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.

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’s objection to analogy in design argument

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. Hume is pointing to how radically disanalogous the creation of the universe could be to anything else we know of:

“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·? Have worlds ever been formed under your eye; and have you had leisure to observe the whole progress of world-making, from the first appearance of order to its final consummation? If you have, then cite your experience, and deliver your theory.” – Hume

The creation of the universe is so far from our understanding. For all we know, it may be unlike the creation of anything within the universe (like the creation of houses or watches). So, we have no hope of claiming an analogy between the origin of anything in the universe and the origin of the universe itself.

Finally, Hume argues that we can’t even claim there is analogy between artefacts and natural objects. Artifacts are mechanical, meaning they have a mathematically precise design and structure. In general, however, the universe appears more organic. It is more chaotic.

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’s ‘commitee of Gods’ objection

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.

Evolution & the problem of evil

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 

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.

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.

F. R. Tennent’s design arguments

Tennent made two main arguments which paved the way that most defenders of the design argument went in after Darwin.

The strength of Tennent’s design arguments is that they cannot be countered by evolution but actually show that God must exist in order for evolution to be possible.

Tennent’s aesthetic principle suggests that evolution could not have produced humans without God’s interference with evolution. How can Darwinian evolution explain our perception of beauty? It doesn’t give us a survival advantage, yet it evolved. Only God controlling evolution can explain this.

The issue is, perception of beauty might serve some evolutionary function that we just don’t understand. Or it might be the biproduct of something which does provide survival, such as mate-attraction. It’s hard to really prove that our aesthetic sense has no relation to anything evolutionarily advantageous.

Tennent’s anthropic principle. Tennant points out that this universe being hospitable to living beings requires a “unique assembly of unique properties” on a “vast” scale, including “astronomical, thermal, chemical, and so on”. Our universe has to be orderly and the order must be of a particular kind in order for evolution to have been possible and thus for us to exist. This suggests that our planet has been specially designed for human life to be possible.

However, Tennant’s argument is now quite outdated in the face of our modern scientific knowledge. Although the conditions on earth are very precise, given how large the universe is and how many planets there are in it, we should expect there to be many earth like planets completely by chance. No special kind of explanation like design is necessary. In our galaxy alone there are 100 billion planets. Many other earth-like planets have actually been observed. Estimates put the number of earth-like planets in our galaxy at around 6 billion.

Swinburne’s anthropic fine-tuning design argument from temporal order (regularities of succession)

The strength of Aquinas’ approach, developed by Tennant & Swinburne, is the focus on temporal order.

 Paley’s problem was relying on spatial order (regularities of co-presence), which is the order of objects in space. The human eye is an example of spatial order because it involves the complex arrangement of things in physical space.

Spatial order cannot justify belief in God because it can be explained by evolution or Hume’s arguments that it could result from chance (spatial disorder, the epicurean hypothesis & problem of evil).

Swinburne was influenced by Aquinas’ 5^th way and Tennant’s anthropic principle which pointed to order in the way the universe works, not merely the complex spatial order of objects and their parts.

Temporal order (regularities of succession) refers to the orderliness of a thing’s behaviour over time due to physical laws.

E.g., the element of hydrogen has the same properties everywhere in the universe and since it first existed. The electron has a certain amount of negative charge and if it were different to less than a trillionth of a degree atoms could not exist. All of this orderliness persists throughout time which makes it temporal order.

Temporal order is maintained by natural laws – the laws discovered by physics.

“The proponent of the argument from design does much better to rely for his premiss more on regularities of succession. St Thomas Aquinas, wiser than the men of the eighteenth century, did just this” – Swinburne.

This raises questions about the explanation of these laws. We should not expect such order to exist by chance, nor could evolution explain them.

• Why are there laws of nature at all?
• Why are the laws of nature uniform and unchanging?
• Why do we have these laws, rather than other laws?
• Why are the laws that exist so perfect for human existence, when so many others are possible?

Number 3 is sometimes called ‘fine tuning’. If the laws of our universe, such as the charge of the election, were a tiny degree greater or lesser, atoms and thus humans could not exist at all.

Having established the need for an explanation, Swinburne rejects ‘chance’ and ‘science’ as potential explanations.

It is unimaginably unlikely for ‘chance’ to be the explanation for why a universe with our exact laws exists.

Science cannot explain why these laws exist. Science tells us the what but not the why. For example, science can tell us that E=mc², but it cannot tell us why E=mc². Science can discover the laws of nature but cannot tell us why there are laws or why there are these laws, so it cannot tell us why the laws are fine-tuned for life. Science cannot even explain why the universe can even be understood by science at all. The best explanation of the fine-tuning of the universe is God.

