Teleological arguments move from observations of purposiveness in the universe to the conclusion that God is the best explanation for the existence of the universe as it is. The Greek word TELOS originally referred to the target in archery and Aquinas, in his fifth way to God plays on this imagery by selecting an arrow as his analogy for purposiveness in the universe. He wrote…
“We see that things which lack intelligence, such as natural bodies, act for an end, and this is evident from their acting always, or nearly always, in the same way, so as to obtain the best result. Hence it is plain that not fortuitously, but designedly, do they achieve their end. Now whatever lacks intelligence cannot move towards an end, unless it be directed by some being endowed with knowledge and intelligence; as the arrow is shot to its mark by the archer. Therefore some intelligent being exists by whom all natural things are directed to their end; and this being we call God.”
The argument has its roots in Aristotle, who wrote of things in the universe and the universe as a whole advancing towards fulfilling a FINAL CAUSE, a telos or purpose, and suggested that there must be some mysterious force guiding this process and supporting the tendency towards fulfilment, goodness, in everything we see. It has been advanced many times and in many different variants since Aquinas, but it is characterised by arguing qua purpose and by the use of analogies to emphasise the improbability of efficient organisms and processes arising by chance. The classical teleological argument fell out of favour in the mid-19th century as Charles Darwin’s theory of evolution by natural selection was accepted as offering a natural explanation for the appearance of purposiveness in things. This essay will argue that while evolution remains the best reason for rejecting teleological arguments, there are other good reasons for rejecting them as well.
In 1779 David Hume’s Dialogues Concerning Natural Religion was published. It contained a complete, and eminently readable, refutation of the classical teleological as well as other arguments for the existence of God. Hume’s character Cleanthes sets up the argument, using the analogy of a machine and its maker(s)…
“Look round the world, contemplating the whole thing and every part of it; you’ll find that it is nothing but one big machine subdivided into an infinite number of smaller ones… The intricate fitting of means to ends throughout all nature is just like (though more wonderful than) the fitting of means to ends in things that have been produced by us”
“Since the effects resemble each other, we are led to infer by all the rules of analogy that the causes are also alike, and that the author of nature is somewhat similar to the mind of man, though he has much larger faculties to go with the grandeur of the work he has carried out.”
In 1803 Cleanthes’ argument was famously reproduced by William Paley, who used the analogy of a watch and watchmaker, concluding that from the similarity between the watch, natural organisms and even the universe as a whole…
The arguments presented by both Cleanthes and Paley are arguments from analogy and, as such, both can only be as strong as the analogies they employ. As Hume’s character Philo observed, Cleanthes (and reasonably Paley) relies on a “very weak analogy”. He reduces the argument to absurdity by suggesting alternative analogies – a house, legs, a ship – and concludes that
“Doesn’t the great disproportion ·between part and whole· bar all comparison and inference? From observing the growth of a hair, can we learn anything about how men come into being? Would the way a leaf blows—even if we knew this perfectly—teach us anything about how a tree grows?”
As Philo points out, there is a great dissimilarity between any analogy and the universe as a whole, and this is not just one of degree as Paley suggests in Chapter II Part V of Natural Theology. It is not reasonable, even from the perspective of the 19th Century Newtonian world-view, to suggest that
It follows that the analogies commonly employed to persuade readers by proponents of the classical teleological argument add nothing to the strength of their argument as a whole.
Apart from the analogies, the classical teleological argument can be summarised through this syllogism…
P1. Natural organisms act towards an end
P2. Natural organisms cannot act towards an end independently
C1. There must be some intelligence causing natural organisms to act towards an end
C2. This intelligence is what everybody calls God.
Clearly, both propositions can be disputed. There are many examples of inefficiency in nature and even where purposiveness is apparent, this can now be explained by evolution through natural selection. Yet the most problematic step in the argument is the secondary conclusion, that the “intelligence” is what everybody calls God. Surely God is usually seen to be whatever caused the universe to be the way that it is, however the qualities of omnipotence and omnibenevolence are usually imputed to God and there can be no doubt that the universe contains many examples of gratuitous innocent suffering. As Tennyson wrote “nature is red in tooth and claw” – Darwin himself and later John Stuart Mill remarked how implausible it is to suggest that a loving God could create a world in which animals must kill each other to survive. To many people this world seems more like the project of a sick science-fiction project than of the God of Christianity! Is it not reasonable to suggest that this universe could be the first, “rude effort of an infant deity”? This would better account for the imperfect characteristics of the universe as we find it than suggesting that it is the perfect product of a perfect God.
Further, there is nothing to suggest that the intelligent designer of the universe would have to be single. As Philo observed…
”a great number of men join in building a house or a ship, in rearing a city, in framing a commonwealth; why may not several deities combine in contriving and framing a world?”
This would render the secondary conclusion of the classical teleological argument, that the intelligence behind the universe could be called God, redundant. No Christian – and few members of other faiths – could accept that multiple Gods could have had a hand in creating the universe; to do so would place limits on the power of each, reducing the God’s to the status of spirits or demons. Philo admits that supposing the existence of multiple deities would be to “multiply causes unnecessarily” in a way that is philosophically unsound, and yet he argues that although it would be just as wrong to say that there must be one God as to say there must be multiple Gods. There is no way that human beings can know one way or the other. The secondary conclusion is not adequately supported by the premises and so the argument fails in its objective of being a demonstration of the existence of God.
