response to a simple prompt. Countless similar videos and articles both on the Answers in Genesis website and others, present this same argument, one based upon the claim that evolutionary theory is unfounded. Successful communication between individuals necessitates shared understanding of the facts at hand, and so in any debate, it must be established that both sides are arguing with the same language, the same meaning. However, in this video, we can see use of what can only be described as using semantic (relating to the meaning of language) smoke and mirrors, combine with a willful reinterpretation and/or ignorance of evidence in preference to religious dogma.

Dr. Purdom begins her video by stating that the short answer to the question, of whether natural selection is the same as evolution, is no. She begins with providing definitions of the two scientific terms in the source question. Her definition of natural selection is mostly correct. However, she ends it with, “and there is a loss of information in the DNA. Genetic information decreases as a result of this process.” But what does information mean? If we’re talking about DNA, the suggested meaning here is that genes, or chromosomes, or sections of DNA, are being destroyed. And if this were to occur, then yes, it would be a loss of information. But this is not what occurs in Natural selection. Some of the variation in versions of genes (sets of DNA) may be lost as organisms which are less fit (in biology, fitness refers to organisms’ ability to reproduce in relation to one another; more fit organisms are more likely to survive to reproductive age and produce more offspring), but the total amount of “genetic information” in any given organism is not changing due from natural selection alone (more on this later).

She goes on, “Evolution is defined as an unobservable process which has occurred over long periods of time in which a single-celled organism has become all the organisms that we have today and have had in the past.” However, yet again, if we examine actual definitions (drawing here from the simple English Wikipedia article to make its meaning very clear) Evolution is “a scientific theory used by biologists. It explains how living things change over a long time, and how they have come to be the way they are.” The theory of evolution makes no implicit statements about the results of evolution (eg. single-celled organism has become all the organisms), but rather the processes which explain them; nor is it implicitly unobservable, the science behind the theory of evolution is, like all science must be, based on observations.

Dr. Purdom then states “So, as you can see from the definitions, they are very very different.” This is the capstone of this article’s semantic smoke and mirrors, the source of the visceral disagreement between biologists and skeptics: she provides definitions, different from those used by her opponents, and then uses her definitions for arguments about the nature of natural selection and evolution as they relate to one another. So, before we even come close to the later portion of the video where she brings up dogmatic conflicts, she is making an argument against evolution using definitions that are not the same as those used by evolutionary biologists. In this way the foundation of the science involved is being intentionally weakened by dissenting from using shared meaning as her opponents. She then considers the initial question satisfactorily answered, and leaves it behind to use her particular definitions in her continuing arguments.

Dr. Purdom then uses the occurrence(s) of antibiotic resistance in bacterial populations as an example of natural selection complete with a loss of “information.” She describes antibiotic resistance as occurring, due to mutations, with an intrinsic “cost,” “Genetic information has been lost as a result of this process.” In many real instances, this cost is not the loss of genetic information, as she would have you believe, but rather the metabolic (energy) cost of producing the factors involved in the resistance. In addition, there is also the process of biased mutations, wherein there is no intrinsic difference in cost between two versions of a gene (such as one involved in resistance), and so whichever version is most common will naturally occur more frequently in a population. This is why in normal bacterial population (one free of antibiotics) you see mostly sensitive bacteria; they are either spending less energy than those that are antibiotic resistant or simply occur in smaller numbers until selective pressures are applied (antibiotics are introduced).

This is compounded by her insistence that such antibiotic resistance occurs directly and solely through mutation, again, carrying with it her definition of mutations coming at a “cost,” which she implies to again be this “loss of information.” Mutation is the source of novel genetic variation as genes are reproduced with a small chance of errors in copy sequence. Genes can also move between populations through gene migration. As an example, we can imagine one rancher’s herd of cattle meeting another, and some members of each group breeding, passing their genes along to the offspring in another herd (this can be called vertical gene transfer, from parent to offspring). In bacterial systems, where they do not have genetic recombination through sexual reproduction, we do see the transfer of genes laterally (from one individual to another, as opposed to vertical gene transfer) from bacteria to one another; thus, a bacteria which has antibiotic resistance can provide a copy of the relevant genes to other bacteria, not losing its own, and adding, not replacing genes in the other bacteria. Mutations as well can lead to duplications, additions to, and changes in genes; mutation can generate new “genetic information.” Purdom’s assertions that natural selection cannot produce more complexity is correct, but it neglects the important role of naturally occurring mutations in populations producing new variability.

