Wednesday, April 29, 2009

More on Teleology in Evolutionary Biology

I’ve been corresponding via email with a fellow evolutionary biologist (who shall remain nameless). I thought that some of her/his comments might be useful or interesting to those who read this blog, as they have a direct bearing on the "problem" of purpose (i.e. teleology) in evolutionary biology.

My correspondent's comments and questions are in block quotes:
I’ve been following the ‘Survival of the Sickest’ thread at Uncommon Descent, and have some comments on it and on your essay on the (un)reality of adaptations.

First, a major area of agreement between us is that the original post is fatally flawed by:

1) the assumption that “Darwinism” implies “constant progress”, and

2) failure to understand that fitness is always defined relative to a particular environment, and that environments change over time.

Now, on to some points of disagreement:

You mentioned Gould and Vrba’s 1982 paper on exaptation, and wrote:

"The reason is quite simple: if (as Gould, Lewontin, and Vrba argue) adaptation isn’t legitimately part of what evolutionary theory is about, then the whole idea of “design” and “function” is read completely out of evolution, leaving only descent with modification."

I have been very strongly influenced on this topic by Warren Allman, director of the Paleontological Research Institute here in Ithaca. He asserted that all adaptations should be considered to be exaptations. His rationale for this assertion was that the term “adaptation” has built into it an assumption of teleology. Literally translated, the word "adaptation" means “toward usefulness”. It’s the “toward” part that is the problem. As you and I both understand it, evolution (including natural selection, but not artificial selection) does not tend toward anything. It has no goal as far as we can tell. Ergo, it builds on what has gone before, but without any specific goal “in mind”.

This is why “exaptation” expresses better how we understand natural selection. It builds “away from” non-functionality (or even away from previous functionality), but never really “toward” anything at all as far as we can tell. And, if Sewall Wright’s “shifting balance” theory is a reasonable model of evolution, then it never really “arrives” anywhere at all, since the “goal” is constantly shifting anyway.
I’m wondering why you think that Gould and Vrba regard adaptation as being outside the legitimate scope of evolutionary theory. My take on the paper is not that they regard the concept of adaptation as illegitimate, but just that it has been typically construed too broadly and should be broken down into the categories of true ‘adaptation’ and ‘exaptation’, where they define a true adaptation thusly:

“Following Williams, we may designate as an adaptation any feature that promotes fitness and was built by selection for its current role.”

The problem I have with this definition is the inclusion of the words “promotes” and “for”. “Promotion” means exactly what it says: “motion towards” something. Ergo, using this word immediately suggests teleology, and as I have pointed out above, teleology cannot be a valid assumption in the origin of the products of evolution at any level. This is not because including teleology allows for “a divine foot in the door” (c.f. Lewontin, 1997), but rather because it requires that the “plan” for the teleological process must exist prior to the coming into being of that process. When we do things, this assumption is perfectly valid, but when something happens in nature, such an assumption is entirely unwarranted. Where, in nature, could such a pre-existing plan exist?

As for the word “for, I always point out to my students that teleological explanations virtually always reduce to sentences that include the phrase “in order to”. This can be shortened even further to “to” (leaving out the “in order”). However, the entire phrase “in order to” can be replaced with the word “for” without changing its meaning. Ergo, the definition quoted above is still irreducibly teleological, and therefore includes an assumption that we should not make in evolutionary biology.

In my paper on the evolution of the capacity for religious experience, I began with a succinct definition of “adaptation”, from which I lay out four criteria that a characteristic (i.e. a “trait”) must meet to be considered a genuine adaptation.

An evolutionary adaptation is any heritable phenotypic character whose frequency of appearance in a population is the result of increased reproductive success relative to alternative versions of that heritable phenotypic character.

Here are the four criteria that I believe must be met for a characteristic to be considered to be an adaptation:

1) An evolutionary adaptation will be expressed by most of the members of a given population, in a pattern that approximates a normal distribution;

2) An evolutionary adaptation can be correlated with underlying anatomical and physiological structures, which constitute the efficient (or proximate) cause of the evolution of the adaptation;

3) An evolutionary adaptation can be correlated with a pre-existing evolutionary environment of adaptation (EEA), the circumstances of which can then be correlated with differential survival and reproduction; and

4) An evolutionary adaptation can be correlated with the presence and expression of an underlying gene or gene complex, which directly or indirectly causes and influences the expression of the phenotypic trait that constitutes the adaptation.

