The Cosmological Argument (AQA A-Level Religious Studies): Revision Notes

The Cosmological Argument

Introduction

The Cosmological Argument is one of the key philosophical arguments for God's existence. It attempts to prove that God exists by examining the nature of the universe itself. The argument is a posteriori, meaning it relies on observation and experience of the world around us, rather than pure logic alone.

For this topic, you need to understand six key areas:

• The basis of Aquinas' argument in observation
• Aquinas' Way 3: the argument from contingency and necessity
• Criticisms from Hume and Russell
• The strengths and weaknesses of the argument
• Whether the argument counts as a proof
• The value of the argument for religious faith

Aquinas presents his Cosmological Argument through three of his Five Ways in the Summa Theologica. Way 1 argues from motion and change, Way 2 from causation, and Way 3 from contingency and necessity. You only need to study Way 3, though understanding that all three arguments are related will help you grasp the overall approach.

The basis of Aquinas' argument in observation

Aquinas' third way begins with careful observation of the universe. When we look at the cosmos, we see an information stream stretching back nearly 14 billion years to the Big Bang. The Andromeda Galaxy, for instance, is about 2.5 million light years away, so when we observe it, we are actually seeing it as it was 2.5 million years ago. This demonstrates that observing the universe means examining a vast chain of causes and effects.

The biophysicist Werner Loewenstein describes the universe as crisscrossed with information arrows, some travelling for nearly 14 billion years from the Big Bang. These information streams have led to the formation of galaxies, stars, planets, moons and ultimately life itself. Everything we observe is part of this continuous chain.

Key observational features

Aquinas' argument is a posteriori and inductive, just like Paley's Design Argument. This means it is based on what we can observe through our senses. When you look at a cup of tea, you can verify its existence through sight, touch, taste, smell and hearing. The same principle applies to the universe: our senses confirm its existence and properties.

Consider these examples of contingency:

• Galaxies can collide with immeasurable consequences
• Stars can explode and create new stars from their debris
• All heavy elements, including those in your body, come from such explosions
• Metal rusts, even stainless steel
• All living things die and become compost for new life
• Since the first microsecond of the Big Bang, the universe has been in relentless expansion and change

Nothing stays the same. Everything is contingent, moved, changed and caused by something else.

From this observation of universal contingency, Aquinas concluded that something must exist necessarily. If everything we observe is contingent, then the cause of the universe appears to lie outside it. Nothing we observe can explain why contingent things exist at all. Therefore, the Cosmological Argument deduces that this external reason must itself be necessary, not contingent.

Aquinas' Way 3: the argument from contingency and necessity

Thomas Aquinas (1225-1274)

Thomas Aquinas was descended from Italian aristocracy and belonged to the Dominican religious order. He possessed an extraordinary intellect and is widely regarded as the greatest theologian and philosopher in the Catholic tradition. According to tradition, shortly before his death he had a religious experience after which he stopped writing, believing his previous scholarly works were mere straw compared to such an experience. He was canonised as a saint in 1323 CE.

The text of Aquinas' third way

In his third way, Aquinas uses the word 'being' to mean both beings (like human beings) and things. When he discusses things that are possible to be and not to be, he means contingent things.

Here is the argument as Aquinas presented it:

The argument in modern form

The argument can be set out more clearly in contemporary language:

P1: Everything can exist or not exist; everything in the natural world is contingent.

P2: If everything is contingent, then at some time there was nothing, because there must have been a time when nothing had begun to exist.

P3: If there was once nothing, then nothing could have come from nothing.

C1: Therefore something must exist necessarily, otherwise nothing would now exist, which is obviously false.

P4: Everything necessary must either be caused or uncaused.

P5: But the series of necessary beings cannot be infinite, or there would be no explanation of that series.

C2: Therefore, there must be some uncaused being which exists of its own necessity.

C3: And by this, we all understand God.

Explanation of the argument

The argument consists of two main parts.

In the first part (P1-P3), the core reasoning stems from P2: if everything is contingent, then at some time there was nothing. Aquinas claims that all contingent beings have a finite lifespan. There is no contingent being that is everlasting, so there must have been a time when nothing existed. If there was such a time, then nothing would now exist, because ex nihilo nihil fit (out of nothing nothing can come). This is obviously false, because vast numbers of contingent beings now exist.

C1 concludes that something must exist necessarily.

In the second part (P4-P5), Aquinas addresses the possibility that there might be an infinite series of caused necessary beings. This would be absurd because then there would be no ultimate cause of the series, and therefore no series at all.

C2 concludes that there must be an uncaused necessary being who brings into existence all caused necessary beings and all contingent beings.

