Philosophical dualism relates to one’s understanding of reality as a whole. This dualism says there are two distinct aspects to reality as a whole—the natural realm and the supernatural realm. It is to say that there is a realm that is transcendent to the natural realm. The dualism is, in effect, another word for theism. The word theism comes from the Greek word theos, meaning “God.” Theism is the worldview that affirms the existence of God. The truth or falsity of this type of dualism rises or falls with the case for the existence and nature of God.

Philosophical dualism allows for the reality of miracles, which is an important distinction to make in the task of Christian apologetics. Miracles, by definition, are an intrusion into the natural realm by the transcendent God. Once the truth of the existence of God is demonstrated, arguments utilizing miraculous events (for example, the fulfillment of prophecy, the resurrection of Christ) can be marshaled to demonstrate that Christianity is the only true theism. This two-stepped approach is characteristic of the classical approach to apologetics.

(Ed Hindson & Ergun Caner, General Eds., The Popular Encyclopedia of Apologetics: Surveying the Evidence for the Truth of Christianity, Eugene, Oregon: Harvest House Publishers, 2008, 182; Excerpt from Dualism: Four Categories, 1st Category: Philosophical Dualism by Richard G. Howe)