This is what a strawman looks like

This is another post about the stupidity of Intelligent Design Creationists. Stop reading if you don't need any more convincing.

Today is Darwin Day. It's the anniversary of the birth of Charles Darwin (Feb. 12, 1809 - April 19, 1882).

This is not a happy day for the Discovery Institute so they've put up a series of posts on Evolution News & Views (sic) to discredit Darwin and "Darwinism."

One of them is by the newly rejuvenated poster boy, Michael Denton: On Darwin Day, Darwinism Is Well Past Its "Sell By" Date. Here's the part I want you to see,

To understand the core weakness of the Darwinian worldview, it is important to understand what Darwinian natural selection requires. The process will work its magic, building up functional structures in organisms, only when two very strict conditions are met: First, the structure must be adaptive—that is, helpful to the organism in flourishing in its environment—and second, there must be a continuum of structures, functional all along the way, leading from an ancestor species to the descendent.

That is, the thing we are trying to explain must in some way help the creature survive, and between the creature and the creature's ancestor there must be a gradual change, each step of which is stable and enhances fitness, or success in reproduction.

Strictly speaking, that's a reasonable explanation of Darwinism as most evolutionary biologists understand it. But here's the problem. There aren't very many evolutionary biologists who are strict Darwinists these days even though there are many who tilt strongly in that direction.

Denton want his followers to believe that this is the standard view of evolution. He knows better. He is deliberately deceiving his followers by setting up a strawman.

Problem number one is that there are a great number of complex structures in nature that are not led up to by known functional pathways, and imagining what these pathways might have been is in most cases very hard. But this challenge is greatly compounded by an additional problem: that in many cases complex structures convey not the slightest evidence that they ever performed an adaptive function in putative ancestral forms. This may come as a surprise to the student of evolution. The trade language of biology has focused on the concepts of adaptation, fitness, and utility for so long that it has in a sense blinded us to the universe of apparently non-adaptive order that permeates the entire organic realm.

For example, what is the adaptive fitness of the shape of a maple leaf? Or the shape of any leaf, for that matter? Nor are examples of seemingly non-adaptive order limited to the shapes of leaves. Some of the best examples are embedded deep within the biological world -- among the characteristics that define and separate the basic kinds or types of plants and animals from each other.

The role of chance and accident in the history of life should be familiar to all students of evolution even if they don't completely adopt such a worldview. They aren't much of a student if the concepts I described in Replaying life's tape aren't well-known to them. They should have read the "Spandrels" paper as undergraduates.

Michael Denton knows about Stephen Jay Gould. He knows about neutral alleles and random genetic drift. I'm sure he's read the "Spandrels" paper and I know for a fact that Denton is familiar with Gould's ideas of contingency and unpredictability because he discusses them in his book Nature's Destiny (1998). Here's a passage from page 296 of that book.

The notion that the transition of life was directed of facilitated by the laws of nature is perfectly consistent with the biocentric model of nature. Indeed, in a biocentric universe, where all the laws of nature have their ultimate meaning in the existence of life, it is hardly conceivable that the origin of life would have been left to chance. From a teleological perspective, the origin of life must be viewed as something quite inevitable and built into the laws of nature from the beginning, just as were the properties of water and the mutual fitness of DNA and protein and all the other coincidences in the physical and chemical properties of life's constituents.

Curiously, many biologists are willing to accept the possibility that the origin of life might be built in but not the subsequent path of evolution. For example, Stephen Jay Gould, in a recent article entitled "War of the World Views" in the journal Natural History, proposes, "that the simplest kind of cellular life arises as a predictable result of organic chemistry and the physics of self-organizing systems but that no predictable directions exist for life's later development." (My emphasis.) But surely it is far more likely that, if the chemical evolution of the first cell was built in, then the far less complex process—the biological evolution of life—will also turn out to be true.

It's inconceivable to me that Denton could discuss Gould's worldview without realizing that he is not the kind of strict Darwinist described in his latest post. He knows that the standard view of biologists is that the history of life is not just the product of natural selection as he makes out to his readers. In fact, Denton even admits this on page 16 of Nature's Destiny when he says, "The prevailing view within the biological sciences is still that life and man are fundamentally contingent phenomena."

