Book Review: Michael Behe’s Darwin’s Black Box
by David Fleischacker
I have been enjoying Michael Behe’s book Darwin’s Black Box (first published in 1996, with an update in 2006). It brings out a significant challenge in thinking through evolution and so it is worth reading. However, I do not agree with his ultimate conclusion or even his explicit criterion for validating his argument. The central point of his argument is that once one turns to the molecular and biochemical understanding of organisms, one finds systems with an irreducible complexity that could not result from the gradual steps of evolutionary development. In addition to his presentations of specific biochemical systems that are irreducibly complex, Behe supports his position with the lack of any serious biological arguments that explain such gradual steps that construct these complex biochemical systems.
The merit of his book is that it does raise the validity of evolutionary theory in light of the developments taking place within biology due to studies in biochemistry. Behe does recognize the provisionality of his argument at times though at other times he presents his conclusions with complete certitude. As well, he recognizes that his insights regard only some biochemical systems, and not all. He does acknowledge that some systems at the molecular level can be explained by evolution so he does not consider his focus to be a comprehensive theory of organic life, but rather a focused inquiry that has ramifications for both intelligent design and for the explanatory scope of evolutionary theory (which he thinks is more limited than the field of biology recognizes)
At the same time, I would argue that the argument suffers a bit. Behe argues that a number of complex biochemical schemes are irreducibly complex. Irreducibly complex means that key parts of a system contribute to the whole system and that removing any of the parts results in the loss of the function of the system as a whole. This functional whole seems to refer to two possibilities. In one case it is like a scheme of recurrence in which the main focus is upon one of the events in the scheme that is crucial for organic function, such as is the case of ATP in Kreb’s cycle within mitochondria. ATP is one of the molecules constructed in the scheme of recurrence that we call Kreb’s cycle, and because it is a central energy molecule, it is crucial for many processes in the cell, and thus is sometimes referred to as the functional reason for the whole of the cycle. Another meaning to functional whole however is what Lonergan would call the higher conjugate form that is built upon a lower matrix of conjugate forms (see explanatory genus and species in Insight – chapters 8 and 15). So, something like an immune response is a conjugate form that exists within an aggregate of genetic/biochemical events. In both cases take away one of the “parts” — which could be an event within a scheme or an event within an aggregate that constitutes a lower level matrix for a higher conjugate form–and the “functional whole” is lost.
Irreducible complexity alone is not an argument against evolution. Part of the suffering is that it lacks an adequate account of the heuristic structures operative in biology and the isomorphic metaphysics that is implicit in those structures. Key that is missing is the shift from descriptive definitions to implicit definitions, and then how this shift moves into an explanatory horizon that then begins to move into an explanatory account of development, whether of single organisms or organisms within ecological relationships.
Why is the shift from description to explanation such a key piece that is missing in his arguments? Because evolutionary theory was initiated from a series of descriptive traits that had been observed by Darwin and Wallace (and earlier folks who developed different explanations). Descriptive knowledge identifies characteristics and activities of things through conjugates that are derived from the senses. So, the blue bird has certain colors and shapes that are used to describe its bodily features, colors and shapes that derive their meaning from a relationship between the bird and our senses. Our senses are attuned to a rather large range of objects in our spatial-temporal world. We can see shifts in light patterns with our eyes (and of course the associative cortices and the sensory cortex involved in constructing the input that comes through the eyes), which we can articulate as colors or shapes or sizes. We can hear shifts in auditory sound waves with our ears. We can smell patterns and changes of the chemicals that are found within our atmosphere through our noses and the chemical make-up of solids, liquids, and even gases that touch the sensory neurons of our taste buds. Through touch we can feel textures and contours and temperatures. All material objects that have a certain mass size can be detected by our senses. Many physical objects in our world fall within our sensory capabilities. So, when we talk about descriptive knowledge, one of the elements that Lonergan recovers against modernity is the degradation of such knowledge. It is not imaginary. It has a validity to it and a crucial place in our lives.
