Various philosophers confused by German Idealism formed the idea that since nothing could truly be known, nothing could be proved to exist. The idea wasn't new; it had first been proposed by pre-Socratic Greek philosophers called Skeptics.

The immediate implications were more obvious than with previous incarnations, however—these German and French skeptics were of the opinion that since nothing could be proved to exist, nothing had meaning. Some Russians who got their hands on this theory called it nihilism, and Nihil gained a reputation as a hard-drinking immoralist from the North.

Some Frenchmen tried to give nihilism an intellectual edge and invented modern existentialism, writing huge books and weird novels designed to prove that nothing had meaning. In the end, brought to despair by their own theories, they were forced to either join radical political parties, become postmodern and admit that everything had meaning and all meanings were contradictory, or write books on literary criticism sure to be hailed as genius because no one could understand them.

Most people accept the nature of reality as self-evident. The average non-Christian is materialist by default, meaning for them reality is defined by and encompassed in the material (physical) world. Materialists believe everything—even thoughts and ideas—are composed of matter.

If philosophical ideas had opposites (or antitheses, as Hegel put it), idealism would be the opposite of materialism; according to idealists (of which Hegel was one), ultimate reality exists not in the material world but in the spiritual world of forms or ideals. The material world, for them, is made up of representations, mirror images of the ideals that exist fully elsewhere. Plato was essentially the first idealist, explaining his theories most clearly in his famous Allegory of the Cave.

Christian dualism states that reality is comprised of both material and spiritual aspects. The best example of the Christian understanding of reality is the doctrine of the Incarnation—Jesus was both fully God and fully man, the perfect marriage of spiritual and material essence in one person. We often assume everyone else sees the world similarly, which can lead to confusion in dialogue since materialists, idealists and Christians all use similar terminology.

The question of reality and its nature is one of the primary questions of philosophy. The technical term is "metaphysics" (meaning "transcending physics") because its concerns aren't addressed by any specific or natural science. God cannot be proved to exist using geology (much as some people try) nor can He be proved not to exist using astronomy (even though Sagan thought he could).

Metaphysics is the logical starting point for all philosophical endeavor. Modern philosophy has tried to distance itself from metaphysics; Christian thinkers are trying hard to bring it back.

Review by C. Hollis Crossman C. Hollis Crossman used to be a child. Now he is a husband and father, teaches adult Sunday school in his Presbyterian congregation, and likes weird stuff. He might be a mythical creature, but he's definitely not a centaur.Read more of his reviews here.