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Aquinas’ 5th way
Aquinas observed that natural objects/beings do not behave randomly, but moved towards a certain goal or purpose (end/telos).
We can observe that things act ‘always, or nearly always’ in the same way to ‘obtain the best result’, meaning to attain their purpose.
The idea is that things we observe in the world are goal-directed. For example, flowers can move in alignment with the sun throughout the day to get more sunlight. An acorn can grow into an oak tree. Water falls as rain and then evaporates as part of the water-cycle. The planets orbit the Sun. Everywhere we look, Aquinas wants us to notice that objects do not behave randomly but with regularity in a goal-directed way. This shows that it is not mere chance that objects behave in this way.
However, things in the world cannot have directed themselves towards their end. This is because they are either non-intelligent or insufficiently intelligent. Such things cannot move towards an end unless directed by a being which does have intelligence. A thing cannot reliably move with a purpose unless an intelligent being had that purpose in mind and directed its behaviour.
To illustrate this point, Aquinas draws our attention to the fact that we humans can direct an objects behaviour through exerting physical force on it, just as an archer does with an arrow.
An arrow hits a target even though it isn’t intelligent and cannot comprehend what it’s doing. There must be something which can comprehend the goal/end of the arrow and influenced/designed it to move in the way it does: the archer (who has intelligence) did this by shooting the arrow in a particular way while having the goal/end in mind.
God’s ability to direct the behaviour of things in the world is of a much greater type than our ability, however. God directs the behaviour of objects by creating natural laws which govern and regulate the behaviour of all objects by directing them towards the end that God has in mind for them.
Just as an archer has the power to make an arrow goal-directed, God has the power to make everything in the world goal-directed. So, there must be an archer for the arrow of the universe, which must be a God.
Aquinas’ Fifth Way:
P1: The behaviour of objects is goal-directed towards an end, because they follow natural laws.
P2: Natural laws cannot have been created by objects themselves, since they are non-intelligent or insufficiently intelligent.
C1: Natural laws must have an intelligent designer. ‘That thing we call God.’
William Paley’s design argument
Paley’s design qua Purpose is Paley’s argument that the combination of complexity and purpose, which we observe in natural objects/beings, is best explained by a designer.
Paley illustrates this with the example of a watch. If you were walking on a heath and came across a rock, you could easily think that it had always been lying there. At least, there is nothing about the rock which clearly suggests otherwise.
However, the situation is quite different if instead we came across a watch. There is something about a watch which suggests it had not always been lying there. It is composed of parts which are intricately formed so as to produce a motion which is so meticulously regulated as to point out the hour and minute of the day. It has complexity which is arranged so as to perform a purpose.
If the parts were themselves any differently shaped, composed of other materials, or were placed in any other arrangement, the purpose of telling the time would not have resulted. The watch could not have come about by chance nor been there forever because it has Complexity & Purpose. This must mean it had a designer – a watch maker.
Paley then points out there are also things in the universe that are complex and have a purpose. He points out in particular the complexity of the Human eye which is arranged to fulfil the purpose of enabling us to see. He also points to the wings of a bird and fins of a fish which are examples of complexity fitted together to perform a purpose of flying and swimming.
“Every manifestation of design, which existed in the watch, exists in the works of nature.” – Paley.
Since complexity and purpose in a watch tells us there must have been a watch maker, similarly, the complexity and purpose in the universe tells us that there must have been a universe designer. This designer must have a mind, because design requires a designer who has a purpose in mind and know how a certain arrangement of particular parts will bring about that purpose.
The use of analogy in design arguments
A crucial pillar and strength of design arguments is their use of analogy. Analogy provides a best explanation style argument. When we cannot directly observe the cause of something, it is empirically valid to turn to analogy. If we can explain something similar, it is reasonable to expect the unobservable but analogous thing to have an analogous explanation. This is how much of science operates. If a scientist wants to know how a drug will affect humans, they may test it on analogous creatures first.
Swinburne claims that arguments by analogy are “common in scientific inference”. If we know X is caused by Z, then we can reliably infer by analogy that something similar to X is caused by something similar to Z.
Weakness: Hume argues that it doesn’t follow from the similarity of two effects that they must have had similar causes. For example, the smoke produced by fire and dry ice is very similar, but their causes not similar. So, just because the effect of the universe and the effect of a man-made thing like a house (Hume’s example) or a watch (Paley) are like each other in that they both have complexity and purpose, it doesn’t follow that the cause of the universe must be like the cause of a house/watch i.e., a designer. Two effects which are alike (analogous) might in fact have very different causes.
Even if we could claim an analogy between natural things and man-made things, for all we know there may be no analogy between their origin. It is the universe’s origin/cause that matters to design arguments because they want to conclude it was a designing mind. Like effects can have totally different causes, so failing that, an argument from analogy could only work by finding something analogous to the creation of the universe itself. Yet, we are utterly ignorant about the state of nature during the beginning of the universe:
“Can you claim to show any such similarity between the structure of a house and the generation of a universe? Have you ever seen nature in a situation that resembles the first arrangement of the elements ·at the beginning of the universe·?” – Hume.