C3 identifies this as God.

Caused versus uncaused necessary beings

Aquinas was thinking of angels and human souls as examples of caused necessary beings. He was also prepared to admit that the universe itself might be a caused necessary being, meaning that at its most basic level matter may exist necessarily. However, even caused necessary beings require an uncaused necessary being to cause their existence.

Criticisms from Hume and Russell

F.C. Copleston and Bertrand Russell

Bertrand Russell (1872-1970) was highly critical of Aquinas, dismissing him as someone possessing little true philosophic spirit who already knew the truth before philosophising because it is declared in Catholic faith. Russell's most famous critique comes from his 1948 radio debate with the Jesuit priest F.C. Copleston (1907-1994). During this debate, Russell was cordial towards Copleston, though his conviction that religion is harmful superstition remained evident throughout.

David Hume and Bertrand Russell offer very similar criticisms of the Cosmological Argument, which is unsurprising given that Russell's ideas often depend heavily on Hume's work.

Criticism 1: the fallacy of composition

A fallacy is a failure in reasoning which makes an argument invalid. The fallacy of composition is the fallacy of inferring that something is true of the whole from the fact that it is true of part of the whole, or of every part of the whole.

Russell provides his best-known example of this fallacy in the 1948 radio debate with Copleston. He says: "Every man who exists has a mother, and it seems to me your argument is that therefore the human race must have a mother, but obviously the human race hasn't a mother – that's a different logical sphere."

Russell aims this criticism particularly at Way 2 (the argument from causation), where Aquinas argues:

• From: Every single event in the universe has a cause
• To: The universe as a whole has a cause

Copleston claims Aquinas is right to argue this way, but Russell rejects it completely. He suggests there is no reason why we should not argue:

• From: Every single event in the universe has a cause
• To: The universe itself is uncaused

What Russell says about Way 2 applies equally to Way 3. In Way 3, Aquinas argues:

• From: Every thing in the universe is contingent
• To: The universe as a whole is contingent

Russell claims this commits the fallacy of composition, because we can equally claim:

1. Every thing in the universe is contingent
2. But the universe as a whole is necessary

Response to the fallacy of composition criticism

While Russell is correct that arguments from part to whole can commit the fallacy of composition, this does not apply to all such arguments. Consider these two arguments:

Bruce Reichenbach suggests that Way 3 resembles Argument 2, so is not fallacious. Compare their forms:

Argument 2:

• The wall is built from bricks
• So the wall is brick

Way 3:

• The universe is built from contingent things
• So the universe is contingent

On this reading, Way 3 does not commit the fallacy of composition. If the things that make up the universe can cease to exist, then the universe (which is no more and no less than the sum total of its parts) can also cease to exist. What can cease to exist requires an explanation beyond itself. An uncaused necessary being, beyond the universe, provides a good explanation for the existence of the contingent universe.

Criticism 2: rejection of necessary beings

Hume and Russell both reject the claim that any being can be necessary. Hume's version runs as follows:

• Any being that exists can also not exist
• There is no contradiction in thinking that any being does not exist
• This applies to God as well, because there is no contradiction in saying "God does not exist"
• So when Way 3 requires God to be a necessary being, this involves false logic

Hume assumes that when Aquinas argues God is a necessary being, he means God's existence is logically necessary. Hume has already rejected this claim in discussing the Ontological Argument, so he now insists that Aquinas is making the same mistake. Hume holds that all statements about existence are synthetic (based on sense experience), so they cannot be analytic (logically true).

Whereas we must think of $2 + 2$ being $4$ (because this is logically true), the mind never has to suppose that any object must remain in existence. Therefore, the words "necessary existence" have no meaning. Hume believes Way 3 makes the same mistake as the Ontological Argument.

To clarify Hume's point, consider these statements:

• Unicorns exist
• Peter Pan exists
• Hume exists
• You exist
• God exists

None of these statements can ever be analytic (logically true). We can only know they are true or false synthetically (by experience), if we happen to meet a unicorn, Peter Pan, Hume, you or God. All five statements are true or false depending on experience, including "God exists".

Response to Hume and Russell

When Aquinas discusses God as a necessary being in the Cosmological Argument, he is not talking about the logical necessity found in the Ontological Argument. In fact, Aquinas specifically rejects the Ontological Argument as a logical proof of God, so he can hardly be introducing it through the back door via the Cosmological Argument.

Metaphysical necessity is a form of necessity that derives from the nature or essence of things. Claims about metaphysical necessity are claims about the way things really are. For example, "Whatever is water is $\text{H}_2\text{O}$" seems to be a metaphysically necessary proposition, because whenever you find water it will be made up of molecules with one oxygen atom and two hydrogen atoms. That is the essence of water. It is what water really is.