I would now modify criterion #4 to state that such genes/gene complexes must be shown to have been conserved, relative to other sequences in the genome. However, one must keep in mind that such conservation, while necessary, is not sufficient. As we know now, some sequences are conserved, but can be knocked out, with no discernible effect on phenotype. Ergo, to fully satisfy criterion #4, a characteristic must be shown to be associated with a particular gene or gene complex, the knocking out of which can be shown to have significant negative effects on fitness.

Obviously, this means that a great many characteristics that we observe in living organisms will not qualify as adaptations. I believe that this is fully justified, following Williams’ assertion that the concept of adaptation is “onerous” and should only be resorted to “in the last resort”. It is only by doing so that we may avoid the otherwise almost inevitable pitfall of appealing to teleology in our explanations.
Gould and Vrba close their paper with this:

“The argument is not anti-selectionist, and we view this paper as a contribution to Darwinism, not as a skirmish in a nihilistic vendetta. The main theme is, after all, cooptability for fitness. Exaptations are vital components of any organism’s success.”

There’s that nasty little word “for” again! Fitness is immediately measurable as relative differential reproductive success, but “adaptation” can only be legitimately inferred retrospectively. We can’t say that something is a genuine adaptation until it already is, and this seems to me the kind of logical circularity that has also plagued Herbert Spencer’s phrase “survival of the fittest”. If we stick to the four criteria listed above, we will rarely fall into the trap that teleological thinking always sets for us.

Also, you later wrote the following, which seems to acknowledge that Gould and Vrba did regard adapation as a legitimate part of evolutionary theory:

“Yes, indeed, except that I believe that Gould, Lewontin (and later, Vrba) were, like Darwin, unwilling to take their principles to their logical conclusion: that adaptations (like species) are a figment of the human imagination, and do not actually exist in nature (or, to be even more precise, do not have to exist in nature).”

What I meant by this is that the only way we can actually “detect” the presence of adaptation is by inferring it. In that sense, adaptations are not “primary” characteristics; that is, characteristics that can be directly observed (such as differential reproductive success). Rather, such “secondary” characteristics must be indirectly inferred. In that sense, they are indeed “imaginary”; we must “imagine” that they exist (as the result of our application of inferential logic), as we cannot observe them directly.
Am I missing something? Are you trying to say that although Gould and Vrba regarded adaptations as real, they nevertheless thought they should be excluded from evolutionary theory?

No, I’m saying what Williams was saying, only I’m saying it more strongly and consistently: that we should never include any hint of teleology in our explanations, as such inclusion includes the biological equivalent of that old bugaboo of physics: “action at a distance” in physics is the equivalent of “goals preceding causes” in biology.

When I reread Williams’ famous 1966 book, Adaptation and Natural Selection, which supposedly reads teleology out of evolutionary biology, I was astonished to find it shot through with the same kind of teleological reasoning that he was supposedly trying to eliminate. I think I could find all the “hidden teleology” in Williams because I have spent so much time debating with ID supporters. They are the ultimate teleologists, and can always find where we have subtly woven teleological assumptions into our biology.
Finally, you wrote:

“To be as clear as I can, I believe that asserting a position of “metaphysical materialism” is just that: a metaphysical, not a scientific assertion. Confusing metaphysics with science is nearly as pernicious as confusing “ought” and “is”. The former makes for questionable science and the latter makes for questionable ethics.”

I would agree that science has no say on metaphysical questions that don’t have observable consequences (although I would argue that even then, Ockham’s razor should cause us to prefer simpler metaphysical systems to needlessly complex ones). However, some metaphysical assertions do have observable consequences. For example, I consider the existence of the Young Earth Creationists' God to be a metaphysical assertion that has nevertheless been decisively falsified by science.

I agree, but the same cannot be said for the more subtle versions of teleology found in Michael Behe or William Dembski's works. Their books (especially Dembski’s) present a much more subtle and less easily refuted version of teleological explanation, one that is easily reinforced by our own unwitting resort to teleological explanations.