It is worth noting here, that the short and long answer to her prompt, “Is natural selection the same thing as evolution?” is still no. Natural selection is one of many processes that together produce the patterns of change and development underlying evolutionary theory.

“The pattern of evolution is descent with modification from common ancestors. The principle mechanism that drive this change is natural selection.” (Freeman & Herron, 2004).

A recurring motif throughout both this and other media concerning evolution skepticism is again this idea of semantic smoke and mirrors. Arguments frequently involve the circular logic that the public often considers natural selection and evolution to be the same, and thus determining that natural selection is not, entirely in and of itself, evolution, somehow disarms the theory of evolution of its validity. Evolution is not in and of itself a force, a singular process, it is the description we use for the cumulative result of a number of different processes, including natural selection, mutation, gene migration, and genetic drift. Purdom and others like her are altering their interpretation of words to allow them to dismiss them based off of these misinterpretations.

By using smoke and mirrors to test the concept of evolution by different parameters than they are described to do, it is only natural that the theory of evolution would seem to be on shaky ground.

The remainder of the video then takes her personal framing of the nature of evolutionary theory and natural selection as a possible process contributing to it (she believes it does in fact not) and conjoins it to the dogma of the Young Earth Creationist movement. The Young Earth Creationist movement’s model of the Earth’s history, simply, is that the universe was created between 5,700 and 10,000 years ago, over the course of six 24 hour days, based off of the doctrine of biblical inerrancy, a literal interpretation of the bible.

It is here that one can recognize a functional purpose of the way Purdom has reinterpreted and spun her definitions to help bolster a specifically contrary dogmatic belief system using altered forms of scientific concepts. Scientists labor to understand the systems, mechanisms, and processes by which the world around us operates; they have no agenda for or against religious belief systems. However, when our observation- and evidence-based understanding of the universe produces conflict with religious writings and beliefs, we cannot defer to dogma. It is the preference of persons such as Dr. Purdom that scientists be perceived to be trying to disprove religious ideas and destroy faith, when in fact they are pursuing knowledge of the world with no theistic or atheistic biases. The arguments that Purdom are founded on a presumption of biblical inerrancy, which plays no role in the nature of science. Her assertions not only misframe the definitions of words in the contexts of their use, but reframes the arguments themselves to be those with which scientific exploration has no desire to participate in.

PhD Student
University of xxxxx
Integrated Biosciences Program


I have included here the web address for the Simple English Wikipedia entry for “Evolution” as a useful starting reference for anyone interested in understanding the ideas which actually underlie evolutionary theory. The Simple English version of wikipedia avoids overly technical language, and by extension, much of the semantic fog and mirrors that can be used to misrepresent complex concepts.

I have also included a link to a free PDF of the last of Darwin’s revised editions “On the Origin of Species”. Reading even just a few of the introductory chapters will rapidly illustrate the observations Darwin utilized to support the notion that natural selection can result in changes in populations, contributing to the larger idea of evolutionary theory. The book can be readily found for free online, as it is within the public domain, and can also be acquired relatively cheaply anywhere books are sold.

Part 1 Reflections

As stated by Fischhoff (2013), “The goal of science communication is not agreement, but fewer, better disagreements.” While this statement has a particularly broad application to all forms of science communication, it becomes especially pertinent when addressing the arguments of skeptics, whether they be of evolutionary theory or global climate change. Climate change and evolution skeptics rely frequently on what I have referred to throughout my letter as “semantic smoke and mirrors” or, to put a less pejorative tone to it, semantic fog. In either case, obscuring or denying consensus on the topics at hand allow them leeway to entrench their ideas in seeming facts (I hate to feel a need to use the term “alternative facts,” but when the shoe fits…). Both within these camps and the general public there is a growing distrust, or at least growing lack of reliance, on expert opinion, in preference to whatever rhetoric is seen most often, or most loudly. Where scientific communication may have been at one point confined to the realm of mere education, it now is more and more frequently faced with the hurdles of, to be hyperbolic, deprogramming misconceptions first before new information can be learned.

