Imagine someone claiming we have a soul that is distinct from our bodies, and that this soul has weight when residing in the body. This testable hypothesis was actually put forth by a doctor named Duncan MacDougall. He revealed that, after death, human bodies became an average of 21 grams lighter. Had his finding held up in replicated studies, this would have been strong evidence for the existence of an independent spiritual soul that is not merely an emergent immaterial product of the body. Dr. MacDougall’s findings, however, did not survive scientific scrutiny, and few today think the soul has weight. However, many today still claim we possess a soul that is in some way not dependent upon our physical brains. Yet few offer descriptions of the soul that clearly differentiate it from neurological processes. If there were functions of the soul not dependent on the physical brain, that could be explored. If the soul can demonstrably persist in its observations or actions even after the brain structure cognitive scientists have assigned to those types of observations or actions has been injured or shut down, this would constitute strong evidence of something more than merely an immaterial manifestation of a physical process. This would strongly suggest the existence of a spiritual realm in which the dimension of spiritual causation was in play. However, that is not what we see. The more we explore and explain the functions of the brain, the less explanatory space there is for a spiritual soul as the cause of mental functions. In fact, there appears to be no function that does not directly emerge from a wholly physical neuronal process. Invoking a spiritual process on top of this wholly adequate physical explanation is superfluous.
One thing that does seem to offer support for a spiritual soul independent of the physical world is our subjective experience. We develop at a very early age a sense of soulish identity that is difficult to dismiss as illusory. Those born long before the soft tissue in brains was discovered to comprise 100 billion neurons can hardly be blamed for their certainty that there had to be some immaterial self that transcended the material world. However, during the development of science, several observations brought this quite intuitive notion into question.
- The larger the brain of an animal, the more the animal resembled humans in its behavior and social interactions. This depth of this sense of spirit seemed to be based on the size of the species’ brain.
- For every identifiable function of the human mind, some injury or lesion at a specific brain location could knock out that function. It appeared that the less functional the physical brain, the less detectable the alleged spirit.
- Philosophy explored the notion of immaterial entities such as economies and cultures and bee colonies that in clear ways transcended the behavior of their material constituents, yet remained entirely dependent on that material substrate. Immaterial systems emergent of, but wholly dependent on material constituents were recognized as common in our reality. A distinction between the definitions of the immaterial and the spiritual was established. (See “Supplementary M”.)
These observations have made the notion of a soul highly dubious.
As another example of the superfluous nature of a spiritual explanation piggybacking upon a wholly adequate physical explanation, consider how some flowers follow the arc of the sun throughout the day. Perhaps at one time it was reasonable to imagine a spiritual force as the cause of that magical alignment. Today, botanists have identified a physical mechanism behind that choreography between the flower and the sun. Those who suggest we impose on top of this physical explanation a spiritual explanation are adding an unparsimonious and superfluous explanation. And if there is no way to test whether, for example, a sun-worshiping soul resides in the flowering plant, all untestable spiritual, magical or supernatural entities such as invisible flower fairies become as equally likely as that sun-worshiping soul.
It is difficult for humans to shake the notion that we are somehow independent of our bodies. Even though most of us can not claim to have experienced a separation from our bodies, it is fun to imagine ourselves free of the physical and mortal constraints of the body in which we find ourselves. However, our imaginations are not very good indicators of what is true. Here, as in all inquiries, we much limit our degree of confidence in even delightful speculations to the degree of the actual relevant evidence.
There is also an odd argument heard from Christian leaders that, if there were no actual soul, we are simply a pile of biological tissue, and existential absurdity and despair would be the inevitable logical conclusions. Do animals without a human soul necessarily live a life of despair? Do they not possess the emotions that make life worth living? Would the fact that we are comprised of soulless tissue diminish or destroy the many positive emotions we feel? What actual meaning could ever exists apart from the meaning derived from our emotions and the values emergent of those emotions?
Behind the suggestion that we could not possibly be mere bundles of meat seems to be the hidden assumption that the bearer of the argument would find it unacceptable to discover that there is no ultimate objective meaning handed to them by some higher authority. Is this not a harmful bias that too often prevents an honest look at the evidence wherever it may lead?