Evolutionary adaptation is where the rubber of both evolutionary theory and ID hit the road.
Now on to your essay “Are Adaptations ‘Real’?”

You wrote:

“...although there are characteristics of organisms that are correlated with relatively high reproductive success (and would therefore be considered by most evolutionary biologists to qualify as “adaptations”), it becomes problematic to decide exactly which of those characteristics are the “real” adaptations and which are merely ‘accidental’”.

The problem, of course, is the words “real” and “accidental”. If we are genuinely dedicated to rooting out teleology in all of our explanations of the origins of biological objects and processes, then all adaptations are “accidental”, in the sense that they are all unplanned. We perceive them as having “functions” because our naive viewpoint of reality is always teleological. We can think non-teleologically only with very great difficulty. It’s like special relativity or quantum mechanics. We have to twist our minds to be able to even begin to conceive of them, and even then we constantly slide back into our naive (and unwarranted) views of reality.

True, if by “accidental” adaptations you mean exaptations. But while it may sometimes be difficult to tell whether an adaptation is “real” or “accidental”, that is not evidence that “real” adaptations don’t exist. Indeed, the only scenario I can envision in which “real” adaptations would not exist would be one in which every fitness-enhancing feature was an exaptation.

But that would mean, among other things, that every incremental improvement to the eye would have to have been the accidental result of changes that were selected for some reason other than improved vision. That seems far-fetched to me. Am I misunderstanding your position?

It’s not that that every incremental improvement to the eye would have to have been the accidental result of something, it’s that every incremental change to the eye would have had to originate accidentally, but then increase in frequency as the result of differential survival and reproduction. If we think the way you worded it (and we almost always think that way), then the teleological trap is that all of the incremental changes are somehow “predestined” and that complex eyes must be the inevitable result.

But this just plays into the hands of intelligent Design supporters. When we argue that “half an eye is still adaptive” we unwittingly include the assumption that “half an eye” is just that: half of what will ultimately evolve by natural selection. But our knowledge of the natural history of vision has shown us over and over again that “half an eye” is the whole thing in many cases. We can only say that the eyes of, say, flatworms, are “half an eye” because we already know that such a thing as a “whole eye” exists in cephalopods and vertebrates. We have to disabuse ourselves of the idea that any characteristic is only partially the whole deal. All characteristics of all organisms are the whole deal for those organisms, period, end of story, that’s all She wrote. Anything else contains the beginnings of teleology, and that way lies error, endlessly compounded.
We now have the ability to selectively delete individual characteristics from many different organisms. This makes possible something that natural selection does not: the precise determination of the selective “value” of particular characteristics. This has already been done, and the surprising outcome has been that even some gene sequences that were thought to have been very important in selection (due to having been “conserved” over deep evolutionary time) are apparently insignificant or useless. We know this because knocking them out of the genome has no discernible effect on the survival or reproduction of the “knock-out” progeny.

Precisely my point, above.
That interpretation seems to depend on the hidden assumption that the environment hasn’t changed significantly in the recent history of the organism, and that the experimental environment is fully representative of the historical environment over the entire time during which the features in question evolved. In the case of knocked-out sequences that have no apparent effect on fitness, how sure are we that the experimental environment is fully representative in this way?

No, but to assume that we are making the opposite mistake - assuming that some characteristic really has some function, even if that function is entirely unobservable - is once again to fall into the “teleology trap”. This is essentially the same argument that ID people make about “junk DNA”. Just because we haven’t found any function for it, doesn’t mean that all of it has no function. They argue that all of it must have some function. They are, like the evolutionary biologists for whom Williams, Gould and Lewontin, and Gould and Vrba wrote their warnings about, assuming teleology in evolution: they are, in a word, “pan-adaptationists”.
As a hypothetical example, imagine a bacterial DNA sequence that is expressed only during the formation of spores to protect the organism during periods of extreme environmental conditions. Knock out the sequence and test the viability of the resulting variant. If the experimental environment doesn’t include the extreme conditions that induce spore formation, the organism will never attempt to express the knocked-out sequence, and so its absence will not be noticed. If the experimenter concludes that the sequence is insignificant or useless, she is mistaken.