We don’t know what the origin of the universe was like, so we can’t know what it is analogous to.
Hume argues further that we can’t even claim there is analogy between artefacts and natural objects. Artifacts are mechanical, but the universe appears more organic.
Evaluation defending the design argument
Hume’s criticism is unsuccessful because Paley’s argument is arguably not based on an analogy. Modern philosophers often read Paley’s argument as not being based on an analogy between artefacts and the universe. His argument is that there is a property which requires a designer; the property of complexity and purpose – parts fitted together in a complex way to perform a purpose. When a complex of individually complex parts are fitted together in a meticulous way so as to achieve an overall function/purpose, it seems almost impossible for that to have come about by pure chance. A better explanation is a designing mind. Man-made things have this property but so too do natural things like the eye. Therefore, nature requires a designer because it has this property, not because of any analogy to man-made things. The watch is merely an illustration. We know the universe is designed because it has complexity and purpose.
Evaluation criticising the design argument
Hume’s argument is at least successful at criticizing analogical versions of the design argument, such as Aquinas’ and Swinburne’s.
Whether God is the best or only explanation
A strength of the design argument is its basis in Aquinas’ Natural theology. The advantage is that Aquinas carefully positioned his arguments to not claim too much. Paley adopts the same approach. They both accept that the design argument at most shows there is some designer of great power, but it doesn’t prove the Christian God in particular.
A. McGrath characterises Aquinas’ natural theology as showing an “a posteriori demonstration of the coherence of faith and observation” which shows the “inner consistency of belief in God”. The design argument shows that it is reasonable to believe in a designer. Christian belief is an case of belief in a designer, so Christian belief is reasonable. Aquinas claims this supported faith.
Weakness: Hume: God is not the only explanation. Hume argues that even if we had evidence of design in the universe, that would not support the claim that it was designed by the God of classical theism. It could have been made by a junior God, apprentice God – or even a God who died. There could be multiple designers – ‘a committee of Gods’. So, the design argument doesn’t even justify monotheism.
Evaluation defending the design argument
Swinburne claims that Hume’s points here are correct and that the design argument cannot prove that the designer has the attributes of the God of classical theism. Other arguments will be needed for that.
However, Swinburne thinks that Ockham’s razor can be used against some of Hume’s claims here. One God being responsible for the design of the universe is a simpler explanation than multiple. Swinburne also points to the uniformity of the laws of physics as suggesting a single designer.
Regardless, Hume’s critique doesn’t work against a posteriori arguments based in Aquinas’ style of natural theology (that Paley and Swinburne also adopt). They only seek to show that it is reasonable to believe in a designer. Hume’s insistence that we cannot know which type of designer there is does is irrelevant because that point is never denied by these proponents of the design argument.
Evaluation criticizing the design argument
The support and value for faith provided by an argument for some generic designer is very low.
There are an infinite number of Gods we could imagine.
A designer might not even be a God. It could be
Furthermore, simply showing the logical consistency of God with observation is insufficient. If that strengthens faith, then that shows that faith is irrational.
It’s not rational to believe something simply because it is consistent with observation. Actual evidence is required.
So, if the design argument was used to support belief in some generic God, that would be valid. However, it is not valid to use it to support belief in any particular God.
Darwin’s theory of evolution vs the design argument
A strength of the design argument is its reliance on purpose, which is difficult for an atheistic and scientific approach to account for and explain. Paley noted that mere complexity by itself could result from chance, but when combined with purpose it becomes more reasonable to infer design. Aquinas’ design argument also relies on purpose. We observe that entities act towards an end.
Weakness: Darwin’s theory of evolution by the process of natural selection showed that order in nature was not necessarily evidence of purpose and design but could instead be explained by natural scientific means. Proponents of the design argument are wrong to think that apparently purposeful features of animals must have been created by a designer.
Paley points out that cases where complexity serves a purpose are so unlikely to come about by chance that it is more reasonable to believe that they were designed. However, evolution shows that there is a third option.
There is genetic diversity within all species so that some members are better adapted to their environment than others. Natural selection refers to the increased chance for better adapted members of a species to survive and pass on their genes. The result is increased prevalence of adaptive traits over time. This explains how incredibly complex organisms can come to exist through the process of evolution by natural selection. It’s not an organism coming about by random chance, but nor does it require a designer. So, design arguments are wrong to think that the type of complexity we observe is suggestive of purpose, in which case it isn’t evidence of design.
Evolutionary biologist Richard Dawkins called his book where he criticised the design argument “The Blind Watchmaker”. This is a reference to Paley. Dawkins is accepting that yes there is a watchmaker of the universe, but it is blind, meaning the mechanical forces of nature.
Evolution shows how organisms can have goal-directed traits and behaviour without an intelligent mind designing them to have purpose. What Aquinas and Paley called purpose, modern science can explain to merely be the result of blind evolution.