Compare these two propositions:

1. All bachelors are unmarried males
2. Whatever is water is $\text{H}_2\text{O}$

Proposition 1 is logically true because we define bachelor as an unmarried male. It is true by definition.

Proposition 2 is not logically true. Rather, it is just part of the way things really are: water is always $\text{H}_2\text{O}$. So we can say that "Water is $\text{H}_2\text{O}$" has metaphysical necessity.

You should now see that whereas the Ontological Argument discusses God's logical necessity, Aquinas in the Cosmological Argument discusses God's metaphysical necessity. Aquinas claims that:

1. In our experience, everything is contingent
2. The existence of contingent things requires the existence of a being whose necessity is from itself and who causes the necessity in others. This is God.

Criticism 3: the universe as necessary being

Hume suggests that the material universe itself may be the necessarily-existent being. This would provide an adequate explanation without bringing God into it. It conforms with Occam's Razor, the principle that simpler explanations are better. It is simpler to work with one entity (matter) rather than two (mind and matter). If something must be necessary, why cannot that be the matter which makes up the universe? Why must it be an unobservable God?

Response to Hume

Aquinas had no problem with the idea that matter might exist necessarily (meaning that once created by God it is everlasting). However, for Aquinas, matter would be a caused necessary being (see P4 in Way 3), and would still need God as an uncaused necessary being to cause its existence (C2).

Criticism 4: the universe as brute fact

Russell suggests the simplest explanation of why the universe exists is that there is no explanation. The universe exists as an unexplainable brute fact (a fact with no explanation).

Response to Russell

Who is right: Aquinas or Hume?

The Cosmological Argument is inductive, so like all inductive arguments it is based on probability. It depends which you think is the most probable explanation for the universe:

1. A necessarily existent mind
2. Necessarily existent matter

Those who prefer option 1 are likely to believe that an all-powerful mind can explain the existence of matter better than matter can explain itself. They will say that (God's) mind creates matter.

Those who prefer option 2 will point out that matter has produced minds such as ours, so matter creates minds.

The strengths and weaknesses of Aquinas' argument

In the previous section we examined four alleged weaknesses of Aquinas' argument and concluded that the argument does not fail because of those objections. For those who accept the counter-arguments, these counter-arguments demonstrate the strengths of Aquinas' third way.

Summary of main criticisms and responses

Suggested weakness	Counter-argument
Russell: Way 3 commits the fallacy of composition	Not all such arguments are fallacious. Aquinas' argument resembles the "brick and brick wall" type that is not fallacious and might be right
Hume and Russell: We cannot show that any being's existence is logically necessary	Way 3 does not discuss God's logical necessity (that would be the Ontological Argument). Way 3 discusses God's metaphysical necessity, which is a powerful argument
Hume: The universe itself may be the necessary being	The case for necessarily-existing matter is no stronger than the case for a necessarily-existing mind
Russell: The universe exists as an unexplainable brute fact	Science assumes there are no brute facts, otherwise science would not work. If things in the universe are not brute facts, why should the universe as a whole be a brute fact?

Further areas of discussion

Weakness 5: Why should there be just one necessary being? Why could there not be a group of necessary beings?

Response: Aquinas admits there could be any number of caused necessary beings, but unless we admit the existence of an uncaused necessary being, there is no explanation for the existence of caused necessary beings. Aquinas allows for the possibility that, once created, the universe itself is a caused necessary being, along with angels and human souls. All caused necessary beings are given their necessity, so the giver of that necessity must contain the reason for its own existence. God is his own existence. To try to go back further than existence itself would be absurd.

Weakness 6: Why could there not be a group of uncaused necessary beings?

Response: A clear answer comes from Occam's Razor: one uncaused necessary being makes the fewest assumptions and does not multiply entities unnecessarily.

Weakness 7: Why can there not be an infinite regress of contingent beings, without any need for a first necessary being?

Response 7a: This would still not explain why there is something rather than nothing. Where we look for explanations of things in the universe, we generally find them, or expect to find them as science progresses. This implies that the universe does have an explanation for its existence.

Response 7b: Although we can understand the idea of an infinite past sequence in mathematics (e.g. $-1, -2, -3, -4, -5$, etc. to infinity), we have no evidence that an infinite past sequence can exist in the real world.

Weakness 8: Some current cosmological theories suggest that the universe may exist eternally and uncaused, without the need for a necessary being. For example, some theories explain the universe in terms of an infinite cycle of expansions and contractions (Big Bangs and Big Crunches).