It has been shown that education, particularly education outside of formal class environs, is mostly effective at building upon and reinforcing pre-existing knowledge and understanding of topics (Rennie & Williams, 2004), while the construction of new knowledge and mental models is far more difficult. This is particularly so when learners are aware, or made aware, of realms of knowledge that will produce cognitive dissonance with their mental models (Mckeachie et al, 2002; Wiles & Alters, 2011), and especially when they can decide to avoid such dissonance (Glaze & Goldston, 2015). This can make scientific communication difficult, as generating cognitive dissonance is one of the more effective ways to address misunderstandings (Bybee et al, 2006). This all results in the compounding of psychological, educational, and sociocultural factors which all make redressing changes in thought and understanding far more complex than merely presenting facts or data to support the truth of an idea.

All of the above elaborates the principles that underlay the rationale for the mental models approach to developing communication (de Bruin & Bostrom, 2017). To me, the challenge of modern science communication is to enable recognition of the value and use of cognitive dissonance as a means to improve learning. This is why the importance of “semantic stasis” (to borrow a term from evolution that almost assuredly is already used in linguistics, considering their phylogenetic similarities) is the major point of focus in my letter. I not only highlight the disconnect between Purdom’s definitions and the actual, but further elaborate why these differences both improve the perceived strength of her argument, and are the fatal flaws at use. In many ways, an important factor for science literacy is the ability to recognize the misuse of scientific language to communicate alternative facts. It will never suffice to explain merely why such sources are wrong without explaining why the sources are providing incorrect information to begin with. Just as the didactic content of any informal material will not be intrinsically interpreted correctly unless it’s expected outcomes are explicitly defined (Afonso & Gilbert, 2005), the accuracy of “facts” will not be questioned unless the motives and intent of science “miscommunicators” is laid bare.


  • Afonso, A. S., & Gilbert, J. K. (2003). Educational value of different types of exhibits in an interactive science and technology center. Science Education, 91(6), 967–987.
  • Bruine de Bruin, W., & Bostrom, A. (2013). Assessing what to address in science communication. Proceedings of the National Academy of Sciences, 110(Supplement_3), 14062–14068.
  • Bybee, R. W., Taylor, J. A., Gardner, A., Van, P., Powell, J. C., Westbrook, A., … Knapp, N. (2006). The BSCS 5E Instructional Model : Origins and Effectiveness. A Report prepared for the Office of Science
  • Fischhoff B.  2013. The sciences of science communication. Proceedings of the National Academy of Sciences of the United States of America. 2013;110 (Suppl 3):14033-14039. doi:10.1073/pnas.1213273110.
  • Freeman, S., Herron, J., & Jon, C. (2004). Evolutionary analysis. Retrieved from
  • Glaze, A. L., & Goldston, M. J. (2015). U.S. Science Teaching and Learning of Evolution: A Critical Review of the Literature 2000-2014. Science Education, 99(3), 500–518.
  • Mckeachie, W. J., Lin, Y.-G., & Strayer, J. (2002). Ceationist vs . Evolutionary Beliefs: Effects on Learning Biology. The American Biology Teacher, 64(3), 189–192.
  • Miller, J. D. (1998). The measurement of civic scientific literacy. Public Understanding of Science, 7(3), 203–223.
  • Stoltzfus, A., & Yampolsky, L. Y. (2009). Climbing Mount Probable: Mutation as a Cause of Nonrandomness in Evolution. Journal of Heredity, 100(5), 637–647.
  • Weber, J. R., & Schell Word, C. (2001). The Communication Process as Evaluative Context: What Do Nonscientists Hear When Scientists Speak? BioScience, 51(6), 487–495.
  • Wiles, J. R., & Alters, B. (2011). Effects of an Educational Experience Incorporating an Inventory of Factors Potentially Influencing Student Acceptance of Biological Evolution. International Journal of Science Education, 33(18), 2559–2585.
  • Yampolsky, L. Y., & Stoltzfus, A. (2001). Bias in the introduction of variation as an orienting factor in evolution. EVOLUTION & DEVELOPMENT, 3(2),

End of student response


My response to this essay and its significance

You might be thinking, “hey, this is your student so he probably had a lot of familiarity with young-earth creationism and so would have been prepared for this question.”  In other words, didn’t I just throw him a softball question?

