In western philosophy, the answers to “what is true?” or “what is real?” have fallen into three categories. Regrettably, the names for these categories each have different meanings in other contexts. Philosophers seeking to explain what is real tend to be materialists or idealists or realists.
Materialists, in this pursuit, are philosophers who say that only material things are real. In other words, something that cannot be detected and measured and described scientifically does not exist. God, then, does not exist. Angels and demons do not exist; fairies and jinn do not exist. Bigfoot and surviving Ivory-Billed Woodpeckers apparently do not exist, since material and scientific evidence for them is lacking and incomplete. The human mind or soul or spirit, as distinct from the body and its parts, does not exist. What we perceive as our mind or soul or spirit, according to a materialist, is entirely the result of mechanical, chemical, and electrical events within our bodies, especially in our brains.
Idealists, on the other hand, say that reality consists entirely of mind and thought, or of soul and spirit. The material world is an illusion. Dreams, hallucinations, and the tricks of illusionists can be offered as evidence that the material world is not real, since our senses that describe that world can be fooled. Paradoxes about the material world also reveal it to be an illusion. Ancient Greeks demonstrated that motion is impossible, since the fastest runner cannot beat a tortoise in a race if the tortoise is given a head start. By the time the runner reaches the tortoise’s starting line, the tortoise has gone a certain distance; by the time the runner reaches that point, the tortoise has again gone further. Our senses show us that the runner will pass the tortoise, but reason and logic seem to say that passing the moving tortoise is impossible. Reason and logic, therefore, support idealism, a world of ideas where material entities are results of those ideas and do not exist on their own. Goodness, beauty, quality, love: these things really exist. Their reality shapes the illusion which we often treat as the real world.
Dualists hold that material and ideal entities both exist; both are completely real. Science perceives and measures the material world but is incapable of evaluating the ideal world, the world of minds and spirits, the world of thought and feelings. Not every dualist believes in a god or gods; those that do believe generally attribute creation—the beginning and existence of material things—to the divine spiritual Being or beings. Most dualists describe each human being as compound, consisting of both body and mind, or body and spirit. As the material body can be dissected and seen to have various parts, so the ideal being can be sorted into mind, heart, will, soul, spirit, self, and perhaps other categories.
Most people who take time to think about what is real probably conclude that dualism represents the real world better than materialism or idealism. Many professional philosophers, however, have good reasons to opt for materialism or for idealism. Some are skeptical, for example, of the description of a human being as both material and spiritual—the philosophers refer to that model as the “ghost in a machine.” Other options have been considered—one ancient option which stands apart from these three traditional options, and other approaches that acknowledge duality in what is real but still consider either matter or mind/spirit to be the primary reality. J.