Does Kalam lead to the Trinity?

The Kalam cosmological argument is short: whatever begins to exist has a cause; the universe began to exist; so the universe has a cause. It was developed by medieval Muslim theologians, including al-Ghazali, and made popular today by the Christian philosopher William Lane Craig, who argues that the cause must be uncaused, timeless, spaceless, immaterial, personal and one. Christians then identify this cause with the God of the Trinity: one God in three persons, Father, Son and Holy Spirit. The paper asks whether that step holds.

The authors start from the idea of a necessary being, one that cannot fail to exist, unlike contingent things that might never have existed. Kalam, they argue, points to a single necessary cause. Quoting Craig himself, they note that Christ's human nature is contingent: “there are possible worlds in which it never exists”. Christian teaching also holds that the Son is begotten of the Father and that the Spirit proceeds from the Father (and, in Western theology, from the Son), which suggests their existence is derived. A being with contingent or derived elements, the paper argues, cannot be wholly necessary.

Next they examine the two main ways philosophers explain the Trinity, drawing on the Stanford Encyclopedia of Philosophy. “One-self” models, associated with Karl Barth and Karl Rahner, treat Father, Son and Spirit as modes of one divine self; the authors argue this slides towards modalism, a view the early church rejected. “Three-self” or social models treat them as three centres of mind and will; the authors argue this yields three necessary beings, against Kalam's conclusion of one. Attempts to rescue this through “relative identity” they call controversial and arguably unintelligible.

Finally, the authors stress that the argument was first built to defend tawhid, the absolute oneness of God. Even Craig, they note, accepts that natural theology can establish only a general theism. They conclude that Kalam can show there is a necessary creator, but moving from there to the Trinity requires revelation and further premises, and that the argument fits the Islamic concept of God more naturally.