The cosmological argument is the argument that the existence of the world or universe is strong evidence for the existence of a God who created it. The existence of the universe, the argument claims, stands in need of explanation, and the only adequate explanation of its existence is that it was created by God.

Like most arguments for the existence of God, the cosmological argument exists in several forms; two are discussed here: the temporal, kalam cosmological argument (i.e. the first cause argument), and the modal argument from contingency. The main distinguishing feature between these two arguments is the way in which they evade an initial objection to the argument, introduced with a question: “Does God have a cause of his existence?” [Robin Le Poidevin, Arguing for Atheism, Routledge 1996, Chapter 1]

To explain this objection, and how the two forms of cosmological argument evade it, I‘ll use a simple, generic statement of the cosmological argument:

The Simple Cosmological Argument

(1) Everything that exists has a cause of its existence.
(2) The universe exists.
Therefore:
(3) The universe has a cause of its existence.
(4) If the universe has a cause of its existence, then that cause is God.
Therefore:
(5) God exists.

This argument is subject to a simple objection, introduced by asking, “Does God have a cause of his existence?”

If, on the one hand, God is thought to have a cause of his existence, then positing the existence of God in order to explain the existence of the universe doesn‘t get us anywhere. Without God there is one entity the existence of which we cannot explain, namely the universe; with God there is one entity the existence of which we cannot explain, namely God. Positing the existence of God, then, raises as many problems as it solves, and so the cosmological argument leaves us in no better position than it found us, with one entity the existence of which we cannot explain.

If, on the other hand, God is thought not to have a cause of his existence, i.e. if God is thought to be an uncaused being, then this too raises difficulties for the simple cosmological argument. For if God were an uncaused being then his existence would be a counterexample to premise (1), “Everything that exists has a cause of its existence.” If God exists but does not have a cause of his existence then premise (1) is false, in which case the simple cosmological argument is unsound. If premise (1) is false, i.e. if some things that exist do not have a cause, then the cosmological argument can be resisted on the ground that the universe itself might be such a thing. If God is claimed to exist uncaused, then, then the simple cosmological argument fails.

Each of the two forms of cosmological argument discussed here is more sophisticated than the simple cosmological argument presented above. Each draws a distinction between the type of entity that the universe is and the type of entity that God is, and in doing so gives a reason for thinking that though the existence of the universe stands in a need of explanation, the existence of God does not. Each therefore evades the objection outlined above.

The Kalam Cosmological Argument

In the case of the kalam cosmological argument, the distinction drawn between the universe and God is that the universe has a beginning in time. Everything that has a beginning in time, the kalam cosmological argument claims, has a cause of its existence. As the universe has a beginning in time, then, the argument concludes, the universe has a cause of its existence, and that cause is God.

The uncaused existence of God, who does not have a beginning in time, is consistent with the initial claim of this argument: “Everything that has a beginning in time has a cause.” God’s uncaused existence therefore does not give rise to the problem encountered in the discussion of the simple cosmological argument above.

The Argument from Contingency

In the case of the argument from contingency, the distinction drawn between the universe and God is that the existence of the universe is contingent, i.e. that the universe could have not existed. Everything that exists contingently, the argument from contingency claims, has a cause of its existence. As the universe is contingent, then, the universe has a cause of its existence, and that cause is God.

The uncaused existence of God, whose existence is not contingent but rather is necessary, is consistent with the initial claim of this argument: “Everything contingent has a cause.” Again, then, God’s uncaused existence does not give rise to the problem encountered in the discussion of the simple cosmological argument above.

Each of these two forms of the cosmological argument, then, evades the objection introduced above in a distinct way. The first does so by distinguishing between things that have a beginning in time and things that do not. The second does so by distinguishing between things that are contingent and things that are necessary. In each case it is argued that the universe is of the former kind, that God is of the latter kind, and that the principle that everything has a cause applies only to things of the former kind, and therefore not to God.