There are different approaches towards the concept of “teleology” and in many ways it is related to a particular view or concept of “matter” and “change”. The Scholastic approach towards matter and change are described here and here. The approach is Aristotelian by nature. Darwin had good things to say about Aristotle. From Allan Gotthelf's article "Darwin on Aristotle": Darwin in a letter to William Ogle:
"Linnaeus and Cuvier have been my two gods, though in very different ways, but they were mere schoolboys to old Aristotle."
It is safe to say that Darwin did not model his concept of natural selection from an Aristotelian or Scholastic point of view as Gotthelf points out that Darwin was familiar with Aristotle's work but his respect for him only grew after he published The Origin. Mechanistic philosophy of matter and change was prevalent during Darwin's era. Paley's watchmaker analogy was the basis for the argument from design whereby reality was like a machine composed of parts with no intrinsic relationship between them. The designs in the system (or reality) were imposed from an outside agent.
Darwin came along and developed his concept of natural selection and attributed the designs in nature to be the result of natural selection. James Lennox argues that Darwin was indeed a teleologist ("Darwin was a teleologist") and as Ariew points out (in his article "Platonic and Aristotelian Roots of Teleological Arguments in Cosmology and Biology") it has to do with his particular conception of natural selection as some sort of “teleological force”. Like Paley, Darwin most likely had a mechanistic view of matter and he modelled his idea of natural selection on this view. Like Aristotle (as Ariew argues) Darwin's idea of natural selection preserves elements of Aristotle's final (functional teleology) and formal causes.
How is natural selection a teleological "force"? I see remnants of two sorts of teleology operating in Darwin. The key to seeing both is within DarwinÕs concept of natural selection which can be summed up as follows: as a result of individuals possessing different heritable abilities striving to survive and reproduce in local environments, comes an explanation for changes in trait composition of populations through time. Traits become prevalent in populations because they are useful to organisms in their struggle to survive. Aristotle's functional teleology is preserved through the idea that an item's existence can be explained in terms of its usefulness (Lennox 1993). What makes a trait useful is that it provides certain individuals an advantage over others in their own struggle to survive and reproduce. Secondly, the concept of individual striving to survive and reproduce plays the fundamental role in Darwin's explanation for the origins of organic diversity. The same concept reminds us of Aristotle's formal teleology – the striving for self-preservation.
However, Aristotle's formal and final causes where intrinsic features of substances and substances on this view where NOT mechanical parts of a machine whose actions were attributed to an outside/extrinsic force. Darwin's idea of natural selection seems to be some sort of force that is part of reality but extrinsic from the substances (or parts as per mechanistic philosophy) of reality.
Ed Feser (and Andrew Ariew in above mentioned article) on his blog (e.g. Teleology revisited, Four approaches to teleology, Final causality and Aristotle’s Unmoved Mover) and in his books also distinguishes between teleological eliminativism and teleological intentionalism and the different kinds (e.g. Platonic, Aristotelian and Scholastic).
From these different approaches one can start to draw a picture by connecting the different views of matter and teleology (Figure 1).
So there you have it, Darwin was a natural selection teleologist whereby natural selection is an extrinsic teleological force that preserves elements of Aristotle's functional teleology (final causality) and formal causality but based on a mechanistic view of matter.
Of course in evolutionary theory today natural selection is not described as some sort of cause or force any more. Instead, as pointed out natural selection is just a descriptive term to describe when you have individuals in a population that have some kind of variation and fitness differences and are able to pass on their traits.
Or are there people that seem to use natural selection as some sort of cause or force? Any natural selection teleologists around?
This is the end of the Scholastic P&M interlude (phew, you can relax, no more "navel-gazing" ). Let's get back to empirical science e.g. somatic evolution of cancer, preadaptations, drug design and evolutionary algorithms as well as other empirical science-related issues.
I suppose another kind of teleologist or teleological view can be that of the "Laws of Nature" teleologist whereby the laws of nature are prescriptive and the "laws of nature govern" metaphor is taken literally. Laws of nature on this view really govern this or that piece of matter in a normative manner that is extrinsic from matter (irrespective of the description of matter) itself. See figure 2.