So, Swinburne argues we must turn to another sort of explanation. We know from experience that temporal regularities can be caused by persons. Human minds often impose temporal regularities through their choices, such as choosing to sleep at night. The explanation of those temporal regularities is that they were designed, i.e., intentionally created by an intelligent mind. Swinburne calls this a personal explanation.

The only available and therefore best explanation of the temporal regularities in nature is a personal explanation. Only God would have the power to have designed the laws of physics. So, God exists.

The issue of whether God is the best or only explanation

Hume’s Epicurean hypothesis. Epicurus was an ancient Greek philosopher who thought the universe was had existed infinitely and was composed of atoms. Hume pointed out that if Epicurus was correct, then a chaotic random universe, given an infinite amount of time, will by complete chance occasionally assemble itself into an orderly one. The atoms will happen to collide in such a way that an orderly arrangement of them will come about. On an infinite time scale, if something can possibly happen then no matter how low the probability, it becomes 100% guaranteed to happen.

For example if monkeys were randomly banging away on typewriters for an infinite amount of time, then they would produce the entire works of Shakespeare.

Similarly, a chaotic universe of randomly moving and fluctuating objects will happen to coalesce into an orderly arrangement given an infinite time frame.

The glaring issue for Hume’s point is that the current scientific evidence suggests the universe, at least our observable universe, began at the big bang some 13.8 billion years ago. It hasn’t had an infinity of time to organise by chance.

The evidence may be against infinite time existing, but there could still be infinite space in the form of the multiverse. The multiverse theory suggests our universe is just one of an infinite number of universes. Every single possible type and permutation of universe exists, including every possible set of physical laws. Some universes will be completely chaotic, others will be orderly. Physicist Max Tegmark suggests this defeats design arguments, including fine tuning versions like Swinburne’s.

If a multiverse exists, then every possible type of universe is certain to exist, including ours and others similar to ours. This gives us a scientific explanation of the spatial or temporal order we observe. 

Counter: No evidence for the multiverse theory

However, Swinburne responds there is very little evidence for the multiverse theory. Polkinghorne agrees and claims that the multiverse theory is a ‘bold speculation’, a ‘metaphysical guess’.

Hume’s ‘unique case’ attack on the design argument’s empirical validity

In this argument, Hume sets an empirical standard for justifiably inferring a designer from the universe and argues design arguments have not met it.

Hume contends that inferring the existence of a thing from the existence of another thing through induction requires experience of their constant conjunction. If we want to infer the existence of a designer from a thing, we need either:

1. Experience of that thing being made conjoined with its designer.
2. Experience of similar things being made and their designer.

Hume illustrates. Justifiably inferring that a house has a designer requires either experience of that house being made by a designer, or experience of other houses being made by a designer.

The issue is, we clearly do not have either such experience regarding the universe.

“But it is hard to see how this pattern of argument can be appropriate in our present case, where the objects we are considering don’t fall into sorts, but are single, individual, without parallel or specific resemblance.“ – Hume.

“To make this reasoning secure, we would need to have had experience of the origins of worlds” – Hume.

All we experience is one case, the universe itself. We do not experience the origin of the universe, nor a creator designing it. The universe is a unique case because nor do we experience the origin of other universes, let alone creators conjoined with them.

So, we ultimately have no basis on which to infer the existence of a creator from our universe. Hume concludes that the origin of the universe, “exceeds all human reason and enquiry.” The only rational thing to do is suspend judgement and admit that we do not know why the world exists as it does.

“A very small part of this great system, during a very short time, is very imperfectly discovered to us; and do we thence pronounce decisively concerning the origin of the whole?” – Hume.

Counter to Hume: design arguments as abductive

We could read design arguments as abductive – inferences to the best explanation, e.g. of:

• Natural laws (Aquinas & Swinburne)
• Complexity & purpose (Paley)

Swinburne especially seems to present the design argument in this form. He argues we lack a scientific explanation, and that in fact a scientific explanation is impossible. This justifies us in seeking a ‘personal explanation’ as that’s the best explanation we have.

Evaluation critiquing the design argument

However, Hume would object. We could grant Swinburne his premise (which physicists like Max Tegmark dispute) that a scientific explanation is impossible. Nonetheless, it does not follow that we are justified in seeking another explanation. Hume’s point is that there is a minimum standard of evidence required to infer a designer. If we don’t have a scientific explanation, we have no explanation.

Swinburne’s ‘personal’ explanation fails to meet Hume’s standard. When it comes to the cause of the universe, inference merely from causes we observe in the universe is inadequate. So, we should suspend judgement and accept that we do not know why the universe is the way it is.