The reality is that my student had little knowledge of the views of young earth creationism—especially with respect to how they define speciation and natural selection—other than the general characterization that creationists don’t believe in evolution.  We had attended an Answers in Genesis talk “Jurassic Prank” last fall and had talked about YECs a few times in the preceding months but he would not have known Dr. Purdom’s views or writings.

However, I knew he was very interested in exploring and testing how to overcome common misconceptions people have with many important scientific theories.  As part of his dissertation research, he has been involved in designing and implementing new labs in classes in my home department to test ideas that are inspired by what he has learned from his reading of the science education literature.

I would expect anyone who is interested in science education who is going to be confronted with explaining the basic mechanisms of evolution to be able to deftly analyze a video such as this one by Purdom.  You still might still think this was an easy challenge, but I know from experience that it is not. I have given a very similar challenge to my undergraduate bio-majors students.  None of those students were able to provide the depth of analysis that this doctoral student was able to. Many identified some of the most blatant errors that Dr. Purdom makes including the redefining of terms and application of motive to evolutionary outcomes. But beyond identifying errors they may have recently been exposed to in class, many of their responses demonstrated that they had their own misconceptions about how natural selection works.

Would I agree with everything that my student has written? Not completely, but it is quite good given the time constraints.  I’ve written my own response to Purdom in the past in which I raise my own concerns, many of which align well with what my student has independently written.

I compare my undergraduate students’ responses to this PhD student’s response to make the point that it can take many years of experience for students to confidently and accurately identify factual and semantic errors in descriptions of evolutionary processes and to be able to turn a critical eye not just toward anti-evolutionary claims but even toward the evolutionary biology literature.

I also bring this essay to you to illustrate the point that becoming an “expert” in this field requires many years of study and personal experience with data collection and analysis. This is something that Dr. Purdom lacks having obtained her PhD in a different biological subdiscipline.

Dr. Purdom represents the general approach of Young-Earth Creationists to explain biological diversity

In recent years, Answers in Genesis has increasingly turned its attention to providing “explanations” for the patterns of biological diversity we observe alive today and in the fossil record. In other words, they have been putting more effort into seeking alternative hypotheses to current evolutionary theory which encompasses a suite of processes—including natural selection—by which different kinds of living organisms are thought to have developed and diversified from earlier forms during the history of the earth.

As they move into the arena of explaining biological diversity, AiG has sought to embrace (See my archive of articles on YEC’s embrace of rapid-speciation) some evolutionary terminology while maintaining their distance from the word “evolution” itself.  Dr. Purdoms video is a prime example of this maneuver.  

Dr. Purdom is not a trained evolutionary biologist, nor can I find evidence that she has ever taken any evolutionary biology course.  She graduated from a college that had an anti-evolution curriculum and obtained her Ph.D. from a graduate program at The Ohio State University that would not have required any evolutionary biology training nor provided any further knowledge of evolutionary biology to complete her degree.  So, it is not surprising that her grasp of evolutionary theory could be rather limited, especially if, like many YECs, she reflexively shies away from any mention of evolution in her reading.

Unfortunately, Dr. Purdom is treated as an authority figure or “expert” in the eyes of her target audience.  This is what is particularly troublesome to me about her presentation.  She and many other YECs use the same incorrect definitions to instill a false sense in their audience that scientists have failed to properly consider these issues and are instead dogmatically holding to a “theory in crisis.”  I see the same misguided language on FaceBook every day and I hear the same kinds of comments from lay Christians at seminars and conferences that I attend. Christians who rely on AiG for expert advice feel that they are fully justified in their criticisms of evolutionary theory because they believe that “experts” like Dr. Purdom are providing them with competent analysis and answers when they are, in fact, misleading them with obfuscation and false definitions.

I don’t fault non-biologists struggling to understand species concepts, genetic diversity and natural selection for latching onto ideas that fit their preconceived notions of evolution.  But public figures like Dr. Purdom have a much greater responsibility for providing accurate statements and fair analyses because they are in a position of influence. Regardless of how well supported—or not supported—you think evolutionary theory may be, I would hope that we all expect that those that speak as authority figures would have a good understanding of what they are teaching.  Unfortunately followers of AiG in these matters have been let down by their authority figures.


