Full notes A* summary notes This page: C/B summary notes
Aquinas’ 5th way
- Things we observe in the universe are goal-directed. E.g. flowers move towards the sun.
- Things are not intelligent, or not intelligent enough, to direct their own behaviour.
- This means there must be natural laws (laws of nature/physics) which govern the behaviour of things in the universe.
- Natural laws must have an origin – an intelligent designer.
- So, God exists.
- Analogy: archer and the arrow. If you see an arrow – it’s goal directed towards a target – you can know there must be an archer who shot it.
- Similarly, observing goal-directed behaviour of objects in the universe suggests there is a being which directed their behaviour through creating natural laws (God).
Paley’s design qua purpose (watch)
- Paley’s watch-maker argument: If you find a watch, you know it has a designer because of its complexity and purpose.
- It is made of smaller parts which are each complex and arranged in a complex and precise way in order to achieve an overall purpose – telling the time.
- We also find complexity and purpose in nature.
- Paley points out the human eye is the same – composed of small complex parts arranged in a complex precise way in order to achieve an overall purpose – sight.
- Complexity and purpose can’t come about by chance – there must have been a designer who intentionally arranged it with the purpose in mind.
- There are many cases like this in nature – the wings of a bird, the fins of a fish – all complex and purposeful.
- So, nature has a designer – it must be much greater and more powerful than any human designer – God.
Hume’s critique: evidential problem of evil
- We have evidence of evil in the world, so it’s not possible to infer the existence of a perfect God from the world.
- E.g. human suffering due to having frail bodies, animal suffering, most of the earth’s surface is too hot, cold or wet to live on. It doesn’t appear designed by a perfect God.
- Paley’s response: even a broken watch still has a designer.
- Soul-making theodicy attempts to explain the evil we see around us as something God allows so we can have soul-making (Hick’s development of Irenaeus’ theodicy).
Hume’s critique of analogy (Paley’s watch & Aquinas’ archer/arrow)
- Paley and Aquinas are trying to argue that because things in the world are like things humans create (watch) or do (goal-direct an arrow) – that therefore the cause of those natural things must be analogous too – must be an intelligent mind.
- But – things which are like each other can have very different causes – e.g. dry ice and fire produce very analogous effects (smoke) – but they are very different as causes.
- So, even if nature is like a watch or an arrow – that doesn’t mean the cause of nature is like the cause of a watch/arrow (i.e., an intelligent mind).
- Paley’s argument is not actually based on analogy.
- Paley isn’t saying that the universe is designed because it’s like the watch which is designed.
- Paley is saying that the universe is designed because it has complexity and purpose and the best explanation of that is a designing mind.
- The watch/arrow are just illustrations. The watch is just an illustration of how complexity and purpose comes from a designer. The arrow is just an illustration of how goal-directedness comes from a designer.
Hume’s critique: God not the only explanation (committee of Gods)
- Hume points out that even if the design argument worked – it would not prove a particular God – it could have been designed by a committee of Gods, a junior God, or even a God who then died.
Swinburne’s response & Aquinas/Paley’s natural theological approach
- Swinburne says one God is simpler than multiple (ockham’s razor – we should go with the simplest explanation that works).
- Swinburne accepts the design argument can’t prove the Christian God in particular – however, Aquinas and Paley also accept that.
- They aren’t trying to prove the Christian God in particular, they are only trying to show that it is rational and reasonable to believe in a God (Natural theology – intended to support faith rather than categorically prove the Christian God in particular).
- So the proponents of the design argument never claimed that it proved what Hume is accusing them of.
Evolution as a counter to the design argument
- explain how evolution works and how it explains the ‘appearance’ of design without recourse to a designer.
- Organisms might seem designed for survival in their environment, but really it adapted to its environment.
- Paley’s examples of natural complex & purposeful things were biological, like the human eye and the wings of a bird.
- However, Aquinas’ 5th way is about all natural bodies and phenomena. This would include the motion of the planets. That can’t be explained by evolution, since evolution only explains the appearance of biological organisms.
Tennant’s aesthetic principle as a response to evolution
- Aesthetic means beauty.
- Human beings have the ability to perceive beauty.
- Tennant points out that this could not have evolved by itself because it cannot give a survival advantage and therefore couldn’t be naturally selected for.
- So, God must have intentionally controlled evolution to add traits like aesthetic perception.
- Perhaps perception of beauty is essential to mate-selection – it allows animals to be attracted to each other (Dawkins’ response).
Optional Further Evaluation
- However – this response isn’t very satisfying – it’s hard to see things like appreciation of art and music as a by-product of sexual attraction – it seems totally different.
Tennant’s anthropic principle as a response to evolution
- Evolution wouldn’t even be possible without a planet with the right chemical composition and astronomical features (right distance from a sun, etc).
- So, a God must have designed this planet for evolution to even be possible.
- There are 10 hexillion planets in the universe – so we should expect a planet like earth to exist just purely by chance – it doesn’t need a special explanation like a God.
However – defence of anthropic argument
- Swinburne developed this anthropic argument – applying it to the laws of nature themselves (like Aquinas did) and pointed out that the laws of nature are fine-tuned for human existence to be possible.
- If the laws of nature were slightly different – we couldn’t’ exist.
- E.g. if the charge of the electron were any greater or lesser, to a tiny degree, atoms couldn’t exist and we couldn’t exist.
- So, there must be a God who designed the laws of nature themselves.
- Evolution clearly can’t explain the laws of nature/physics.