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How Do We Know If Something in Nature Is Purposeful?

Jonathan Bartlett considered the question recently in Cambridge’s Behavioral and Brain Sciences journal

The traditional philosophical term for discussing purpose is teleology. But that is a broad term and it implies that purpose really exists; To avoid the suggestion that there is underlying purpose evident in the world of life around us, biologist Colin Pittendrigh (1918–1996) coined a new term, teleonomy. But does a name change solve any problems?

Jonathan Bartlett, one of our authors here at Mind Matters News, published a short commentary in Cambridge’s Behavioral and Brain Sciences on a fundamental underlying question: How do we know if something is purposeful?

Bartlett was responding to an article by Yohan John et al. That article starts out by making the point that “When a measure becomes a target, it ceases to be a good measure,” also known as Goodhart’s Law. The definition of teleonomy is “apparent purposefulness of structure or function in living organisms that derives from their evolutionary adaptation.” (Merriam–Webster)

That raises a question: If the definition of purposefulness is that it is only apparent, how would we know whether any apparent purpose is also actual?

Bartlett comments as follows:

… the discussion of teleonomy, although appreciated, falls short in two main areas. The first issue is that the authors do not address how one identifies purposes objectively in teleonomic systems. Without clear methodological principles, an investigator is in danger of assigning ad hoc purposes to systems. Thankfully, the philosophical literature provides some help. Mossio and Bich (2017) provide a solid means for practitioners to objectively identify at least some goals. They say that we can objectively classify a process as goal-directed if that goal requires the system to expend energy to accomplish and entails some aspect of maintaining the causal closure of the system.

Bartlett J. An updated perspective on teleonomy. Behavioral and Brain Sciences. 2024;47:e69. doi:10.1017/S0140525X23002868

Moving away from strict selectionism

A perspective that Bartlett wanted to add to the discussion is that the study of evolution is slowly moving away from strict selectionism — where survival of the fittest selfish genes is assumed to explain everything there is to know about the origin and development of life on Earth.

In fact, there are increasing calls from a number of quarters in biology for an extended evolutionary synthesis that recognizes that biology is not just an extended form of physics and selfish genes do not rule. As Oxford biologist Denis Noble put it recently in a paper in Nature, that view is “oversimplified and out of date.”
Taking that into account, Bartlett writes,

The second area of concern is that, although the authors actively work with the concepts of teleonomy, they seem to be unaware of the progress made in the relationship between teleonomy and evolution over the past decade (Corning, 2014). Although teleonomy was originally thought to not apply to evolution itself, modern work in teleonomy has actually emphasized its role in evolution (Corning et al., 2023). However, the perspective that the authors of the target article take on evolution is decidedly selectionist, and, although it pays some lip service to nonselectionist thinking, it does not actually incorporate any of it into the main body of work. The extended evolutionary synthesis, which has been gaining prominence in biological thought in recent years, is largely a phenomena unified by evolutionary teleonomy (Bartlett, 2017). I think an analysis of proxy failure in evolutionary dynamics informed by modern approaches to evolution would be informative.

Bartlett J. Teleonomy.

The history of life involves many processes other than strict Darwinian selection. It includes epigenetics (inheritance of acquired characteristics), horizontal gene transfer, devolution, and stasis (nothing much changes for tens of millions of years), to name just a few paths to change.

As the study of the history of life includes a broader range of factors than it did fifty years ago, we may see a range of new voices offering fresh perspectives.

Note: If you are wondering about the many different ways that groups of life forms can change over vast periods of time, you might be interested in What the Fossils Told Us in Their Own Words: “Actual genomes do not demonstrate the Tree of Life in the neat and orderly way that underlies Darwinian accounts of evolution. They could hardly be expected to do so, given the creativity many life forms exhibit with their own genes via natural genetic engineering, horizontal gene transfer, epigenetics, and a crowd of other mechanisms. The Tree of Life has become a bush or a circle of life.” (Denyse O’Leary)

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How Do We Know If Something in Nature Is Purposeful?