William Lane Craig on The Kalam cosmological argument

No living thinker is more closely identified with a single argument than William Lane Craig is with the Kalam cosmological argument. He revived it from medieval Islamic philosophy in his 1979 doctoral thesis and has spent over four decades refining, defending, and debating it in academic and public settings.

The argument is deceptively simple: (1) Everything that begins to exist has a cause. (2) The universe began to exist. (3) Therefore, the universe has a cause. Craig defends each premise with a combination of philosophical argument and scientific evidence — particularly the Big Bang and the impossibility of an actual infinite series of past events. He then argues that the cause must be timeless, spaceless, immaterial, and enormously powerful — which, he contends, sounds a lot like God.

Craig's presentation of the Kalam is notable for its clarity and debating discipline. He typically structures his case as a formal syllogism, forcing opponents to identify exactly which premise they reject and why. This approach has made him one of the most effective debaters in the philosophy of religion, winning respect even from atheist philosophers who disagree with his conclusions.

Critics — including Dawkins, Krauss, and Carroll — challenge both premises. Some argue that quantum mechanics shows things can begin to exist without causes. Others argue that 'the universe began to exist' conflates a beginning of time with a beginning in time. Craig has detailed responses to each objection, making the Kalam perhaps the most thoroughly debated argument in contemporary philosophy of religion.