The republishing of this comprehensive exam response was done with full permission of the student who has reviewed and helped to edit this article.  Only very minor edits for typos and the addition of the video link were made to the students essay.

Editing provided by TB and LC

22 thoughts on “Natural Selection Semantics: A Student Reacts to a Young-Earth Definition of Evolution

  1. This is an excellent article, but I would say that the prospective doctoral student swerved into one of the same mistakes that Dr. Puram made, specifically that of “… providing defininitions different from those used by [one’s] opponents”, with his statement,

    “The Young Earth Creationist movement’s model of the Earth’s history, simply, is that the universe was created between 5,700 and 10,000 years ago, over the course of six 24 hour days, based off of the doctrine of biblical inerrancy, a literal interpretation of the bible.”

    The doctrine of biblical inerrancy is independent of a literal interpretation of the bible. There are many who hold to the doctrine of biblical inerrancy who do not subscribe to the YEC interpretative model and their notion of “a literal interpretation of the bible” (e.g. our friends at Reasons to Believe,

    Liked by 2 people

    1. I think that this is an excellent article and analysis too. I have a similar response as Tom Milligan regarding this comment:

      Evolution is “a scientific theory used by biologists. It explains how living things change over a long time, and how they have come to be the way they are.” The theory of evolution makes no implicit statements about the results of evolution (eg. single-celled organism has become all the organisms)…

      I disagree and I believe that evolution is understood by those who study and support it to mean that “how things have come to be the way that they are” absolutely leads to the “results of evolution.” I cannot recall reading any article by a supporter of evolutionary theory that did not imply that not only does evolution address how an organism has become what it is, but also explains how all organisms have come to be.

      Again, I believe it to be an excellent article, but since the point of the article has to do with semantics around the meaning of evolution and its disparate processes, one should also be careful to do the same. To say that evolution does not address abiogenesis is one thing, but to suggest that common understanding of the scope of the theory does not imply that evolution is directly responsible for the speciation of the planet is another thing.

      Do you agree Joel? MC

      Liked by 1 person

      1. I agree. Its the same type of problem that TM pointed out in the comment above. You have hit on something that I’ve noticed in the creation/evolution debate. I do hear that evolution has nothing to do with the origin of life as if that topic were somehow completely separate. This is just a method to avoid a more difficult discussion.

        Liked by 2 people

      2. To further this idea, we often hear an evolutionary biologist say that “evolution simply means ‘change over time’”. Of course, no one can disagree with that. Subsequently however, the definition evolution itself subtly and silently “evolves” in the discussion to mean neo-Darwininsm and all that encompasses and expands outward to the origin of life through “chemical evolution”.

        On the YEC side, evolution has come to encompass all of reality. For example, in the YEC mind, Astrophysicists, etc. are “evolutionists” regardless of their views on neo-Darwinism, this because they hold to the notion of star and planet formation over a course of a long time via gravitationally assisted accretion of material in gas clouds.

        That is to say that I have noticed that there is something of a shell game that occurs in discussions of “evolution” for which one must be on-guard, and this occurs on both sides of the fence.

        Liked by 1 person

        1. If evolution simply means ‘change over time’ then even a melting ice cube is evolving. The YEC side (some at least) does recognise that organisms can adapt and produce new species within the created Kind.


      3. I’m not really in a position to critique this particular student’s paper, but I have also noticed that both anti-evolution creationists and those who acknowledge evolution as an accurate understanding of the origin of species tend to conflate “evolution” and “evolutionary theory.”

        In biology, “evolution” is the change in population allele frequencies over generations. Put another way, the observed traits in a population change from one generation to the next. This is readily accepted even by the most ardent anti-evolution creationists. Of course, they play semantic games with this as well, trying to redefine it as “microevolution” or “adaptation” (both terms with a scientific definition and both used incorrectly by those attempting to redefine “evolution”).

        “Evolutionary theory,” on the other hand, is a wide-ranging set of explanations of processes which affect and effect (I don’t get to use those words together very often!) the changes that are observed from one generation to the next. Just as “music” is a collection of sounds over time, “music theory” describes the relationships of those sounds to each other and to time. “Evolution” is descriptive, while “evolutionary theory” is explanatory and predictive.