The status of Aquinas' argument as a proof

Inductive arguments and proof

The third way is one part of an inductive argument for the existence of God. As we have seen with the Design Argument, inductive arguments deal in probabilities rather than proofs.

For most philosophers today, proof would need to be a priori, like the Ontological Argument. However, in most people's opinion, the Ontological Argument is a failed proof.

Alternative understanding of proof

There are reasons why we should accept a different idea of proof, namely proof based on overwhelming probability.

In a 2005 article focusing largely on the Cosmological Argument, Gerry J. Hughes argues that as well as the proofs we use in logic and mathematics, we do accept other kinds of proof based on what we can reasonably conclude about the real world.

We have no direct observational evidence that quarks exist, since no one has seen an isolated quark, yet the indirect evidence for their existence is so overwhelming that it can be considered a proof. The Standard Model of particle physics does not make sense without quarks, so they must exist in some manner.

We have what amounts to sufficient proof of the existence of unobservable entities (quarks) that it would be unreasonable to deny. The implications for the Cosmological Argument are obvious: God is an unobservable entity concerning whose existence it would be unreasonable to deny.

Hughes' four components of the Cosmological Argument

Hughes reduces the structure of the Cosmological Argument to four components:

1. Nothing happens without some causal explanation
2. A satisfactory explanation cannot appeal to something which just happened and was not caused (it cannot appeal to brute facts)
3. The existence of the universe requires an explanation outside itself
4. It is reasonable to think of this transcendent explanation as God

At this point, Hughes invokes Aquinas' third way:

The chain of explanations will be complete and satisfying only if in the end one reaches something which has not just happened, simply come into existence. In short, the chain will end when it reaches something which cannot not exist, that is to say, exists necessarily. The explanation will stop when one gets to a Necessary Being.

Hughes claims the argument is a proof as far as he is concerned, because the chain of reasoning means that no explanation will satisfy him apart from the existence of a necessary being. He admits he could not claim that somebody who disagreed with him was being unreasonable. Moreover, there would still be much work to do to identify the necessary being with the God of Jewish, Christian and Muslim tradition.

Limitations of proof status

Whatever conclusions you reach concerning Hughes' argument, the third way does not convince atheists, so it can hardly be a proof of God's existence that satisfies even the majority.

Hare's concept of bliks

R.M. Hare's concept of bliks is often brought up to settle arguments, though the usual result is to show that the argument cannot be resolved at all. According to Hare (following Hume), a blik is a view of the world, and our blik governs what is, and what is not, an explanation.

Moreover:

• Differences between bliks about the world cannot be settled by observation of what happens in the world
• No proof could be given to make us adopt one blik rather than another

Value for believers

For believers today, Aquinas' third way could give the support of reason and philosophy to what they already believe through faith. For someone convinced by faith that God exists, the third way supports this by offering a reasoned proof that God must exist as a necessary being.

The value of Aquinas' argument for religious faith

Reason supports faith

Some argue that Aquinas' third way has value for religious faith because, as part of his Cosmological Argument, it shows faith to be reasonable. The Cosmological Argument is a reasonable hypothesis that the universe owes its existence and nature to an uncaused necessary being. There are alternative explanations concerning the origin of the universe, but they have no more probability than the Cosmological Argument.

Accessibility to believers

Those with religious faith can easily understand the evidence used by the third way, which is based on what we can observe. With the Cosmological Argument generally, we observe that the universe is in constant motion and change and that events have causes. For the third way particularly, everything we see in the universe is contingent. Although Aquinas' arguments contain some difficult language, the concepts themselves, particularly that of God as a necessary being, are simple and can be understood by any believer.

Not all believers accept the argument

Not all those with faith in God accept Aquinas' argument. They might consider the argument flawed in one or more ways. For example, Kant believed in God (although the nature of that belief evolved considerably as he aged), but rejected the Ontological Argument. He also argued that the idea of God as a necessary being, as in the third way, depends on the Ontological Argument. Therefore, he argued that if the Ontological Argument fails, then the Cosmological Argument must fail too.

Equally, Karl Barth rejected any attempts to prove God's existence, believing that God can be known only through Jesus Christ, as revealed in scripture.

Faith supported by reason versus faith through grace

Aquinas held that knowledge of God comes from natural theology (what we can know by reason and observation) and by revelation (which we receive through scripture). Revelation is necessary because we could never reason our way to doctrines like the Trinity and the virgin birth of Jesus. God grants people the light of faith to understand these doctrines, whereas natural theology needs only human intelligence.

God of philosophy versus God of faith

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