In this blog post, I will introduce the debate over whether evolution has a direction and whether it constitutes progress, focusing on the exchange between Gould and Dawkins that took place in ‘Darwin’s Table’.
‘Darwin’s Table’ presents a variety of discussions on evolutionary theory. In this book, the Dawkins camp and the Gould camp debate a total of five topics, one per day; the topic for the fifth day is precisely the relationship between evolution and progress—that is, whether evolution has a direction and whether it implies progress.
The Dawkins camp takes the pro-progress stance, arguing that the evolutionary process proceeds in a specific direction—such as an increase in irreversible complexity—and that progress is central to evolution. In contrast, the anti-progressivists on the Gould side argue that evolution has no direction and that the observed changes represent nothing more than an increase in diversity.
“Irreversible complexity,” one of the key concepts of the Dawkins camp, refers to irreversible changes that occur at major turning points in the evolutionary process. This means that once a lineage passes through such a turning point, it cannot return to its original state. For example, the transition from single-celled to multicellular organisms and the shift from asexual to sexual reproduction are cited as examples of changes that are difficult to reverse.
The Dawkins camp views complexity as increasing through such irreversible evolution and argues that lineages that have undergone several stages of irreversible change can be interpreted as “progress.”
In contrast, Gould’s camp proposes the “drunkard’s walk” model. Just as a drunkard walking forward may appear to be biased in a certain direction if one side is blocked by a wall, this is not an intrinsic directionality but merely a bias resulting from boundary conditions. Gould uses this model to explain that evolution is not inherently directional.
The Dawkins camp counters that if the movement of the wall in the “drunkard’s walk” model is understood as an irreversible change—such that the direction in which the drunkard moves is determined—then life, too, evolves toward increasing complexity. In other words, they point out the limitations of the drunkard’s walk model.
The crux of this debate can be boiled down to two main questions. First, does evolution have directionality? Second, is evolution progress? The attached essay, taking Gould’s perspective, answers the first question by stating that there is no directionality, and responds to the second question by suggesting that evolution can be interpreted as progress if viewed as “an increase in the inertia with which an ecosystem withstands external shocks.”
The author of the attached essay argues that evolution represents an increase in the breadth of diversity rather than an increase in complexity. His primary argument is that bacteria—which make up the majority of life on Earth—have not evolved significantly in essence. Therefore, he argues, it is unreasonable to generalize the increased complexity of certain lineages as a directional trend for the whole.
However, this argument misunderstands the position of the Dawkins camp. Dawkins focuses on competition at the genetic level and the transmission of genetic traits rather than on population size itself. Consequently, when discussing evolution, it is difficult to draw conclusions based solely on an absolute comparison of population sizes.
A likely counterargument is that, given the enormous population size of bacteria, there must be more bacterial genes overall. In response, the Dawkins camp points out that there are essentially two ways to preserve genetic traits: one is by increasing population size, and the other is by preserving the genetic traits themselves over a long period of time. Complex organisms with long lifespans can stably preserve genetic traits throughout an individual’s lifetime, which may give them an advantage in terms of the continuity of gene transmission. Therefore, both the number of genes and the survival period of those genes must be considered together.
The attached essay uses the degeneration of tapeworm legs as an example to argue for evolution toward reduced complexity, but it overlooks the fact that for such a case of degeneration to be meaningful, there must have been a prior stage of increasing complexity.
The Dawkins camp views parts not included in irreversible complexity—such as the evolution of legs—as capable of degeneration; therefore, the tapeworm example does not deal a significant blow to Dawkins’ position.
The final argument in the attached essay is that “if there is directionality, the future should be predictable,” but this is contradictory. This is because the essay acknowledges in its main text that predicting the future is difficult due to the interactions among various variables, yet simultaneously demands that the future be predicted based solely on evolutionary trends. Realistically, the demand to precisely specify which environmental changes will trigger which irreversible evolution is unrealistic. Consequently, the attached essay failed to properly refute “irreversible complexity,” a core concept of the Dawkins camp. Unless the anti-progressivist effort can undermine the concept of irreversible complexity by relying on Gould’s arguments, it will struggle to gain credibility. Whether anti-progressivists propose an increase in the breadth of diversity as an alternative or advocate for something else, the increase in irreversible complexity in certain lineages through natural selection appears to be an unavoidable fact.
