Extended Evolutionary Synthesis: Overlooked or Incommensurable?

The Extended Evolutionary Synthesis (EES) has gained attention in recent years for its potential to expand our understanding of evolution. However, researchers debate whether it offers a novel or incommensurable perspective versus the traditional Modern Synthesis. This article explores the key arguments surrounding the incommensurability issue, with a focus on Kuhnian incommensurability and its implications for future research in evolutionary biology.

Introduction to Incommensurability

The concept of incommensurability was introduced by Thomas Kuhn in his seminal work The Structure of Scientific Revolutions. Kuhn argued that scientific theories are not merely collections of statements that can be objectively compared. Instead, they are frameworks that provide scientists with a way of interpreting the world. If these frameworks are incommensurable, it becomes difficult to compare them on a rational basis.

The Modern Synthesis: A Dominant Paradigm

The Modern Synthesis is the prevailing framework in evolutionary biology. This paradigm, developed in the 1930s and 1940s, integrates Darwinian natural selection with Mendelian genetics. It is a robust theory that has proven highly effective in explaining the mechanisms of evolution. However, some researchers argue that the Modern Synthesis is outdated and needs to be expanded to encompass developmental biology, ecology, and genetics more comprehensively.

The Extended Evolutionary Synthesis (EES)

The Extended Evolutionary Synthesis addresses these gaps by incorporating a broader range of factors and concepts. Key among these are:

Niche Construction: The idea that organisms alter their environments, which in turn affects their evolution. Evolvability: The potential of an organism to evolve further, which is influenced by its genetic architecture. Genetic Assimilation: The gradual conversion of acquired characteristics into inherited traits.

Analysis by Massimo Pigliucci

Massimo Pigliucci, a philosopher of science, has argued that the Modern Synthesis and EES are not incommensurable frameworks. In a book chapter, he suggests that the EES is a business-as-usual extension of our current knowledge about evolution. However, this view has been challenged on several grounds:

1. Conceptual Change

Pigliucci’s analysis assumes that the EES is a straightforward extension of the Modern Synthesis. However, the EES introduces new concepts and principles, such as niche construction, evolvability, and genetic assimilation, which are not part of the Modern Synthesis. This fundamental conceptual change may render the two frameworks incommensurable.

2. Predictive Differences

Another issue is that the EES may lead to different predictions. For instance, niche construction may play a more significant role in the distribution of traits in nature. If true, this could result in substantial predictive differences between the two frameworks.

3. Evaluation Frameworks

If the EES is incommensurable with the Modern Synthesis, it raises questions about the methods by which we would evaluate it. Traditional standards of evidence established for the Modern Synthesis may not apply to the EES, complicating the evaluation process.

Conclusion: Limited Analyses and Future Prospects

While Pigliucci’s arguments are valuable, they fall short in several respects. His analysis does not adequately consider the implications of conceptual change, predictive differences, and the challenges in evaluating the EES. As such, the door remains open for further philosophical explorations into whether the Modern Synthesis and EES are indeed incommensurable.

The debate over the incommensurability of the Modern Synthesis and the EES is ongoing, with the EES gaining significant traction in recent years. Future research may provide more clarity on whether the EES represents a novel departure or an incommensurable framework, impacting the direction of evolutionary biology in profound ways.