Four kinds of argument, and what apologetics is said to be for

Human history, the notes say, is full of theologians and philosophers who have tried to prove a divine existence. Some have been sure their own arguments succeeded; others say that no attempt of that kind has ever worked. The kinds named are the ontological argument, the teleological, the cosmological, and the moral.

Douglas Groothuis is said to try an ontological apologetic through presuppositionalism, fideism, Reformed epistemology, and evidentialism. William Lane Craig, called a classicist in this telling, defines apologetics as a field of Christian theology that seeks a rational answer to the truth-claims of the Christian faith. Groothuis (D. Groothuis) calls it a rational defense of the Christian worldview that is objective, true, rationally persuasive, and appealing both existentially and subjectively, and he adds that setting out the claims of Scripture clearly and systematically does not exclude a rational procedure.

The audience of apologetics, in this telling, is the non-Christian, who cares more whether an argument is rationally persuasive than about a doctrinal explanation based on Scripture itself. On that background Groothuis recommends accepting a rationally based apologetic as a preparatory stage of evangelism, one that can remove or weaken intellectual obstacles to accepting Christ as Lord. The greatest controversies among the finest minds, he is said to have thought, have been about the existence of God and the attributes of God. Such an inference, the notes add, does not require an empirical premise; it proceeds on rational concepts.

Anselm’s Proslogion, a painter’s image, and Gaunilo’s reply

The ontological proof comes to the fore, the notes say, through St. Anselm’s Proslogion. Anselm argues that God is a being that cannot not exist. The justification for the claim “God exists” is given in two parts: first, that no reason can be found for non-existence; second, that nothing is greater than God. The formula he uses to prove the proposition is “God = the greatest thing.” No year is attached to the Proslogion in the unique body, and none is invented here.

A painter, in an example the notes record, may have an image in mind and not yet have carried it out, and so is not said to recognize that the work already exists in reality. The question whether there is a standard for telling what exists only in imagination from what exists in reality is raised by a monk, Gaunilo. He does not take Anselm’s proof of God’s existence as a problem about reality; he reduces it to a problem of logic.

Anselm’s painter example, Gaunilo says, does not help the proof of existence, because that proof is not made through external, objective verification and inference. He refutes the argument, in this telling, by distinguishing what is understood from what can be thought.

Malcolm’s question, and Plantinga’s great-making properties

Norman Malcolm, a pupil of Wittgenstein, is then said to analyze Anselm’s and Gaunilo’s concepts more strictly and to carry the discussion further. He asks what the phrase “something thought greater” really implies: whether actual existence is already greater than existence in the understanding, or whether actual existence and existence in the understanding, taken together, are greater than existence in the understanding alone. Anselm’s claim, as the notes restate it, is that if a thing exists both in the understanding and in reality, it is greater than if it exists only in the understanding.

In this way, they write, the ontological problem in natural theology — how God exists — is turned, through Anselm, Gaunilo, and Malcolm, into a philosophical question about what God’s existence means.

Plantinga’s argument borrows Leibniz’s idea that God’s existence is possible. From that non-contradictory Leibnizian idea he is said to set out a schematized inference for a proof of God’s existence, and to call the relevant features “great-making properties.” He accepts Anselm’s suggestion that if “that than which nothing greater can be thought” existed only as a non-existent being, it would be greater if it existed in reality. He also, the notes say, speaks of talking about a maximal greatness, or a maximal standard, rather than only of a being that has the maximal standard in some world or another. The same Korean report, at fuller length, is on CampusDown.

Sources

1. Notes on the historical flow of the ontological argument, set against other named kinds — teleological, cosmological, and moral — and against a frame from Groothuis and Craig on apologetics.
2. St. Anselm’s Proslogion, the formula “God = the greatest thing,” the painter example, and Gaunilo’s distinction between what is understood and what can be thought, without invented years.
3. Norman Malcolm, a pupil of Wittgenstein; and Plantinga’s use of a Leibnizian possibility and of “great-making properties,” as the unique body spells them out.

Last updated: 14 November 2026