True, but I would strongly prefer that adaptation be considered a “diagnosis by exclusion” rather than our first and most important resort. By focusing on adaptation and natural selection, we teeter on the edge of the “teleology trap” and often (maybe even usually) fall in, despite our best efforts to avoid doing so.


As always, comments, criticisms, and suggestions are warmly welcomed!


Labels: , , , , , ,

Wednesday, April 22, 2009

Why Intelligent Design Supporters Insist That ID Must Be True

It has taken me a very long while, but I think I finally understand why Intelligent Design (ID) exists, why websites like Uncommon Descent exist, and why the regular commentators who support ID at those websites are so determined to assert the absolute reality of ID, in spite of a complete lack of empirical evidence.

It’s all right here in this quote about the ultimate justification for morality:
“Of course [the validity of an objective moral code] is all dependent upon the truth of the existence of God and the truthfulness of scripture - most of us here are aware of that.”

I believe that this is the crux of the whole science versus ID debate: if there is no empirical evidence for the existence of God, then it all comes down entirely to pure, unsupported supposition. Yes, one can assert that God exists, and can assert that therefore whatever God asserts must, by definition, be the absolute objective truth, but by the standards of scientific logic (which are now almost universally accepted as providing the most reliable evidence for descriptions of reality), arguments based purely and solely on assertion are no longer considered valid.

Ergo, without some independent source of evidence – independent of the original assertion, that is – then it all comes down to dueling assertions, which means that eventually it all comes down to force majeure: whoever can make the most forceful assertion gets to define the Truth.

Therefore, there must be some kind of empirical evidence for the existence of God. The fact that no one has ever found any is completely irrelevant, and will remain so indefinitely. It also explains why it is perfectly legitimate to deliberately distort, misinterpret, omit, or otherwise alter empirical evidence if it does not support the otherwise unsupportable assertion that God exists. [1]

Here is the way it looks to me:

Condition #1:

• If a moral code is not objective, it is ipso facto invalid.

• The moral code asserted by God is the only objective moral code. [2]

• If God does not exist, then there is no basis for the assertion that there is an objective moral code.

• Therefore, if God does not exist, anything is permitted.

Condition #2:

• An argument supported purely by assertion(s) is invalid. [3]

• Ever since Francis Bacon’s Novum Organum, it has generally been considered necessary that there should be empirical evidence (either direct or indirect) in support of arguments.

• Ergo, there must be empirical evidence in support of the assertion that God exists. Otherwise, there can be no objective morals, and therefore anything is permitted.


Since God must exist (otherwise there are no morals and anything is permitted), then there must be empirical evidence for His existence. Finding none, it is therefore necessary to pretend that some exists, or to make some up. Otherwise there can be no objective basis for morals, society will necessarily collapse into chaos, and we will all inevitably become insatiable, maniacal, cannibalistic, orgiastic mass murderers, rapists, and thieves.

It also seems to me that this is the reason why ethical philosophers now virtually unanimously agree that ethical prescriptions cannot be derived from statements derived from empirical science (i.e. "ought" cannot be derived from "is"). To do so not only conflates two separate domains of logic (i.e. deductive versus inductive), but also requires that there be empirical evidence for something (i.e. ethical prescriptions) that are not and cannot be justified by empirical analysis (i.e. the workings of nature). Yes, we can use empirical analysis to determine if our ethical prescriptions have brought about the goals which we have decided to pursue, but we cannot use empirical analysis to formulate those goals.


[1] Unsupportable on the basis of empirical evidence, that is.

[2] An obvious corollary to this is that each and every one of God’s moral prescriptions is both objective and absolutely True, by definition. Hence the argument that anything God prescribes (such as the massacre of the Canaanites) is morally right, simply by virtue of His saying so.

[3] To be specific, arguments based purely on deductive (i.e. Aristotelian) logic have been largely superseded by arguments based on inductive logic.


As always, comments, criticisms, and suggestions are warmly welcomed!


Labels: , , , , , ,

Monday, April 20, 2009

Evolution: Is Free Will An Illusion?