        This is why I never refer to “the theory of evolution” when engaging in such discussions. There is currently one prevailing theory of evolution (“Neo-Darwinian Evolution”/”Modern Evolutionary Synthesis”), but that does not mean there could not be more. This is an important distinction that, I think, gets far too little attention even from those who understand the difference.

        Liked by 2 people

        1. Thanks for the clarification. It was very well said. I guess the point that I was trying to make is that this conflation of the two terms has become so universal that it is now understood that evolution / evolutionary theory refers to the changes in traits within a population, that sometimes result in a new species. CRR also makes this point below. This is why the discussion is even happening. The article was in response to a statement on the meaning of the terms. Since there are laypersons, like me, involved, the historical meanings tend to give way to the popular meanings. When anyone, on any side, suggests that evolution (or the theory) refers only to changes within a species, most of us bristle in response, because this is clearly not the entire scope of what is being suggested. Look at “marriage” for instance. There is a historical definition and a popular one. Any discussion of the subject is folly unless careful consideration is given and all parties agree upon the terms used.


  2. I guess that the most important points here (and they were made clearly in the post by your student) is that any debate or discussion must first begin with a clear definition of the topics at hand, as well as the scope over which they (the debated topics) have effect.


    1. Sorry, Joel… I meant to say “points here… are” not “points here… is”… Mike


  3. I fell sure the student passed, but I have a question that will indicate my age.

    Did the student write this out by longhand, or type it on a screen? The fact he provided bibliography would suggest the testing process was not cut off from resources, so he should have been able to use a computer, but Academics (at least in the humanities fields I’m familiar with) can be very conservative.


    1. He had access to a computer for writing his answers out though not all his exams allowed that and he did write one long-hand. Its up to each person asking questions what restrictions they will impose.


  4. We can’t be too critical since the student was asked to write this with significant pressure and time constraint; and perhaps knowing the expectations of his examiner.

    Purdom’s definition of [the theory of] evolution is perhaps poorly expressed but is consistent with that used by some evolutionists; e.g. Jerry Coyne in “Why Evolution is True” where he goes back to “perhaps a self replicating molecule”. These origin events are certainly in the unobservable past.

    PhD Student says “The theory of evolution makes no implicit statements about the results of evolution (eg. single-celled organism has become all the organisms), …”. This is incorrect both today (Coyne, above) and in “Origin of Species” where Darwin says “Thus, from the war of nature, from famine and death, the most exalted object which we are capable of conceiving, namely, the production of the higher animals, directly follows. There is grandeur in this view of life, with its several powers, having been originally breathed by the Creator into a few forms or into one; and that, whilst this planet has gone cycling on according to the fixed law of gravity, from so simple a beginning endless forms most beautiful and most wonderful have been, and are being evolved.” Rather than no implicit statements about the direction of evolution this is quite explicit.

    Liked by 2 people

    1. I agree and don’t intend to be critical at all… but rather to make the point that you are making. That any discussion of the topic wherein the definition does not include the creation or development of all species is lacking for the purpose of the conversation.

      Liked by 1 person

    2. I am not sure I understand how the statement “from so simple a beginning endless forms most beautiful and most wonderful have been and are being evolved.” contradicts the statement that “evolution makes no implicit statements about the results of evolution”.
      The first quote seems to be an observation, the second a description of theory. The first quote’s observation of a permutation of the theory does not imply an alteration of the theory (in the same way that if I throw a baseball up and away from Earth, that does not imply that the equations for acceleration due to gravity are wrong).


      1. Hi Tom: I agree with what you say about it contradicting. Good point. What I was hoping to say (and I don’t believe I made the point well) is that in an article about the definition of evolution, especially one that juxtaposes one view of it vs. another, the author needs to be careful to not create a mistaken perception. To me, any supporter of Darwinian evolution (whatever flavor) in fact believes (despite the textbook definition) that the effects of evolution have resulted in all of the disparate species of plants and animals. So, to “observe” all of the forms that “have been and are being evolved” and also point out that “evolution makes no implicit statements about the results” are incompatible in this venue. It may be that the definition is as described here, I don’t know, but I don’t believe that any serious adherent to the theory thinks that evolution isn’t the cause. We may say that Santa left the presents for our kids, but we mean that we left them. Evolution’s definition may not make implicit statements about its own results, but the results are definitely implicit in the general understanding of the term. Do you agree? If you throw a ball up into the air, and it comes down, everyone understands that it was gravity, not a hidden rubber string, that brought it back to the earth.


