Traditionally, Christians have believed that human beings are composed of two parts: a material body and an immaterial soul. This is what is known as a dualist understanding of human nature. Recently, however, an increasing number of Christians have claimed that human beings are not composed of two distinct parts, but are made up of just one part: a material body. This is what is known as a monist understanding of human nature.
There are, of course, many references to people’s “souls” in Scripture, both Old and New Testaments. However, there are various ways of interpreting what these references mean. In most cases where Scripture refers to a person’s “soul” (Hebrew: nephesh, Greek: psyche), it is referring either to a person’s life/animating principle, or to a person’s inner life (emotions, feelings, etc.); it is not saying anything one way or the other about whether human beings have a distinct immaterial part of their nature that can be separated from their body. Thus, the many references to people’s “souls” in Scripture do not necessarily prove that human beings have souls in a dualist sense. So, we will need to dig a little deeper into the teachings of Scripture and Christian theology in order to answer the question of whether the dualist or monist understanding of human nature is correct.
Monism vs. Dualism
Many monists criticize the dualist understanding of human nature as a denigration of the importance of the body. If we believe that we are souls that are temporarily in bodies, they argue, then this will lead us to neglect the importance of our bodily needs and the bodily needs of others. If we believe we are just souls that are temporarily in bodies, then this will lead us to denigrate the importance of the physical world, including the important tasks of establishing justice in society and caring for the environment. Instead, we will end up narrowly focusing on the task of “saving souls.” This short-sighted, morally disastrous denigration of the importance of bodily life and the physical world, they argue, inevitably follows from the acceptance of a dualist understanding of human nature.
This moral critique of dualism may be a valid assessment of some forms of dualism; however, it is not a valid assessment of all forms of dualism. There are a variety of ways that a dualist can understand the relationship between the soul and the body. The two main kinds of dualism are Platonic dualism and Thomistic dualism.
Platonic dualism derives from the ancient Greek philosopher Plato. According to Plato, each person is a soul that happens to be (unfortunately) temporarily contained within a body. At death, our souls leave our bodies and go to the immaterial realm, which is a good thing, because our souls are then free from the limitations of the inferior physical world. Many early Church Fathers were influenced by Platonic philosophy, and, sometimes, their understandings of the relationship between the body and the soul were unduly influenced by Plato’s view.
Thomistic dualism derives from the Medieval Christian philosopher St. Thomas Aquinas, who largely based his understanding of the relationship between the body and the soul on the ancient Greek philosopher Aristotle. Aristotle believed that people were a combination of two parts, body and soul, and that, at death, the soul ceased to exist. Aquinas adopted Aristotle’s basic understanding of body and soul, but he modified it to make it consistent with Christian theological beliefs. For Aquinas, human nature is fundamentally a holistic union of both body and soul, but it is possible for the soul part of our nature to exist temporarily in an incomplete state without the body, which is what happens in between our deaths and the future resurrection.
When we examine what the Bible has to say about human nature, it is clear that Thomistic dualism lines up with what Scripture has to say much better than Platonic dualism does. The Bible does not teach that we are souls temporarily housed in bodies, and that the Christian hope is for our souls to leave our bodies and to go off to heaven. Instead, it teaches that we are embodied beings, and that the Christian hope is for a future bodily resurrection into a perfect, embodied life in God’s New Creation. The Bible does not denigrate the physical world or our physical bodies.
The monist moral critique of dualism is a valid critique of Platonic dualism. However, it is not a valid critique of Thomistic dualism. We can believe that we have immaterial souls, while at the same time believing that we are fundamentally physical, embodied beings. We can believe that we have immaterial souls without denigrating the importance of people’s bodily needs. We can believe that we have immaterial souls without neglecting the importance of establishing economic justice and caring for the environment.
As long as we steer clear of Platonic dualism, then, dualism is perfectly consistent with the teachings of scripture and with a morally responsible Christian attitude towards life. But are there strong theological reasons for adopting dualism rather than monism?
The Problem with Monism
A number of New Testament passages seem to suggest that human beings have souls that can exist after their deaths. “Do not be afraid of those who kill the body but cannot kill the soul,” says Jesus. “Rather, be afraid of the One who can destroy both soul and body in hell” (Matt 10:28). On another occasion, Jesus tells the story of the rich man and Lazarus, which describes the rich man consciously existing in Hades and Lazarus existing at Abraham’s side after their deaths but before the resurrection (Luke 16:19-31). In the book of Revelation, the souls of the martyrs are seen in heaven, crying out to God as they await His final judgment and their resurrection (Rev 6:9-11).
Even leaving aside these Scriptural passages, though, there is a strong theological argument that can be made for dualism.
What happens to us when we die and our bodies decay away? According to monists, we cease to exist. At the future resurrection, then, God is supposed to bring us back to life. But if we are nothing more than bodies, how can this brand new body be the exact same person we are now?
Certainly, God could make a new body that is an exact copy of my current body (qualitatively identical). But if I am just a body, then how can this brand new body actually be me (numerically identical)? What if God made five copies of this brand new body? Which one would be me? There would have to be something uniquely connecting my current body to one of these future resurrected bodies which would maintain the continuity of my personal identity and subjective, conscious experience across my existence as these two different bodies. You could call it something other than a “soul,” but, whatever language you want to use, in order for the Christian doctrine of the resurrection to make sense, there must be some immaterial aspect of human nature that continues to exist after bodily death and then enters into a new, embodied existence at the resurrection. Monism is thus theologically problematic.
Some monists criticize the dualist understanding of resurrection as being tantamount to reincarnation, rather than genuinely being a resurrection. However, Thomistic dualism can provide a way of thinking about resurrection that renders this criticism null and void. Aquinas (and Aristotle before him) conceived of the soul as the “form of the body”; it is the soul which forms the matter making up our bodies into a living, biological organism. We know that the actual particles of matter making up our body are constantly passing in and out of it, such that, every several years, every molecule in our bodies has been completely replaced. Yet, it remains the same body. When we die, body and soul are separated, but the soul retains the “form” of our body. At the resurrection, God then “refills” the form of our body, bringing our bodies back into existence. It may be brand new matter, but it is the same body, just as, during our earthly lives, we are the same body, despite continually replacing the matter that makes it up. Of course, in the resurrection both our bodies and our souls will be transformed and glorified, but they will be the same bodies and souls.
Though monists make good critiques of Platonic dualism, they fail to make any convincing arguments against Thomistic dualism. And monists run into serious theological problems when they try to make sense of the Christian doctrine of the resurrection. Thus, there is no good reason to abandon the traditional Christian theological belief that human beings are composed of two parts: a material body and an immaterial soul.