Galileo, Darwin, and Hawking: chapter 6

In this helpful chapter on ‘Big bang cosmology and God’ Dowe looks at the kalam cosmological argument, big bang cosmology, the anthropic principle and the many world’s explanation.

The kalam (literally ‘speech’) argument was largely developed by Abu Hamid Al-Ghazali (1058-1111). It looks something like this:

1. Everything that begins to exist has a cause of its existence.

2. The universe began to exist.

3. Therefore the universe has a cause of its existence. That cause we may call ‘God’. (p. 144)

Statement 1 was taken to be self-evident; statement 2 was defended on the grounds that there cannot be an infinite sequence of temporal events. That the universe had a beginning in time fitted well with Genesis and the Qu’ran.

However, if the universe is infinitely old then the kalam argument is flawed. The mid-twentieth century many cosmologists favoured an infinite steady-state model of the universe. Though towards the end of that century there was mounting evidence for the big bang theory – though some like Fred Hoyle (1915-2001) opposed it on metaphysical grounds.

The big bang model is now the scientific consensus. William Lane Craig has used the big bang to resuscitate the kalam argument. Stephen Hawking in his A Brief History of Time offers a no-boundary proposal to get around the idea that something outside the universe is needed to start things off. Dowe makes the wry observation:

…one gets the impression that the whole rationale for the no-boundary model is to avoid the conclusion that there is a God. (p 147)

Dowe then moves on to look at the anthropic—human-centred—principle (AP). He does so in a clear and useful way. He defines AP thus:

The term ‘anthropic principle’ refers to the remarkable connection between the initial conditions and constants of the universe, and the fact that life has arisen in the universe. (p. 148)

He then goes on to describe three possible responses as to why our universe is apparently fine-tuned for life: intelligent design, pantheism and multiple universes.

It was the atheist Hoyle who first used anthropic reasoning to explain how enough carbon was produce in stars to sustain human life. John Barrow and Frank Tipler’s The Anthropic Cosmological Principle did much to popularise the idea.

There are numerous forms of the principle: weak, strong, participatory final (or WAP, SAP, PAP and FAP; Martin Gardener has even suggested CRAP – completely ridiculous anthropic principle). All but the first are highly controversial.

Does the anthropic principle explain all the remarkable occurrences? SAP – the universe must have the properties that allow life to develop – and FAP – intelligent life must come into existence – need no further explanation. But why should we accept them in the beginning?

The AP is an argument to the best explanation – our existence (US) explains fine-tuning (F).

P(F) = negligible

P(F|US) = 1

therefore P(F|US) >> P(F)

But what is wrong with this reasoning? It uses the future to explain the past – a latter event is used to explain earlier events.

Retrodiction – predicting states of affairs that must have occurred given the present state – is acceptable though. We are here now, implies that the universe must be fine-tuned (as in WAP). SAP, FAP and PAP offer an explanation but not prediction.

The next question Dowe goes on to examine is: Is a theistic or pantheistic God an explanation of the AP? He suggests that the way God is used as an explanation is a version of the design argument. One objection is that this is open to the ‘god of the gaps’ problem as it may be superseded by scientific development.

Pantheism doesn’t offer a familiar model of explanation – it retains the word God, but removes any personal aspect to God, so it is not clear how this god could explain fine-tuning.

One argument that might provide an alternative to the design argument is that there is nothing to explain – the universe is a brute fact. Another is the multi-universe or worlds hypothesis, M.

In M there are a large finite number of universes – hence the chance that one is fine-tuned for life is very high. Other versions include Wheeler worlds (Mw) and Carter worlds (Mc). Mws are connected like sausages but are independent; Mcs are a string of infinitely many worlds where every possibility is substantiated.

Dowe then looks at Ian Hacking’s objection to M – they commit the inverse gambler’s fallacy (IGF). The gambler’s fallacy is that she reasons that we have been unlucky so far, so next time we will be lucky. If two dice has been thrown 35 times without getting a double six then she would be willing to bet that the next throw a double six would come up. The inverse gambler’s fallacy is to reason that good luck must have been preceded by bad luck. If she saw someone throw a double six, she would infer that the thrower must have thrown the dice many times before the double six was thrown.

An illustration shows how this relates to the multi-universe idea. There is a casino with an infinite number of rooms and in all the rooms coins are being flipped. The chance that someone has ten heads all in a row is high. This would be an example of the IGF – it is fallacious to think the chance that I’m in a room where ten heads are flipped in a row is greater given the multi-room theory.

Hacking maintains that M and Mw commit the IGF and he thinks that Mc might escape the IGF; however, Dowe does not.

The argument is not that some world is fine-tuned but rather this world is fine-tuned.

Does this mean that the existence of the universe needs no explanation? How do we decide which improbable events require explanation? Dowe’s concluding comment is apt:

There is something unsatisfactory about putting a world like ours down to chance. According to this view there is something special about our universe that sets it apart from other universes. Design explains this. (p.169)