        1. thehonestskepticatgmaildotcom:
          Thank you for the reply. I agree that supporters of evolution attribute all the disparate species as being some of the theory’s possible results. But I think I am missing your point about the significance of “the results are definitely implicit in the general understanding”.

          Based on evolution, if single celled organisms had been more successful at resource acquisition and reproduction than multicellular organisms, then multicellular organisms would be out competed and a rarity if they exsisted at all. Exclusively unicellular organisms is another possible outcome but also not implicit in the theory. That beautiful and diverse multicellular organisms exist is only evidence that multicellularity was an effective survival strategy.

          The only general understanding, that I am aware of, that implies a result is the ladder concept of evolution producing sequentially “higher” organisms. Is that what you meant by the results being implicit in the general understanding? While the “ladder” interpretation of evolution is mostly thought of as incorrect, I am having trouble thinking of another interpretation which has implicit results predicated on something other than individuals’ ability to pass advantageous traits on to viable offspring.

          And yes, I agree completely with your extension of the ball analogy (which I interpret as meaning that no agent outside the theory is needed to understand the results).


          1. Hi Tom: Thanks very much for your reply and explanations. I guess that this statement (“evolution makes no implicit statements about the results of evolution”) is just really confusing. To me, evolution is a description of a process, including the results, and, in context with the article, it seemed that it was out of place. It read as though it was saying that there was a disconnect between evolution (a process) and speciation (a result.) Your clarification that what it means is that evolution does not expect SPECIFIC results, such as what are observed, is very helpful. I still believe that the statement is fuzzy because evolution is nothing apart from the results. Maybe it should say that evolution makes no specific statements (predictions?) about the results of evolution? Anyhow, to me it caused confusion and the reason that I brought it up was because the article was written to address confusion over the terms.

            Regarding the ball analogy, yes, that’s very close what I meant. :) What I meant was that you are understanding that the cause (gravity) brings the ball back to earth (the result), but you do not contemplate any other means (like a rubber band.) Your understanding of the cause and effect are limited to that single consideration (gravity.) Similarly, adherents to evolutionary theory have a general (universal) understanding that everything that is alive is due to the results of evolution. So it is not just the understanding of the theory or its results, but it is actually limiting the possible causes from the beginning.

            The ladder concept example really helps. The sequentially higher organisms are observed, but not implicit in the theory. The process could have gone any direction, but only ended up going the way that it went.

            Thanks again for your response and explanations.



            1. Mike,
              I have enjoyed our exchange. Thank you for your willingness to converse and I agree that statements frequently get fuzzy as you note. Mix in some interchangeable terms whose definitions vary depending on educational background of the user and I am surprised mutually clear communications occur as often as they do.

              Since you liked the ladder reference I thought I would convey the example that helped my understanding.
              1) swim bladders of fish, which are less complex but develop from the same embryonic tissue as air sacks and lungs,
              2) the air sack of lung fish, which are more complex than swim bladders, and less complex than lungs, but develop from the same embryonic tissue as lungs and swim bladders, and
              3) vertebrate lungs which are the most complex of these three organs which share embryonic origin
              When asked to arrange these 3 organs in terms of their sequence of evolution the novice biology student (including me) typically answers with the “ladder of complexity” answer and says swim bladders appeared first, then evolved into air sacks which then evolved into lungs. While the “ladder of complexity” answer is common, it is also inaccurate. The correct answer is that air sacks in lung fish appeared first and then evolved into both the less complex swim bladders of some fish and the more complex lungs of vertebrates.

              I have always liked that example. And if I have provided you no new information then I thank you for tolerating my indulgence!


              Liked by 2 people

              1. Thanks Tom! I too have enjoyed the dialog and your explanations. Each response generates a litany of questions, but I think that Joel’s blog is probably not the venue. I do appreciate your time and patience. Thank you again! MIke


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