Cosmological arguments - AO1

What is the cosmological argument?

An a posteriori argument that argues from the existence of the universe (motion, causation, contingency, or beginning) to the existence of God as a necessary first cause.

What does a posteriori mean?

Knowledge based on experience or observation of the world, rather than logic alone.

What is a necessary being?

A being that must exist and cannot fail to exist; it does not depend on anything else for its existence.

What is a contingent being?

A being that depends on something else for its existence and could fail to exist.

What is infinite regress

An endless chain of causes with no first cause.

Who developed the classical cosmological argument?

Thomas Aquinas, in Summa Theologica, through his Three Ways (motion, causation, contingency).

Aquinas’ First Way (Motion)

Everything in motion is moved by something else. An infinite regress of movers is impossible, so there must be an unmoved mover, identified as God.

Aquinas’ Second Way (Causation)

Everything has an efficient cause. Nothing can cause itself. An infinite regress of causes is impossible, therefore there must be a first uncaused cause, God.

Aquinas’ Third Way (Contingency)

Contingent beings exist but could fail to exist. If everything were contingent, there could have been a time when nothing existed. Since something exists now, there must be a necessary being, God.

Why does Aquinas reject infinite regress?

Because without a first cause or mover, there would be no subsequent causes or motion occurring now.

What is the Kalam cosmological argument?

A modern cosmological argument arguing that the universe began to exist and therefore must have a cause beyond itself.

What does “Kalam” mean?

“Speech” or “theology” — referring to Islamic philosophical theology concerned with God’s nature and creation.

Kalam Argument – premise 1

Whatever begins to exist has a cause.

Kalam Argument – premise 2

The universe began to exist.

Kalam Argument – conclusion

Therefore, the universe has a cause, which is timeless, spaceless, and powerful — identified as God.

Al-Ghazali’s core claim about the universe

The universe began to exist, and anything that begins to exist must have a cause; therefore, the universe has a cause.

Why did Al-Ghazali reject an eternal universe?

He believed an actual infinite number of past events is impossible, so the universe must have had a beginning.

How does Al-Ghazali differ from Aquinas?

Al-Ghazali argues the universe began in time, whereas Aquinas believed the universe could be eternal but still dependent on God.

What is an actual infinite?

A completed infinite set (e.g. an infinite number of past events existing all at once).

What is a potential infinite?

An infinite process that is never completed (e.g. counting numbers).

Which type of infinity does Craig reject?

Actual infinity — he argues it cannot exist in reality.

What is Hilbert’s Hotel?

A thought experiment showing the absurdities of actual infinities: a hotel with infinitely many rooms can still accommodate more guests.

Why does Craig use Hilbert’s Hotel?

To show that actual infinities lead to logical absurdities and cannot exist in the real world.

How does Hilbert’s Hotel support Kalam?

If the past were infinite, it would involve an actual infinite number of events, which Craig argues is impossible — so the universe must have begun.

What does Craig mean by “the infinite cannot be traversed”?

You cannot reach the present moment if an infinite number of past events had to occur first.