Behe does seem to suffer a bit from this modern mistake. Descriptive knowledge is not false or misleading. It is incomplete of course, but it is true as far as it goes. This happened in physics. Copernicus argued that the sun no longer goes around the earth. But, now one can admit that because of relativity Copernicus was not right, at least entirely. The sun does rise and set when one sets the frame of reference (the X, Y, and Z of a three dimensional manifold — and one must also include t as a fourth dimension) as one’s own sensory framework, or even the earth. It is not that Copernicus was entirely wrong. One can set the sun as the center of that frame of reference. Or one can set the center of the Milky Way galaxy (presumably a black hole). Behe seems to want to say that in this more primitive descriptive world, one might come up with the idea of evolution, however, when you move to the “black box” of molecular and biochemical explanation, then one moves to reality and away from myth. I say “seem” simply because of his phrase “black box” though he does not explicitly say that the data of Darwin was unreal. One correction here is to suggest that discoveries made through descriptive knowledge do have their relevance when put within the right frame of reference. Behe does not adequately deal with the kind of descriptive knowledge that is involved in validating evolution (or the modern synthesis that integrated Mendel and Darwin, since it falls within the realm of explanation constituted by explanatory rather than implicit definitions — see chapter 1 of Insight).
Furthermore, scientific description is not merely another frame of reference based on the relations of things to us, but it is the way that science both collects its data and verifies its theories. Concrete inferences of laws–whether classical or statistical or developmental–all require implementing and verifying those laws through descriptively articulated data. Ultimately, scientific description and scientific explanation are complementary to each other. What is discovered and proposed in one cannot ultimately conflict with the other if they are both true (or converging provisionally upon what is true).
With regard to biology, I would argue that many do not adequately understand the stage of development in which it currently resides. This is largely due to the complexity of the field. Organisms as Lonergan outlines in Insight, chapter 15, require that one shift into a grasp of operators and development. And these only arise after one has introduced correlations and statistics. Furthermore, there are preliminary stages within the descriptive world. There are descriptive conjugates that are preparatory for explanatory conjugates. Describing what happens when liquids are mixed or when objects are projected or when the planets move in their orbits prepares the way for the world of correlations. Describing whether something happens for the most part, or infrequently, or all the time prepares the way for ideal frequencies whether these are based on descriptive, explanatory, or implicitly defined conjugates. And with regard to development, one gets a sense that things grow and change in their descriptive conjugates before one discovers the operators that transform one system of conjugates into another.
At this stage in the development of biology, at least over the last century, I would say it largely resided within the world of explanatory definitions. In an explanatory definition, one of the terms is descriptive, the other is explanatory. One good example of this is Mendel. Notice that his theory of genetics incorporated one descriptive term, and one explanatory term. Phenotype is descriptive. Genotype is explanatory (he use the term hereditary unit). However, later in the century, genetics moved to implicit definition through Watson and Crick, who related genes to proteins (three nucleotide sequences are paired to an amino acid — the building blocks of proteins). Since their introduction of this implicit definition, there has been a vast expansion taking place.
Evolutionary theory when it was first introduced was like the explanatory definition. All of the traits mentioned by Darwin are descriptively understood. As such, they had not reached the level of explanatory definitions, let alone the level of implicit definitions. So what makes it like explanatory? Well, he identified a number of descriptive conjugates that seemed to be related across species through some kind of parental origin. Notice, this springs from a recognition that organisms do come from other organisms (progeny come from parents), and that progeny are never exactly the same as the parental organism (s). It is important to note that there is not a clear sense that evolution results or can result in development. Rather, it is the emergence of an adaptive, and advantageous, change.
In the early 20th century, Evolution moved into another explanatory level with the modern synthesis. Once Mendel was discovered, Evolutionary theorists went to work to integrate Mendel’s breakthroughs. That synthesis was largely generic and heuristic because now biological explanation had to incorporate genetics. This synthesis took another leap once one introduces molecular and biochemical analysis into the science. I would argue that this latest synthesis shifted the images in which biology operates, and this shift has allowed for recognizing new patterns that constitute organic life, and these patterns are defined implicitly. Watson and Crick provide only one example.
What Behe catches upon is that the theories that had largely been developed from descriptive understandings of traits seem rather shaky in light of the shifts to molecular/biochemical accounts of the organism. He is right in a certain manner. The complexity of biochemical pathways involved in a number of organic activities are mind boggling. It is hard to fathom how these could have developed. Behe argues that these are impossible to account for in some kind of evolutionary development.
Where I think he has been mistaken is thinking that one should be able to develop an evolutionary theory of a biochemical process at this stage in the history of the field of biology. In the transition from explanatory to implicit definitions, it is natural that one first has to development a viewpoint that is constituted by implicit definitions which is adequate before one could then begin grasping the operators that unfold a deductive or homogeneous expansion, or a vertical expansion.
