This is an unusual book. First, it is unusual because it is a book about evolution that manages to avoid the theological polemics (on both sides!) soThis is an unusual book. First, it is unusual because it is a book about evolution that manages to avoid the theological polemics (on both sides!) so common whenever the topic of evolution arises. Second, it is unusual because it is a 30 year old book about the science of evolution that is still relevant today. It is the book about evolution that I wish I had read 30 years ago. My background is computer software design so my understanding of biology has not come easily to me. I started studying the subject about two years ago and the details still challenge me. And so I appreciated that the author kept the discussion at the level of basic science with few forays into the minutia of molecular biology. When he did need to present technical material, he explained it with analogy and sufficient definition, so that the lay reader could understand his points.
The book is still relevant today because the core contradiction in evolution has not been solved. That is why Denton calls it a crisis. He does not mean that evolution is wrong. He means that there are “inconvenient facts” that do not fit cleanly into the theory. His first point in the book is that experts know about these facts, but most take the conservative view that ultimately the inconsistencies will be fully explained by the core theory. But Denton is writing the book for the minority who think the core of the theory needs to be revised. He is calling for a “paradigm shift” in the popular terminology introduced by Thomas Kuhn in The Structure of Scientific Revolution (1962).
So what is the core paradigm of evolution theory? First of all, the core paradigm applies mainly to what is called “macroevolution.” Macroevolution refers to the large scale changes in living species that accrue over long periods of time and to the creation of new species. In contrast, microevolution is the evolution that can be observed over short periods of time, in the laboratory and in the field. Microevolution is subject to experimental verification and nobody doubts that it exists and is an accurate representation of the changes that all living populations undergo.
The problems arise when microevolution is extrapolated to macroevolution. The issues are traceable to Darwin and his insistence that “nature does not make a leap” (“Natura non facit saltum”). This expression was the common wisdom of Darwin’s time. Darwin might have first encountered the expression in Linneaus’ Philosophia Botanica (1778) or perhaps in his gatherings with the Linnean Society. But even if he didn’t encounter it there, the idea was common in the science of his times. Leibniz (1646—1716) used it as did Newton (1642—1727) in their co-invention of the calculus.
Math was not Darwin’s strong suit, but he was very knowledgeable about the Principles of Geology (1830--1833) written by Charles Lyell, the first volume of which accompanied him when he set sail on the HMS Beagle in late 1831. But it was Lyell’s second volume, which arrived in the fall of 1832 when Darwin was in South America that raised the question that would preoccupy Darwin after his return to England. Lyell raised the question of whether plants and animals changed along with the Earth’s geology. Lyell’s answer was “no,” but he had planted a seed. And Lyell’s insistence on gradualism must have made an impression on Darwin: it was key to Lyell’s theory that “causes now in operation,” in the terminology of his subtitle, can be used to explain the past.
Science applied to past events is very different from research into current phenomenon. One cannot observe the past or run repeated experiments on past phenomenon. But if the forces of nature are gradual, continuous, and uniform, then current forces of nature can be reasonably applied to past events. In other words, nature does not make jumps. And Natural Selection was a current force of nature. Darwin had seen it in action in the breeding of sheep—one of his uncles was a leading sheep breeder — although in that case the selection was intentional.
Some historians say that Darwin insisted on the principle of gradualism for theological reasons. The creationists of Darwin’s day invoked catastrophe theories to explain creation and the social movements in the 19th century were moving against the power of the church. Catastrophism relied on supernatural forces and Darwin certainly wanted to avoid any taint of supernaturalism. But, whatever the origin of the idea of gradualism, the science of evolution took a path that Darwin could not have anticipated.
In the late 19th century the mystery about how traits were inherited was partially clarified by the discovery of genetics. And in the 20th century the molecular basis of genetics was discovered in the structure and function of DNA. This meant that the science of evolution could be very rigorous about microevolution; it could be studied in detail at the molecular level. With these advances, macroevolution had to be extrapolated anew from the detailed understanding of microevolution. The answer was that genetic mutations were gradual. They had to be otherwise the reasoning about current forces could not be applied to past events! This translated into random mutations generally thought to be the result of copying errors as DNA is replicated.
In this book, Michael Denton focuses like a laser on this basic foundation of Darwinian Evolution: nature does not make jumps. He rigorously examines the gaps in nature and what they might mean for the theory. These gaps are well known. There are gaps in the taxonomy of species because species do not flow continuously from one to the other. Mammals have hair, birds have feathers, reptiles have scales, etc. The best representation for the different species is something called a “nested hierarchy.” In other words, species can be rigorously categorized by their features. The discontinuous categorization of species is supported by DNA evidence.
Secondly, there are gaps in the fossil record. Some of the nodes in the nested hierarchy can be associated with actual fossils, but most cannot. The fossils are missing. These gaps in the fossil evidence led Stephen J. Gould (1941—2002) and one of his students to propose a theory of Punctuated Equilibrium. In this theory, evolution of new species happens quickly but then each species stays constant for long stretches of time. Punctuated Equilibrium, if it is true, is neither uniform nor gradual evolution.
