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God and evolution 3: The problem of purpose A

Last updated on 22 Jun 2018

The problem of purpose

When Darwin published the Origin, he was lauded by his Christian friend and correspondent Asa Gray, who wrote:

“…Darwin’s great service to Natural Science in bringing back to it Teleology: so that instead of Morphology versus Teleology, we shall have Morphology wedded to Teleology”

Darwin replied soon after in a letter:

What you say about Teleology pleases me especially and I do not think anyone else has ever noticed the point.

Gray later wrote a long essay arguing for an evolutionary teleology.  The term teleology means the study of the purposes of things, and we can just replace it with “purpose”.

Under Aristotle’s philosophy, there were four “causes” (or accounts, aitia) of why things occurred. They were: the material it was made of (material account), the thing that made it change (efficient account), the form it had (formal account) and what it was for (final account). Thus, a house might be made of brick, be built by artisans, have the shape of a box, and be for living in. Explanations in terms of “final causes” or goals or purposes were the stuff of science for the next two thousand years.

At the beginning of modern science, though, Francis Bacon wrote:

… the research into Final Causes, like a virgin dedicated to God, is barren and produces nothing. [The Advancement of Learning, 1605, book III, ch V]

Bacon’s barren virgin theme became the standard for most sciences thereafter, except in biology. Living things were thought by all to have purposes. The famous philosopher Immanuel Kant even went so far as to declare that there would never be a Newton of a blade of grass, because living things had “purposiveness” (Zweckmassigkeit) which could not be explained in physical terms.

The natural theology movement from the 17th to the 19th centuries attempted to explain living things in terms of the purposes for which they were made by God, and from this to uncover the aims God had. Unlike the modern intelligent design movement, rather than working from the appearance of design to proving God’s existence, they reasoned from the functions and roles of things to God’s nature and providence. This culminated in the work of authors like William Paley, who found design in everything based on the assumption of God’s goodness and plan.

There are two kinds of purpose in the tradition. One is the external purpose of God or Nature. The other is the internal purpose that things, especially living things, might have in their nature (entelechy), and drives them to their natural end. To illustrate the difference, external purpose might bring order to an otherwise unruly nature, by command or imposition. If the world tends to be chaotic, then God gives it a purpose by imposing harmony and order, a view that had a lot of traction in the early and medieval period of Christianity.

Internal purpose, however, implies that things are innately going to fulfil their purpose without any guidance. Evolution might be progressive towards some “Omega point” if living things have internal purpose. This view, too, has forerunners in the middle ages, and found its best expression in the work of Teilhard de Chardin, a Jesuit theologian of the early 20th century.

Both of these kinds of purpose are widely accepted in various theistic theologies. But the standard view, expressed by Aquinas, is that internal purpose is what God gave to things:

The natural necessity inherent in things that are determined to one effect is impressed on them by the Divine power which directs them to their end, just as the necessity which directs the arrow to the target is impressed on it by the archer, and does not come from the arrow itself. There is this difference, however, that what creatures receive from God is their nature, whereas the direction imparted by man to natural things beyond what is natural to them is a kind of violence. Hence, as the forced necessity of the arrow shows the direction intended by the archer, so the natural determinism of creatures is a sign of the government of Divine Providence.

External purpose is not the primary reason things have purpose, but a secondary reason. Roughly, if God has to intervene, then that is because he needs to cause something that would not have otherwise occurred.

The purposes of selection

Despite Darwin’s approval of Gray’s comments, natural selection was profoundly problematic for believers. It implied that the appearance of purpose in the living world was a byproduct on an unintelligent designer. Selection was simply a physical process that resulted in organisms and organs that were fit for the environment in which they lived. In short, Kant’s purposiveness was a byproduct of unpurposeful processes. Many believers felt this removed the natural world from God’s plan. It meant that God was no longer needed to explain why the world had harmony: things that were not harmonious (adapted) tended to die out.

So the real issue was this: natural selection involved purpose after and not before the adapted part evolved. Forethought implies God’s design, but if purposes can be evolved themselves, this means that what has happened had no general purpose, just lots of local little ones, and they might in fact be competing as well.

In short, natural selection delivers neither internal nor external purpose, because it doesn’t imply that the purpose is the result of a plan or goal. Progress towards goals therefore becomes a limited and immediate thing, not generaliseable.