His post continues,

Consider the pentadactyl (five-finger) design of the tetrapod limb, witnessed in the human arm and leg: one bone (the humerus in the upper arm, the femur in the upper leg), two bones (the radius and ulna in your lower arm, the tibia and fibula in the lower leg ), five fingers and five toes. This unique design occurs in the fore and hind limbs of all tetrapod (four-limbed) vertebrates, including human beings.

It is clear that in all tetrapod limbs the same basic design has been adapted to very different uses. However, given that the adaptive forms of the fore and hind limbs differ to some degree in every known tetrapod, it is very difficult to explain how the underlying pattern could have been arrived at so as to serve some adaptive end in a hypothetical fore and hind limb of an ancestral tetrapod. The Darwinian explanation, attributing the underlying structure to previous rounds of natural selection, is self-evidently ad hoc.

If we can't explain what specific adaptive function the pentadactyl design serves in any known extant or extinct species of tetrapod, there are no grounds for the Darwinian claim that there was some hypothetical species in some hypothetical environment where this unique design did serve some mysteriously obscure adaptive function in both limbs. In this case, even "just so stories" can't legitimate the Darwinian account.

Denton could not possibly have missed Gould's essay on Eight (or Fewer) Little Piggies since it's a very well-known criticism of the very strawman that Denton is erecting. Allow me to repeat the quotation I posted yesterday to illustrate the conflict. Here's what Gould says in his essay,

Never apologize for an explanation that is "only" contingent and not ordained by invariant laws of nature--for contingent events have made our world and our lives. If you ever feel the slightest pull in that dubious direction, think of poor Heathcliff, who would have been spared so much agony if only he had stayed a few more minutes to eavesdrop upon the conversation of Catherine and Nelly (yes, the book wouldn't have been as good, but consider the poor man's soul). Think of Bill Buckner who would never again let Mookie Wilson's easy grounder go through his legs--if only he could have another chance. Think of the alternative descendants of Ichthyostega, with only four fingers on each hand. Think of arithmetic with base eight, the difficulty of playing triple fugues on the piano, and the conversion of this essay into an illegible Roman tombstone, for how could I separate words withoutathumbtopressthe spacebaronthistypewriter.

How could Denton be so dishonest? He's ignoring one of the most common views in evolutionary biology; namely, that there is NOT an adaptive explanation for five digits. It's an historical accident.

Why would he set up such a strawman version of evolution in his post if he knows better?

Denton continues,

The challenge to the Darwinian framework is not restricted to the tetrapod limb, but applies almost universally to a veritable universe of other novel structures—the insect body plan, the concentric whorl pattern underlying all flowers, and the enucleated red blood cell found in all mammals, which was the subject of my own doctoral work at King's College in London.

Contributing further to the challenge inherent in so much non-adaptive order are revelations from the new field of evolutionary developmental biology (evo-devo). We now know that the paths of evolution have been highly constrained by a set of universally conserved developmental genetic mechanisms that transcend any immediate adaptive utility. Moreover, evo-devo implies that in the case of many novelties, internal constraints have played a decisive role in evolutionary origins.

In my new book, I detail vast quantities of evidence from the most up-to-date scientific literature, all supporting the radical idea that Darwinism played a very minor role in the history of life, and that evolutionary biology in the 21st century will have to seek an entirely new causal framework.

If his new book is all about attacking a strawman version of evolution then why should any of us bother to read it?

Many leading evolutionary biologists have long rejected a strict Darwinian explanation for the history of life. They recognize that modern species are the product of highly contingent pathways that were subject not only to environment influences (mass extinctions) but also to the fixation of neutral and detrimental alleles giving rise to non-adaptive, and even maladaptive, structures.

This is the modern view that refutes Denton's claim of the inevitability of humans or other conscious beings. This is the view that replaying the tape of life will almost certainly result in a different outcome. There is abundant evidence to support such a view. It is non-Darwinian. He must know this. Why is he creating a strawman version of evolution?

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