Finally, the genetics implied by random mutation cannot reasonably be expected to act quickly enough to produce the adaptive variations that we actually find. With over 3 billion letters in human DNA, if each mutation has an equal chance of occurring at each letter then the chance of an adaptive mutation is vanishingly small. Even the smallest bacterial organism needs about one-half million DNA letters. Adaptive mutations are as rare as the proverbial needle in a haystack based on the assumption of random mutation.
While the treatment of possible non-random processes for mutation was beyond the scope of the book, let me quote from University of Chicago microbiologist James A. Shapiro in his book, Evolution: A View from the 21st Century (2011):
It is difficult (if not impossible) to find a genome change operator that is truly random in its action within the DNA of the cell where it works. All careful studies of mutagenesis find statistically significant nonrandom patterns of change, and genome sequence studies confirm distinct biases in location of different mobile genetic elements.
Author Lee M. Spetner has proposed a theory of non-random evolution whereby environmental factors influence genetic change. This idea is based on the growing research into epigenetics.
In conclusion, Denton summarizes that the foundational assumption about nature not making jumps is flawed. There is no known law of nature that makes this assumption true. In fact, beginnings are known to be discontinuous. The universe had a discontinuous beginning 13.7 billion years ago and life is thought to have a discontinuous beginning over 3.5 billion years ago on Earth. Quantum theory requires nature to make jumps, albeit at small intervals. Cataclysmic forces are thought to have created Earth’s moon. There is no requirement for nature to be continuous, particularly nature applied to living organisms, all of which will ultimately cease to be alive.
However, until a new theory comes along, Darwinian Evolution is the best we’ve got. But in order for there to be a new theory, a paradigm shift has to occur. When this book was written in the 1980’s, too many specialists believed in random mutation for that to change. Perhaps Denton is at his best in explaining how scientific paradigms turn into dogma:
As the years passed after the Darwinian revolution, and as evolution became more and more consolidated into dogma, the gestalt of continuity imposed itself on every facet of biology. The discontinuities of nature could no longer be perceived. Consequently, debate slackened and there was less need to justify the idea of evolution by reference to the facts.
Increasingly, its highly theoretical nature was forgotten, and gradually Darwinian concepts came to permeate every aspect of biological thought so that today all biological phenomenon are interpreted in Darwinian terms and every professional biologist is subject throughout his working life to continued affirmation of the truth of Darwinian theory.
The fact that every journal, academic debate and popular discussion assumes the truth of Darwinian theory tends to reinforce its credibility enormously. This is bound to be so because, as sociologists of knowledge are at pains to point out, it is by conversation in its broadest sense of the word that our views and conceptions of reality are maintained and therefore the plausibility of any theory or world view is largely dependent upon the social support it receives rather than its empirical content or rational consistency. Thus the all pervasive affirmation of the validity of Darwinian theory has had the inevitable effect of raising its status into an impregnable axiom which could not even conceivably be wrong.
30 years later perhaps we are beginning to see this change as more specialists like Dr. Shapiro begin to question the dogmatic underpinnings of traditional evolution theory. In view of the ongoing criticism of the traditional theory, perhaps Denton’s book can even be called prophetic.
Thomas Nagel has written a book about the limitations of science. Nagel states that science has failed to understand its own limitations when spokespeThomas Nagel has written a book about the limitations of science. Nagel states that science has failed to understand its own limitations when spokespersons for science assert that consciousness can be explained by a purely materialistic and reductionistic approach. The problem began during the 17th century enlightenment when science began to focus solely on empirical evidence by setting aside the problem of mind, of consciousness, of the subjective perspective. While the discovery of empirical science sparked tremendous advance in technology and civilization, it did so at a cost: consciousness had to be assumed to go along for the ride as a separate phenomenon. René Descartes provided the inspiration for the much-hated Cartesian dualism with his famous dictum, “I think, therefore I am.”
So now when someone claims that science can explain consciousness by empirical methods focused solely on the material aspects of nature, they appear to be forgetting about the paradigm shift that took place on the 17th century. Nagel thinks that scientific materialism or reductionism has reached a dead-end when it attempts to explain consciousness. He thinks that a new approach is needed, a paradigm shift comparable to the one that took place in the 17th century.
Thomas Nagel is a philosopher who is writing about the limitations of science, so his authority to do so is a key question about this book. As he says in the Introduction, he is a “layman who reads widely in the literature that explains contemporary science to the nonspecialist.” Since he directs much of his criticism at the biological sciences where reductionism in the guise of Darwinian materialism has gained a dominating foothold, one can legitimately question Nagel’s credentials to criticize science. But Nagel thinks it is philosophy’s essential role to delineate the limits of what we know or can know about the world in which we live, so he takes on the risk of writing a controversial book.