Every summer I teach a seminar course at Cornell in which we examine the historical, philosophical, religious, and scientific implications of evolutionary theory. This summer our seminar course will consider the question: Is free will an illusion?

On the 15th of July, 1838, Charles Darwin began a notebook which he labeled as “M”, in which he intended to write down his correspondence, discoveries, musings, and speculations on “Metaphysics on Morals and Speculations on Expression”. On page 27 of that notebook, he wrote
“…one doubts existence of free will every action determined by hereditary constitution, example of others or teaching of others. (…man…probably the only [animal] affected by various knowledge which is not heredetary & instinctive) & the others are learnt, what they teach by the same means & therefore properly no free will. [Emphasis added]

In his private musing on the question of free will, Darwin came to the conclusion that human free will is an illusion, and that all of our actions (and, by extension, our thoughts and intentions) are the result of our “hereditary constitution” and “the example…or teaching of others.”

Some evolutionary biologists, notably William Provine of Cornell University, have followed Darwin’s lead and asserted that human free will is an illusion. Most philosophers disagree, asserting that free will is the principle difference between humans and non-human animals. Many Christian theologians go further, asserting that free will is the foundation of all human action, without which no rational ethics or theology is possible.

In our seminar course this summer we will take up this debate by considering two alternative hypotheses: (1) that human free will is real and forms the basis for our morals and ethics, or (2) that human free will is an illusion, the capacity for which is a product of the same evolutionary processes that have shaped our anatomical and behavioral adaptations. Included in this debate will be an extended consideration of the hypothesis that the capacity for ethical decision making is an evolutionary adaptation that has evolved by natural selection. We will read from some of the leading authors on both sides of the subject, including George Ainslie, Daniel Dennett, Robert Kane, Daniel Wegner, and Edward O. Wilson. Our intent will be to sort out the various issues at play, and to come to clarity on how those issues can be integrated into a perspective of the interplay between philosophy and the natural sciences.

Here are some particulars for the course:

INTENDED AUDIENCE: This course is intended primarily for students in biology, history, philosophy, religious studies, and science & technology studies. The approach will be interdisciplinary, and the format will consist of in-depth readings across the disciplines and discussion of the issues raised by such readings.

PREREQUISITES: None, although a knowledge of general evolutionary theory, evolutionary psychology, sociobiology, and the philosophy of human free will would be useful.

DAYS, TIMES, & PLACES: The course will meet on Tuesday and Thursday evenings from 6:00 to 9:00 PM in Mudd Hall, Room 409 (The Whittaker Seminar Room), beginning on Tuesday 23 June 2009 and ending on Thursday 30 July 2009.

CREDIT & GRADES: The course will be offered for 4 hours of credit, regardless of which course listing students choose to register for. Unless otherwise noted, course credit in BIOEE 4670 / BSOC 4471 can be used to fulfill biology/science distribution requirements and HIST 4150 / STS 4471 can be used to fulfill humanities distribution requirements (check with your college registrar's office for more information). Letter grades for this course will be based on the quality of written work on original research papers written by students, plus participation in class discussion. All participants must be registered in the Cornell Six-Week Summer Session to attend class meetings and receive credit for the course (click here for for more information and to enroll for this course). Registration will be limited to the first 18 students who enroll for credit.


Ainslie, G. (2008) Breakdown of Will, Cambridge University Press, ISBN: 0521596947 (paperback: $34.99), 272 pages.

Dennett, D. (2004) Freedom Evolves, Penguin Books, ISBN: 0142003840 (paperback: $17.00), 368 pages.

Kane, R. (2005) A Contemporary Introduction to Free Will, Oxford University Press (USA), ISBN: 019514970X (paperback: $19.95), 208 pages.

Wegner, D. (2003) The Illusion of Conscious Will, MIT Press, ISBN-10: 0262731622 (paperback: $21.95), 419 pages.

Wilson, E. O. (2004) On Human Nature (Revised Edition), Harvard University Press, ISBN: 0674016386 (paperback: $22.00), 284 pages.


Darwin, Charles (E. O. Wilson, ed.) (2006) From So Simple a Beginning: Darwin's Four Great Books. W. W. Norton, ISBN-10: 0393061345 (hardcover, $39.95), 1,706 pages. Available online here.