Evaluation defending the design argument
Evolution is only a challenge to Paley’s design argument qua purpose.
Evolution may explain away the apparent purpose of biological organisms, but Aquinas’ 5th way applies to everything in nature, including the purposeful behavior of planets and stars. Evolution cannot explain that.
Swinburne develops Aquinas’ point, arguing that it is the laws of nature themselves which are evidence of design. Science can tell us what the laws are, but not why laws exist, nor why these laws exist. Especially when we consider that the laws are ‘fine-tuned’ for life, it begins to appear very likely that they were designed. Swinburne shows the limits of science at explaining purpose and the need to turn to a supernatural explanation.
Tennant’s design arguments not only get around the challenge of evolution but actually show that evolution actually requires God’s existence.
Evaluation criticizing the design argument
Even if evolution only directly targets Paley’s design argument, it still highlights a problem with design arguments in general.
Paley’s thought that the complexity and apparent purpose of organisms showed they had a designer. However, this turned out to be mistaken when science advanced and provided the better explanation of evolution.
So it looks like Paley’s mistake was that he identified the area of scientific ignorance in his time and assumed that God must be the explanation.
Technically speaking, this is also what all other versions of the design argument do as well.
Aquinas’ 5th way assumes that science will never explain goal-directedness of non-sentient objects.
Tennent assumes that science will never explain aesthetic perception nor the rate of life-requiring chemical and cosmological features of the earth.
Swinburne assumes that science will never explain why the laws of physics are the way they are.
All these thinkers identify the area of scientific ignorance in their time and then wrongly feel justified in asserting that God must be the explanation. We should just admit, with Hume, that we do not know why the universe is the way it is.
Design arguments & the problem of evil, inc. evolution
A strength of design arguments is that they are inductive and a posteriori. Philosophers like Hume & Russell and scientists like Dawkins doubt God’s existence for empirical reasons. They argue there is insufficient evidence to justify belief in God. Design arguments directly targets that position by attempting an inductive proof of God. They use a posteriori evidence as premises to inductively support the conclusion that God exists.
Weakness: Hume’s evidential problem of evil can be used against the design argument. The argument is that proponents of the design argument focus on the ‘good’ design but ignore the bad or evil design.
Hume aims to show that a posteriori observation of the world cannot provide a basis to conclude that a perfect God exists because the world contains imperfections like evil. The use of the problem of evil against the design argument tends to focus on cases of natural evil and animal suffering as informed by modern science and the theory of evolution.
Charles Darwin also made this point with examples:
“I cannot see … evidence of design … There seems to me too much misery in the world. I cannot persuade myself that a beneficent & omnipotent God would have designedly created the [parasitic digger wasp] with the express intention of their feeding within the living bodies of caterpillars, or that a cat should play with mice.” – Darwin
Darwin and Hume aren’t trying to show that there is no designer, just that a posteriori evidence cannot be used to show that the designer must be the God of classical theism (omniscient, omnibenevolent, omnipotent).
Hume puts the argument more philosophically:
P1. We are only justified in believing what the evidence suggests (empiricism).
P2. We only have evidence of imperfection (a world with both good and evil).
C1. We are only justified in believing that imperfection exists.
C2. So, belief in a perfectly good being is not justified.
Once we consider all of the a posteriori evidence, including natural evil, we see it cannot justify belief in a perfect God.
Evaluation defending the design argument
Paley responds that even a broken watch must have a watch maker, and so too must it be with the universe.
Alternative response to Hume’s evidential problem of evil: theodicies.
Evaluation criticizing the design argument
We can add contemporary evidence to Hume and Darwin’s point. We now know evolution of multicellular organisms has been occurring for at least 600 million years. This process involved an immense amount of suffering, both of animals and humans, who have existed for around 250 thousand years. This prompted C. Hitchens to argue that evolution itself is not just evidence that a perfect God didn’t create us, but is actually evidence there is no perfect God. After describing the details of suffering and extinction he sarcastically remarked “Some design, huh?”.
Possible exam questions for the Teleological argument
You could be asked to assess/evaluate:
- Whether a posteriori or a priori is the more persuasive style of argument.
- Whether teleological arguments can be defended against the challenge of ‘chance’.
- Whether or not there are logical fallacies in these arguments that cannot be overcome.
- Whether the teleological argument is successful, convincing, persuasive.
- Aquinas’ Fifth way.
- Paley
- Hume’s criticisms of the teleological argument
- The challenge of evolution.
Quick links
Year 12 philosophy topics:
Plato & Aristotle. Soul, Mind & Body.
Design/Teleological argument. Cosmological argument. Ontological argument.
Religious experience. Problem of evil.
Year 13 philosophy topics:
Nature & Attributes of God. Religious language. 20th Century philosophy of language.
OCR Ethics
OCR Christianity
OCR essay structure
OCR list of possible exam questions