The philosophical case that God exists

William Lane Craig's contribution to apologetics is as much about method as about content, and the method is worth adopting whatever the topic.

State the argument in numbered premises. Then a critic cannot simply express displeasure — they must identify which premise is false and say why. That single discipline transforms most conversations from an exchange of impressions into an examination of reasons.

The kalām cosmological argument

Developed by medieval Islamic philosophers, revived by Craig in a 1979 monograph, and still actively debated in secular philosophy journals — which is unusual for an argument with apologetic use.

1. Whatever begins to exist has a cause. 2. The universe began to exist. 3. Therefore the universe has a cause.

Defending premise 1

Note the qualifier: begins to exist. This is not a special exemption bolted on to protect God; it has been in the argument since its medieval formulation, and it does real work.

Three supports:

It is metaphysically obvious. Something cannot come from nothing, because nothing has no properties and no potentialities. There is no it to do anything.

It is universally confirmed and never falsified. Every event we have ever observed has a cause. If things could pop into existence uncaused, the puzzle would be why it only ever happens to universes and never to bicycles.

All science assumes it. The scientific enterprise consists of looking for causes. A researcher who concluded "it just happened uncaused" would not be doing science.

Defending premise 2

This is where the twentieth century changed the landscape. For most of history the scientific consensus favoured an eternal universe; Christians argued for a beginning on theological grounds and were considered unscientific for it.

The scientific evidence:

• Hubble (1929) — the universe is expanding. Run it backwards and you converge on a beginning.
• The cosmic microwave background (1965) — the residual radiation of that beginning, and the observation that made the Big Bang model dominant.
• The second law of thermodynamics — the universe is running down toward equilibrium. An infinitely old universe would already have reached it.
• The Borde–Guth–Vilenkin theorem (2003) — any universe that has on average been expanding must have a past space-time boundary. Vilenkin's own summary is direct: cosmologists can no longer hide behind a past-eternal universe; they have to face the problem of a cosmic beginning.

The philosophical evidence:

An actually infinite past generates paradoxes. If an infinite number of days had to elapse before today, today would never arrive — you cannot traverse an actual infinite by successive addition.

What the conclusion gives you

Ask what a cause of space, time and matter must be like.

It caused space, so it is spaceless. It caused time, so it is timeless. It caused matter, so it is immaterial. It brought a universe into being, so it is enormously powerful.

And it must be personal. This is the step most often missed. If the cause were a set of impersonal, eternally present conditions, the effect would also be eternal — sufficient conditions eternally in place produce their effect eternally. The only way to get a temporal effect from an eternal cause is a will: an agent who acts.

Timeless, spaceless, immaterial, immensely powerful, personal. That is not yet the God of the Bible. It is a remarkably specific description to arrive at from cosmology.

The fine-tuning argument

1. The fine-tuning of the universe is due to necessity, chance or design. 2. It is not due to necessity or chance. 3. Therefore it is due to design.

The physical constants fall within extraordinarily narrow life-permitting ranges:

• The cosmological constant is fine-tuned to roughly one part in 10¹²⁰. A tiny increase and the universe expands too fast for galaxies to form; a tiny decrease and it recollapses.
• The strong nuclear force: a 2% change and either no hydrogen or no heavy elements.
• The initial entropy: Penrose put the odds at one in 10^(10^123).

Necessity would require showing the constants could not have been otherwise. No physical theory suggests this, and it is generally regarded as the weakest option.

Chance is the multiverse. Take it seriously — it is a genuine proposal by serious physicists. But note that it is unobservable in principle, that the generating mechanism would itself need fine-tuning, and that BGV suggests it too would require a beginning. It is a metaphysical postulate, adopted specifically to avoid a metaphysical conclusion.

Design remains. And this is not a gap argument: we are not saying science cannot explain it, therefore God. We are saying that the pattern — many independent parameters, narrow ranges, converging on a functional outcome — is the pattern we universally recognise elsewhere as intention.

The argument from contingency

Leibniz's version, and it avoids the debate about beginnings entirely.

1. Everything that exists has an explanation, either in the necessity of its own nature or in an external cause. 2. If the universe has an explanation, that explanation is God. 3. The universe exists. 4. Therefore the universe has an explanation. 5. Therefore that explanation is God.

The force is that it works even if the universe is eternal. An eternal universe would still be contingent — it could have been otherwise, or not existed at all — and contingent things require explanation.

Leibniz's question is the deepest one available: why is there something rather than nothing?

The only possible terminus is a being that exists necessarily, whose non-existence is impossible. Which is precisely what "I AM WHO I AM" (Exodus 3:14) claims.

Handling the standard objections

"Who made God?" The premise is whatever begins to exist has a cause. God, by definition, did not begin. This is not special pleading — the argument concludes to a necessary being precisely because contingent beings cannot explain themselves. Asking what caused an uncaused being is like asking what is north of the North Pole.

"You cannot prove it." Not in the mathematical sense. Almost nothing outside logic and mathematics can be. The operative standard everywhere else — in history, in law, in science — is inference to the best explanation, and that is the standard being applied.

"That is just a god of the gaps." No. A gap argument says: science cannot explain X, therefore God. These arguments run on what science has positively established — that the universe began, that the constants are what they are. If cosmology had shown a past-eternal universe, the kalām would fail. It is falsifiable in principle, which gap arguments are not.

"This only gets you a deist God." Concede it at once, and cheerfully. It gets you a timeless, spaceless, immaterial, personal, immensely powerful cause. It does not get you the Trinity or the cross.

That is why the case has two stages. Natural theology shows that a personal God plausibly exists — which removes the a priori objection that miracles are impossible. Then the historical evidence for the resurrection identifies which God.

Conceding the limits of stage one makes stage two more credible, not less. A person who overclaims on the first argument will not be believed on the second.

What the arguments are for

They do not save anyone. Paul is clear that "the natural person does not accept the things of the Spirit of God" (1 Corinthians 2:14), and no one has ever been argued into the kingdom.

What they do is remove the intellectual permission to dismiss the question. A great many people believe, in a general way, that belief in God is intellectually disreputable — something no thinking person still does. That belief is false, and demonstrating that it is false clears ground.

"For his invisible attributes, namely, his eternal power and divine nature, have been clearly perceived, ever since the creation of the world, in the things that have been made" (Romans 1:20).

Paul says the evidence is there in the made things. The arguments simply help someone look at it.