Fisher, J., Kane, R., Pereboom, D., & Vargas, M. (2007) Four Views on Free Will, Wiley-Blackwell, ISBN: 1405134860 (paperback: $33.95), 240 pages.

Kane, R. (2001) Free Will (Blackwell Readings in Philosophy), Wiley-Blackwell, ISBN: 0631221026 (paperback: $33.95), 328 pages.

Wilson, E. O. (2000) Sociobiology: The New Synthesis (25th Anniversary Edition), Belknap Press, ISBN: 0674002350 (paperback: $44.00), 720 pages

Our summer seminar course is always fascinating, and often quite controversial (see this and this). Over the years we have explored many of the implications of Darwin's theory, and the participants have always found our discussions (perhaps they should be called "debates") enlightening. As always, the intent is not necessarily to reach unanimity, but rather for each participant to come to clarity on where they stand on the issues and to be able to defend that stance using evidence and rational argument.

So, please consider taking our seminar on free will this summer - the choice is yours!


As always, comments, criticisms, and suggestions are warmly welcomed!


Labels: , , , , , ,

Tuesday, April 14, 2009

Evolution: The Darwinian Revolutions

Long-time readers of this blog will know that every summer I teach an introductory evolution course for non-scientists at Cornell. This year the focus of the course will be somewhat different. In honor of the bicentennial of the birth of Charles Darwin and the 150th anniversary of the publication of his monumental book, On the Origin of Species..., we will be focusing on the impact of Darwin's concept of evolution by natural selection, both on the sciences and on society as a whole.

Darwin's theory of evolution is the most revolutionary idea ever entertained by the human mind. It fundamentally alters our perception of reality. In profound and unsettling ways the theory of evolution changes our understanding of who we are, where we come from, why we do the things we do, and where we might be going. It does this by making us look carefully and dispassionately at the world around us, asking questions and seeking answers in the things we can observe.

This summer we will explore Darwin's theory and the impact that it has had on the sciences and on human society. Here is the syllabus for the course:

BIOEE 2070 / HIST 2870 / STS 2871
Cornell University Six-Week Summer Session – Summer 2009

PREREQUISITES: None - Intended for non-science majors with an interest in evolutionary theory

CREDIT HOURS: 3 (does not count toward evolution distribution requirement in biological sciences)

CLASS TIMES: Mondays and Wednesdays 6-9 PM, Monday 22 June 2009 to Wednesday 29 July 2009

CLASS LOCATION: Lectures in Morrison Room, Corson-Mudd Atrium. Discussions TBA in class.

COURSE FORMAT: The format for each class will be a two-hour interactive lecture/discussion, in which the professor outlines the major concepts, followed by a one-hour discussion section in which all participants present their interpretations and opinions of the concepts and readings under consideration. Participants will also have the opportunity to make full-length presentations of their original work. Grades will be based on the quality of three essays, due at the end of each two-week segment. Students may also opt to do one essay and a research paper (see description and point scores, below).

GRADE BASED ON: Attendance and participation in lecture and section, plus combined letter grade on three essays (suggested length = 4 to 8 pages) or one essay and one research paper (maximum length = 20 pages), for a total of 100 points (electronic/email submission encouraged, but not required)

COURSE DESCRIPTION: Evolution is the founding concept of the science of biology. This course examines evolution in historical and cultural contexts. Aims of the course include understanding the major issues in the history and current status of evolutionary theory and exploring the implications of evolution for culture and human psychology. Issues range from controversies over mechanisms of evolution in natural populations to the philosophical implications of evolutionary theory.


Darwin, Charles (E. O. Wilson, ed.) (2006) From So Simple a Beginning: Darwin's Four Great Books. W. W. Norton, ISBN: 0393061345 (hardcover, $39.95), 1,706 pages. Available online here

Goldschmidt, Tijs (1998) Darwin's dreampond: Drama in Lake Victoria, MIT Press, ISBN: 0262571218 (paperback, $27.00), 274 pages.