Of course modern Intelligent Design arguments get around this difficulty by eliminating the secondary conclusion and leaving just the inference that God might be the intelligence that the argument has concluded to exist. Scholars such as Michael Behe and William Dembski point out the inadequacy of Darwin’s Theory of evolution through natural selection as a complete explanation for the universe.
Michael Behe points to irreducible complexity in microbiological organisms, such as the flagellum of certain bacteria, suggesting that linear evolution cannot account for complex organisms in which all parts need to work together for any function to be performed. Individual parts of irreducibly complex organisms are, Behe claims, without purpose unless all the other parts are present and correctly arranged. How could things evolve all at once to be this way? An intelligence is needed to explain these structures, some of which are the very building-blocks of life. It may be that evolution explains some aspects of nature, but without hypothesising intelligent design scientists cannot explain all of nature. Of course Behe’s argument is rejected by most mainstream scientists, who point out that parts of organisms can evolve out of existence as well as into existence. It could well be that each part of an irreducibly complex organism had a purpose in relation to the organism as it was in a previous stage of evolution, but as the new purpose evolved the old one became redundant and other parts of the structure with no new purpose did not survive. Most critics of Behe claim that he has either misunderstood the science and is making invalid claims to irreducible complexity or claim that he is too hasty in his conclusion that an intelligent designer hypothesis is required. If they are right, as I am persuaded that they are – the critics vastly outnumber and outrank his supporters – then Behe’s modern version of the teleological argument fails, even with its scientific examples and lack of secondary conclusion.
Like Behe, William Dembski proposes that an intelligent designer hypothesis is needed to account for the characteristics of natural organisms. Dembski appeals to what he calls “specified complexity”, instances where incredibly complex structures occur where each part of the whole is finely tuned for its job. The obvious example is DNA – each “letter” of a strand of DNA, ACGT, has a specific role and there are millions and millions of them in the most basic genome. As a statistician, Dembski calculates the probability of such specified complex structures arising by chance and concludes that where the probability surpasses what he calls the “universal probability bound” (10×1150) then it is incredible to suppose that it happened by chance rather than design. Dembski has as many critics as Behe. Again they claim that he has either misunderstood the science or jumped to his conclusion of intelligent design too hastily. Specifically, Dembski starts with specified complex structures as they are today and assumes that they were always meant to be this way when he calculates probability, which ignores the possibility that they genuinely exist by chance and could very well not exist or exist differently. Scientists are beginning to recognise that DNA contains a huge percentage of redundancy – code that was once relevant but which has been rendered redundant by new code which has been added as species evolve. Certainly, cutting out a section of DNA will change the efficacy of the whole strand, but that is because redundant elements are woven into the fabric of the whole. Take Brighton Pavilion as an example – its structure is highly complex and each bit is integral to the whole. This is not as a result of design but because the building was remodelled through several different designs and the present building incorporates and relies on elements of older buildings. The guttering runs inside the walls and now holds up the ceilings in some places. Start taking things away – even things as small as layers of wallpaper or light-fittings – and the whole building starts to crumble. As Richard Dawkins has observed, it is more reasonable to suggest that specified complex structures did arise naturally, over extended periods of time and as a result of environmental pressures, than to claim that they were created as they are my a mysterious “intelligence”. Such a conclusion multiplies improbabilities and by the scientific and philosophical principle of Occam’s Razor, is illogical. It follows that Dembski’s argument fails as well.
In conclusion it seems that the classical teleological argument fails to demonstrate the existence of God. The versions proposed by Aquinas, Cleanthes and William Paley are undermined by their use of weak analogies, their propositions are questionable and the conclusions, both that an intelligence and that God exists, are not adequately supported by those propositions. Most persuasively, the argument fails to explain how a recognisable God could create an imperfect universe or why the characteristics of the universe should not be imputed to demonstrate the existence of an imperfect God, or even a committee of Gods. Yet, in the end, Darwin’s theory of evolution through natural selection remains the best reason for rejecting teleological arguments, whether in their classical or modern forms. The failure of Intelligent Design arguments such as those proposed by Michael Behe and William Dembski shows that any attempt to argue qua purpose to God lacks credibility when evolution offers an elegant and demonstrable explanation of purposiveness that does not demand recourse to the supernatural. Certainly, examples of structures which biology does not yet understand exist. However absence of evidence does not constitute evidence of absence! Science is by its nature a process and it is unreasonable for religious critics to demand that it present a complete explanation now or admit failure. There is ample evidence that evolution continues to offer explanatory power and that it is making progress in explaining even the most irreducibly complex or specifically complex structures. Nevertheless, the failure of classical arguments qua purpose and modern derivations of them does not obviate the possibility of arguing to God qua regularity. In particular, the aesthetic argument presented by Richard Swinburne could survive the criticisms outlined here. That a universe should exist and evolve in the way that it does is incredible and this sense of awe and wonder could be the basis for a successful abductive argument for some sort of a God, if not the God of Classical Theism.
 Summa Theologica: First Part, Question 2, Article 3
 Dialogues Concerning Natural Religion (1779) Part II
 Natural Theology page 3.
 Dialogues Concerning Natural Religion (1779) Part II
 In Memoriam, Canto 56
 Dialogues Concerning Natural Religion (1779) Part V
 See “Darwin’s Black Box” (1994)
 In books such as “No Free Lunch” (2002)
 See the case he presents in episode 2 of his documentary “Religion: The root of all evil” (2002)
 The Existence of God (2004)