Modern materialists reject both teleology in nature and (implicitly or explicitly) the existence of the mind as a power distinct from matter (in which they understand matter as quantity extended in space). This rejection, which is a profound error, has an interesting history.
Perhaps the turning point in modern philosophy of science was the abandonment of teleology by Francis Bacon in 1620 in his book Novum Organum Scientiarum. Bacon advocated the abandonment of Aristotelian teleological and formal explanations in nature, and advocated reductionist and inductive approaches to science. Bacon is generally considered to have provided the philosophical basis for the scientific method, although this claim is dubious given the scientific accomplishments of his predecessors and contemporaries (Albertus Magnus, Roger Bacon, Copernicus, and Galileo, to name just a few).
Francis Bacon’s rejection of teleology was an elaboration on the rejection of teleology by his contemporary Rene Descartes. Descartes abandoned Aristotle’s hylemorphism and proposed a material res extensa and immaterial res cogitans to explain man. But modern materialism isn’t the opposite of dualism, at least not the opposite of Cartesian dualism. Materialists are really Cartesians who delete res cogitans, and leave only matter — res extensa — to explain nature and to explain man. Materialists eliminate mind just as Bacon explicitly eliminated teleology from nature.
Materialists are the modern Cartesians, in the sense that they embrace without question Descartes’ res extensa and his segue away from teleology, completed by Bacon. In fact, the inherently Cartesian nature of modern materialism reasserts itself with the mind-body dichotomy that is central to modern debates on philosophy of mind. Although materialists propose to solve the mind-body dichotomy by eliminating the mind (implicitly or explicitly), the very framing of the question as “mind-body problem” is Cartesian. Aristotle and St. Thomas would have asked, of the mind-body problem, “What problem?”
In the hylemorphic perspective, the mind-body relationship is no more a “problem” than the form-matter relationship in a chair. Substances are composites of principles of intelligibility and individuation — form and matter. Their real existence is only as a single substance. Descartes created the mind-body problem, which modern materialists are trying to solve by embracing Cartesian metaphysics (usually without realizing what they are doing, which is their trademark), and eliminating the mind. Materialists basically embrace the worst metaphysical mistake of the past millennium — the abandonment of hylemorphism, and make it worse.
From the hylemorphic perspective, there is an intimate link between the mind and teleology. The 19th-century philosopher Franz Brentano pointed out that the hallmark of the mind is that it is directed to something other than itself. That is, the mind has intentionality, which is the ability of a mental process to be about something, rather than to just be itself. Physical processes alone (understood without teleology) are not inherently about things. The mind is always about things. Stated another way, physical processes (understood without teleology) have no purpose. Mental processes always have purpose. In fact, purpose (aboutness-intentionality-teleology) is what defines the mind. And we see the same purpose (aboutness-intentionality-teleology) in nature.
Intentionality is a form of teleology. Both intentionality and teleology are goal-directedness — intentionality is directedness in thought, and teleology is directedness in nature. Mind and teleology are both manifestations of purpose in nature. The mind is, within nature, the same kind of process that directs nature.
In this sense, eliminative materialism is necessary if a materialist is to maintain a non-teleological Darwinian metaphysical perspective. It is purpose that must be denied in order to deny design in nature. So the mind, as well as teleology, must be denied. Eliminative materialism is just Darwinian metaphysics carried to its logical end and applied to man. If there is no teleology, there is no intentionality, and there is no purpose in nature nor in man’s thoughts.
The link between intentionality and teleology, and the undeniability of teleology, is even more clear if we consider our inescapable belief that other people have minds. The inference that other people have minds based on their purposeful (intentional-teleological) behavior, which is obviously correct and is essential to living a sane life, can be applied to our understanding of nature as well. Just as we know that other people have purposes (intentionality), we know just as certainly that nature has purposes (teleology). In a sense, intelligent design is the recognition of the same purpose-teleology-intentionality in nature that we recognize in ourselves and others.
Teleology and intentionality are certainly the inferences to be drawn from the obvious purposeful arrangement of parts in nature, but I (as a loyal Thomist!) believe that teleology and intentionality are manifest in an even more fundamental way in nature. Any goal-directed natural change is teleological, even if purpose and arrangement of parts is not clearly manifest. The behavior of a single electron orbiting a proton is teleological, because the motion of the electron hews to specific ends (according to quantum mechanics). A pencil falling to the floor behaves teleologically (it does not fall up, or burst into flame, etc.). Purposeful arrangement of parts is teleology on an even more sophisticated scale, but teleology exists in even the most basic processes in nature. Physics is no less teleological than biology.
Although my own view on ID is more Thomist, that of course overlaps to some extent with other ID perspectives. Nearly all change in nature, in living and non-living things, is “designed,” in the sense of teleology. Physics is just as teleological as biology. In biology the teleology is more complex, but not any more teleological. An electron orbiting a proton manifests purpose no less than an organism manifests purpose. This is, I believe, a clear inference from Aristotelian-Thomistic metaphysics, and it’s the basis for the Fifth Way. Note that St. Thomas appeals to very simple processes — a directed arrow — to demonstrate teleology. He is not interested in complexity per se, and he makes no reference to the complexity of life. He uses even the simplest natural goal-directed change to demonstrate God’s agency.
Intentionality is the hallmark of the mind, just as teleology is the hallmark of nature. We, and the world in which we live, are shot through with purpose.