In modern philosophy of biology, this gets called “teleonomic”, in which the purpose or meaning of some trait or gene has the “purpose” of doing what it does because it allows the organism that carries the trait or gene to survive and reproduce. The other two kinds of purpose are called teleology, as mentioned, and teleomatics. Teleology is purpose driven, teleomatics is rule following (law-driven behaviour) and teleonomy is purpose seeking. We can illustrate this with a diagram:

Where the pre-scientific, sometimes called “Aristotelian”, view held that the laws of nature (teleomatic processes) were the result of purpose, and so things had innate purposes (teleonomics), the Darwinian and modern view seems to hold that the laws come first, then things evolve that have purpose-like behaviours such as functioning parts, and then, and only then, are there goal seeking things like humans with plans and intentions. Purposes become a fact of nature, shrunk down from the global nature of things to a small part of things. Organisms have purposes because they evolved them, and there is no place in this conception of nature for teleology to be the driving force of the world. At least, that is how it is seen by those who think Darwinian evolution presents a problem for belief. This includes not only theists, but those who think theism is incompatible with science, such as atheists who are exclusivists, that is, think that science precludes belief in gods.

In the next post, I will look at how some theists have dealt with this issue.


  1. DiscoveredJoys DiscoveredJoys

    A fascinating series; I look forward to ‘the book’. I have a question though – is there a risk that the rule following ring of the Darwinian teleology implies more order in the natural world than actually exists? I’ve recently developed a mental tic of replacing ‘laws’ (or more exactly ‘Laws’) with ‘regularities’.

    After all, an individual can ‘follow all the laws’ of the population/environment yet still fail to breed due to chance – yet the traditional teleology is often inferred to contain some god principle whose ‘purpose’ cannot fail.

  2. John, thank you. I am looking forward to the rest of this series and the eventual book.

  3. Those 3 concentric circles are very helpful, although I think I’d characterize “teleomatic” as “exhibiting lawlike regularity” rather than “rule following” or “law driven”. My motivation in doing so would be to argue that it doesn’t really involve anything deserving the name “purpose”. Your three purposes seem to correspond to Dennett’s three explanatory “stances” — physical, design and intentional — and we might say the physical stance avoids all teleology because it never mentions anything like a goal.

    All the same, perhaps the word ‘represent’ is appropriate even for “teleomatic” connection, as when two types of event are linked in a lawlike way, an information channel might be said to exist between them.

    Interesting, thoughtful stuff. I look forward to more of it!

  4. John the Plumber John the Plumber

    I think it important to consider that laws tell us what cannot be rather than what can. (Apples cannot fall sideways.) If what DiscoveredJoys says is correct, that rule followoing in Darwinian teleology implie more order in the world than actually exists, then it would fail to follow whatever rules say that more order than there actually is, is not allowed. – When purpose is removed from the picture, then what is is as it is, because that is what is allowed by the rules. Anything different is not allowed. There can be just so much order and just so much disorder. If this were not so, then things would not be as they are.
    This seems to lead to the conclusion that to do something with purpose must break laws.
    This stage of the evolution of the universe chanracterised by the regularities we see around us, like suns planets and hippopotamus, suggests a teleological arrow (if there can be such a thing) towards order.

  5. mijnheer mijnheer

    Thank you for these very helpful distinctions.

  6. Great stuff, John. I hope you do write the book.

  7. Teleological conception, be it classical Aristotelian or Darwinian, has an older antecedent in the ancient Horites, priests who were devotees of Horus. Horus was said to have set the boundaries for the winds, seas, earth and sky. This applied also to the Biblical “kinds” and the term “horotely” refers to Horus.

    I enjoy your blog very much!

  8. Thought-provoking.

    Do you mean “byproduct of” rather than “byproduct on”?

  9. Hi John,

    Despite Darwin’s approval of Gray’s comments, natural selection was profoundly problematic for believers. It implied that the appearance of purpose in the living world was a byproduct on an unintelligent designer. Selection was simply a physical process that resulted in organisms and organs that were fit for the environment in which they lived. In short, Kant’s purposiveness was a byproduct of unpurposeful processes.

    Under the traditional view of teleology, as I understand it, physical processes (e.g. rocks falling to earth) were also seen as purposeful — i.e., “simply a physical process” does not mean “unpurposeful” for the traditional teleologist (like Aquinas).

    For this reason, it seems to me that the scientific finding of natural selection is only “profoundly problematic” when coupled with the Darwinian and modern (philosophical) view of purposes in nature.

    • Natural Selection cannot be posited as a “law” since there are many examples of the apparent unfit and poorly adapted surviving and even thriving.

      Aquinas read Aristotle’s teleology via Latin and recognized his element of horotely, though he would not have explained this in terms of genetic boundaries. Certainly Neo-Darwinians have chosen to overlook this.

      • Natural selection is not a law, but a model of what happens in populations when conditions are right.

      • Given the right conditions, it is a stochastic process. For example, if a new mutation arises in a species and that mutation has a 1% selective advantage, then the stochastic process of nature gives a 2% chance for the new advantageous mutation to fix.

  10. Also, apart from intervention, a mutation with a 1% selective advantage has a roughly 2% chance of fixation in any possible world that is capable of supporting evolutionary life. This is logically necessary. God Almighty could not change that probability.

    • By the way, the above concept about the probabilities of selective advantage is a mere deduction of the view that mathematics is the same in all possible worlds.

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