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.
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.