Another element that is missing from Behe, and nearly all other biologists or chemists, is the shift from lower levels of organic life to higher genera of sensate and rational life. This shift is far more difficult than from simple to complex organic processes (a horizontal shift). These are shifts from a lower to a higher level genus. These vertical developments add a new meaning to the complexity of evolutionary development. If Behe understood Lonegan’s articulation of higher and lower genus and species, he could strengthen his argument more. But then he might also have the breakthrough into generalized emergent probability as well, which would, at minimum, severely modify his view of biochemistry and the basis of his entire argument. I say at minimum because the argument of evolution is still an argument based on evidence, hence one of fact, even if it never rises beyond a provisional analytical principle.
So, what would the shift to biochemical images and implicitly defined organic conjugates do to the validity of evolution? I think it does weaken it a bit in terms of the degree of certainty that many hold evolution today. Largely, it still is at the stage of an explanatory definition. Its terms and its evidence are descriptive conjugates. We are a long way from reaching the periodic table of organic life. The traditional set of organic charts (kingdom, phylum, class, order, family, genus, species) are based on descriptive traits, though these are being modified daily as a result of biochemistry, molecular biology, cellular biology, and genetics into “evolutionary trees.” We are even further from developing an adequate set of developmental operators of individuals, species, and genii. In reality, biologists really do not have an explanatory or an implicit definition of species (notice that saying something is reproductively compatible is not saying “what” it is, hence they have not articulated the key explanatory conjugates the form a species within the genera of organic/vegetative/cellular life).
However, just because the development of the discipline of biology is not yet beyond the explanatory definitions in the field of evolution (it has begun to move to implicit definitions in genetics and some other conjugates of biology), does not mean that the explanatory definitions are wrong. They are based on evidence. And hence, just because there seems to be some irreducible difficulties when one begins to examine biochemistry and molecular biology, that alone is not sufficient to reject evolution as a theory. One still has to explain heredity, the differences of progeny from parents, and the ramifications of these differences over time. Evolution is one way to do that.
As Pat Byrne in his essay on “Lonergan, Evolutionary Science, and Intelligent Design,” argues, one of the things that Behe is missing is a grasp of emergent probability [Patrick Byrne, Revista Portuguesa de Filosofia T. 63, Fasc. 4, Os Domínios da Inteligência: Bernard Lonergan e a Filosofia. / The Realms of Insight: Bernard Lonergan and Philosophy (Oct. – Dec., 2007), pp. 893-918]. Emergent Probability, as Byrne notes is ultimately derived from Lonergan’s cognitional theory, not from empirical theories in the sciences and hence it is relatively independent from the development of specific scientific theories. Relatively independent because it is developed from the actual methodological operations involved in the sciences. Cognitively and metaphysically, the classical and statistical heuristic structures point to the potential of a dynamically oriented developmental universe. Still, as Lonergan notes, one has to argue what in fact the universe is about. It does not need to be developmental or evolutionary. Darwin’s theory has gained much weight through evidence that supports a matrix of descriptive conjugates that relate parents to progeny through generations in an environment where adaptation is possible and probable. Molecular biology, genetics, biochemistry, and cellular biology are moving biology into the realm of a fully explanatory discipline that is built upon provisionally verified implicit definitions. This shift is and will continue to bring with it challenges to the old explanatory definitions that had emerged in the field, including that of Darwin and those who advanced his theory in the modern synthesis (note that this synthesis relied on Mendel, not Watson and Crick). A yet even newer synthesis is arising and Behe’s book highlights the challenges to evolution of this shift even if, in the end, Behe turns out to be wrong and that evolution will rise even stronger once the new explanatory biology matures. But then again, he could be right. Maybe evolution is not right. I tend to think the evidence supporting the explanatory definitions of evolution theory have a significant weight that is left untouched by Behe’s arguments, and thus provide a valid way of proceeding in biology as it unfolds its new image (symbolic constructs from biochemistry) that is underlying its shift to implicit definitions. I suspect evolution will rise more nuanced in the end, and more like emergent probability, and hence stronger in the end. There many reasons for this beyond biology as well. There is evidence for emergent probability, quite a bit. There are analogous types of developments in almost all other realms of being (human history, social development, dogmatic development, etc.)
As a note, I have not addressed Behe’s views on intelligent design. That is another discussion and has some serious defects I would argue. I just wanted to discuss his views of evolution at this point.
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