Jabloka, Eva & Lamb, Marion J. (2006) Evolution in Four Dimensions: Genetic, Epigenetic, Behavioral, and Symbolic Variation in the History of Life, MIT Press, ISBN: 0262600692 (paperback, $19.95), 474 pages.

Raup, David M. (1991) Extinction: Bad genes or bad luck? W.W. Norton, ISBN: 0393309274 (paperback, $14.95), 228 pages.

Ruse, Michael (2004) Darwin and design: Does evolution have a purpose? Harvard University Press, ISBN: 0674016319 (paperback, $19.50), 371 pages.


Darwin, Charles (1892) The autobiography of Charles Darwin (Nora Barlow, ed.), W.W. Norton, ISBN: 0393310698 (paperback, $14.95), 365 pages. Available online here


All of the course packet readings listed below are available from the course website. The password to access the course packet is “evolutioncp” (without the quotation marks). Alternate weblinks are provided for your convenience.

NOTE: Students will not be required to read all of these articles. Your instructor and/or TA will tell you which articles you are responsible for.

Ayala, F. (1970). Teleological explanations in evolutionary biology. Philosophy of Science, vol. 37, pp. 1–7.

Behe, M. (2002) Intelligent design as an alternative explanation for the existence of biomolecular machines. Unpublished manuscript.

Cosmides, L. & Tooby, J. (1997) Evolutionary psychology: A primer. Center for Evolutionary Psychology. Available online here

Dembski, W. (2005) What every theologian should know about creation, evolution, and design. Orthodoxy Today. Available online

Dobzhansky, T. (1973) Nothing in biology makes sense except in the light of evolution. The American Biology Teacher, vol. 35 (March 1973), pp. 125–129. Available online

Eldredge, N. and Gould, S. J. (1972) Punctuated equilibria: An alternative to phyletic gradualism. In Schopf, T. J. M. (1972) Models in Paleobiology, Freeman, Cooper, & Co., pp. 82–115. Available online here

Gould, S. J. And Lewontin, R. C. (1979) The spandrels of San Marco and the Panglossian paradigm: A critique of the adaptationist programme. Proceedings Of The Royal Society of London, Series B, vol. 205, no. 1161, pp. 581-598. Available online here

Huxley, T. H. (1860) Letter to Charles Kingsley, Available online

Jenkin, F. (1867) Review of Origin of Species. The North British Review, June 1867, vol. 46, pp. 277-318.
Available online here

Kaviar, B. (2003) A history of the eugenics movement at Cornell. Unpublished manuscript.

MacNeill, A. (2004) The capacity for religious experience is an evolutionary adaptation for warfare. Evolution and Cognition 10:1, pages 43 to 60.

MacNeill, A. (2005) Natural selection, sparrows, and a stochastic God. Available online here

MacNeill, A. (2006) Vertical polygyny in modern America: An evolutionary perspective. Available online here

Mayr, E. (1974) Telological and teleonomic: A new analysis. Boston Studies in the Philosophy of Science, XIV, pages 91 to 117.

Mayr, E. (1982) The growth of biological thought. Harvard University Press. Chapters 12 & 13, pages 535 to 627.

Pinker, S. (2004) The evolutionary psychology of religion. Freedom From Religion Foundation. Available online here

Wegner, D. (2002) The illusion of conscious will. MIT Press: Cambridge. Chapter 3, pages 63 to 98.

The science of evolutionary biology began with the publication of Charles Darwin's On the Origin of Species. It is one of the most important books ever written and should be read by any person who wants to understand who we are, where we come from, and why we are here (and how we know).

Darwin's theory was accepted by most scientists of his generation within a surprisingly short time. Then, within just one more generation, it fell out of favor, replaced by genetic theories of evolution suggested by the rediscovered work of Gregor Mendel. Then, in another generation, the pendulum swung the other way, and Darwin's ideas were integrated with Mendel's and codified in the "modern synthesis."

Evolutionary theory has exploded in the fifty years since the "modern synthesis" was proclaimed. Sociobiology, punctuated equilibrium and new ideas about evolutionary psychology, genetic engineering, macroevolution, speciation…these are just a few of the directions that evolutionary theory and biology have expanded in the second half of the 20th century and the beginning of the 21st.