Since Nagel does not attempt to marshal the scientific evidence for his perspective, the overall effect of the book is a kind of “emperor has no clothes” event. At times he appears naïve about the scientific evidence and seems to assume that readers will know about the evidence that has led him to this position and will see things the same way that he does. One critic has likened Nagel’s attempt to take on the entrenched Darwinian narrative as bringing “a knife to a shootout.”
Nagel’s attempt to challenge empirical science with philosophy may seem like he is ill equipped to handle to task, but he is not alone in his view that science is as concerned with correct understanding of the world as it is with empirical data and that sometimes the predominant understanding can be wrong as it has been many times in earlier ages. However, an argument that demonstrates a problem with a dominate paradigm cannot be the sole purpose for a serious writer. One must also propose a new way forward.
In proposing a new way to view the scientific evidence, Nagel comes up short. His proposal is “natural teleology,” which is the view that there is a natural bias towards life and consciousness in the laws of nature. He is absolutely clear that such a natural bias would not be the action of a divine power. Unfortunately, he does not attempt to provide any scientific evidence for this proposal. He says only that some radical change will be needed:
“[W]e should expect theoretical progress in this area to require a major conceptual revolution at least as radical as relativity theory, the introduction of electromagnetic fields into physics— or the original scientific revolution itself . . .”
Without a more specific proposal, the reader is left only with a suggested change to the scientific narrative without the underlying scientific ideas. While one might conceivably accept his proposal on philosophical terms alone, that is a major leap of faith for most secular-minded readers. And leaps of faith are exactly what secular-minded readers will want to avoid as such leaps invite too many comparisons to other faith-based alternatives.
What is surprising to me is that Nagel does not refer to the scientific suggestions for the origin of consciousness. Perhaps they are too speculative, but there have been many suggestions that consciousness derives from quantum action within the brain and nervous system. In fact, one of the earliest credible proposals was put forth by physicist Roger Penrose in 1989. Penrose’s book, The Emperor’s New Mind, was an earlier attempt to disclose the Emperor’s nakedness. Penrose’s target, though, was the artificial intelligence paradigm for consciousness.
The artificial intelligence narrative is based on the theory that consciousness is based solely on computation. Penrose thought otherwise and proceeded to argue that it is not logically possible for human consciousness to be based on computation alone. He also proposed a new way forward based on the science of quantum theory. Penrose’s argument has been criticized, but his proposal has sparked much research into the biology of quantum consciousness. That is how science progresses.
The problem with Nagel’s proposal is that it is too general to spark any new research. And without the detailed connection to the scientific evidence, the proposal lacks credibility. Since I have written so negatively about Nagel’s book, the reader might be surprised to discover that I mostly agree with Nagel’s philosophical conclusion. Despite that fact that Nagel has proposed an atheistic solution to the problem of consciousness, it is quite compatible with my theist views. Where Nagel thinks that teleology is the result of natural law, I believe that teleology is the result of God’s intention. I believe that divine power will better explain the full range of human subjective experience.
If I were an atheist, and I wanted to make a strong argument for the atheist position on consciousness, I would have written a book about how consciousness is the result of quantum computation. That position can be supported by the scientific evidence and it strongly shows the connection to physical law so that there is less opportunity to attribute consciousness to a divine power. That Nagel did not write such a book can be seen as a testimony to his unwavering sense of the expansive nature of subjective experience. He simply does not believe that consciousness can be the result of computation alone. To me that is the real value of his book. ...more
I was disappointed. I had expected more hard science and more detailed medical and biological evidence. The author chose to stay with big ideas such aI was disappointed. I had expected more hard science and more detailed medical and biological evidence. The author chose to stay with big ideas such as the inability of persons with certain medical conditions to control their behavior. The primary hard evidence that he gives against the proposition that we have free will is the Libet experiments from the 1970's. These experiments show that brain potentials rise before we are consciously aware of them and that our responses are likely the result of subconscious or unconscious brain activity. But without a scientific framework for consciousness, the experiments, by themselves, are ambiguous.
The main point of this book is to argue that our criminal justice system is flawed by the outdated concept to assess the blame of an individual in a court of law. Eagleman argues that the criminal justice system should be changed to assess how likely the individual is to be changed by treatment. This is an admirable goal, but there is little evidence presented that society can do any better at assessing an individual's ability to change. We await much medical research and development before accurate prediction can be any better than the determination of mitigating past conditioning.
Finally, after hammering the point over and over that we are essentially our biology, he lets us know that biology isn't the whole story and that environment is a key part of the narrative. He describes the nature versus nurture debate and how biological reductionism will not lead us to any better understanding of ourselves. He describes the principle of emergence but does not deal with the complex relationship between emergence and reductionism.
Ultimately he leaves us with the mystery of struggling with our own nature and the nature of the universe. But without a deeper presentation of the scientific evidence, we are left with few tools to explore this mystery on our own....more