I would like to invite anyone who has found this blog interesting to take this course, or follow along with us by keeping up with the course materials posted at the course website. Either way, you will find your mind being stretched and your view of reality challenged. What better way could one spend a few summer evenings?

See you this summer!


As always, comments, criticisms, and suggestions are warmly welcomed!


Labels: , , , ,

Wednesday, April 08, 2009

Platonic Ideal Forms Versus Evolutionary Developmental Biology

In a recent thread at Uncommon Descent,
Salvador Cordova
"[The existence of] platonic forms would strongly suggest that [evolutionary] transitional [form]s don’t exist. And if there are only lawful morphological forms, transitional forms, even in principle, couldn’t exist. Transitional forms and Platonic Forms don’t fit well together in any theory. It appears the two are mutually exculsive.

In engineering we have many platonic forms. As engineers we are taught to recognize and implement certain canned architectures. A lot of systems biology is mapping biological forms to the forms engineers recognize.

[The] quest for “correct designs” ... makes sense in a world of ideal forms, platonic forms. We instinctively have platonic forms in our mind. We have a sense that a defect is a defect, that an error is an error.

In the Darwinian world, it’s all about selective advantage. A blind cave fish is “selectively advantaged”. Defect is only a relative term. However in the eyes of plato, a blind cave fish is less than the ideal, it is a broken form. In such case, natural seleciton helped to infuse the defect in the population and thus introduce a defect that is not consistent with the ideal pattern.

The notion of platonic forms does not seem to be compatible with Darwinian evolution. [Emphasis added]

The idea of Platonic ideal forms in biology is an old one. The now mostly defunct tradition of orthogenesis is essentially a version of Platonic ideal forms applied to biology (and an argument can also be made that Lamarck’s progressive theory of evolution by means of the inheritance of acquired characteristics is as well). However, and contrary to what some might expect, applying the concepts of orthogenesis to "intelligent design theory" ("ID") is problematic, because in its early 20th century form, orthogenesis was considered to be progressive, but not goal oriented (i.e. teleological).

In addition to the early orthogenesists, two other names stand out in this tradition: D’Arcy Thompson and Stephen Jay Gould. Both were primarily concerned with the origin and evolution of form, and both developed theories of evolution based on this. Even J.B.S. Haldane (one of the founders of the “modern evolutionary synthesis”) wrote in this tradition in his essay "On Being the Right Size". Haldane’s musings on the relationship between size and constraints on form have become known as “Haldane’s Principle”, and have recently been applied to urban planning.

The newly emerging science of evolutionary developmental biology (”evo-devo”) has some similarities to orthogenesis, especially insofar as both are attempts to explain why the evolution of overall form (i.e. phenotype) appears to be constrained to certain types of forms, rather than all possible forms. The orthogenesists asserted that there are certain forms that are much more likely than others. These forms are similar in some ways to Platonic forms, in that there is no necessarily materialistic explanation for the predominance of certain forms, at least according to the theory of orthogenesis.

Evo-devo explains the similarities within “formal types” with reference to shared developmental programs, especially among eukaryotes. This shared developmental programming is based on the hierarchical gene regulation systems, most of which are based on homeotic gene regulatory mechanisms. Similar developmental constrains appear to exist among plants and fungi, but not so much among prokaryotes and multicellular protists. So, looking for things that resemble Platonic ideal forms in biology will probably involve identifying and categorizing the various developmental “channels” which are produced by these homeotic gene regulatory systems.

None of this, of course, says how the various hierarchical gene regulation systems originally evolved. This is another of those “deep time” problems, such as the origin of life and the origin of the genetic code. As I have commented repeatedly in the past, I believe that questions about such origins are almost certainly unanswerable using current empirical methods.

I also personally believe that the question of the origin of Platonic ideal forms (if such things exist and are empirically distinguishable from the various “channels” produced by the action of homeotic gene regulatory mechanisms) is both an open question and one that is almost certainly not answerable using empirical methods.

For more on the question of Platonic forms in biology, see this and this.

For a critique of my analysis of Platonic ideal forms in biology, see this.


As always, comments, criticisms, and suggestions are warmly welcomed!


Labels: , , , , , , , ,