The concept of the soul is at the heart of many schools of philosophy and many religions. It is believed to be the immaterial part of an individual, where personality and thoughts originate. According to Christianity, Islam, and a few other faiths, the soul will survive the body after death, and will face either an eternity of bliss or an eternity of agonizing torture, depending on what the person believed while they were alive on Earth. A 2008 poll conducted among 2,126 American adults found that 68% believe the soul continues to exist after death [1]. What makes us so sure that we have souls, and how are they really all that different from our physical selves?

I. Evidence of the Soul?

In 1907, the American physician Duncan McDougall weighed six patients who were in the process of dying from tuberculosis, and noted that each patient lost 3/4 of an ounce after the event of their death. Next, McDougall weighed 15 dogs and observed that no weight was lost when the animals died. The physician's conclusion was that the loss in weight of the human patients was a result of their souls leaving their bodies. Had Dr. McDougall actually weighed the human soul and discovered evidence for its existence? Not quite.

The sample size in the experiment was far too small, the methodology used was not consistent or precise, and as McDougall's contemporary Augustus P. Clarke pointed out, the study failed to consider the sudden rise in body temperature which occurs at death when blood is no longer air-cooled from circulation through the lungs. Clarke also noted that the rise in body temperature would cause sweat and moisture evaporation in human beings, explaining why they might lose weight while the dogs would not (dogs do not sweat, instead they pant). Even if McDougall's test had been more reliable, a loss in weight at the time of death in no way implies the existence or departure of a soul.

As ludicrous as the experiment may sound now, many people today believe that there is still other evidence of the soul that is found in near-death experiences (NDEs). A NDE occurs when an individual loses consciousness or momentarily dies and has a religious or spiritual experience of the afterlife, an encounter with an angel, or some other kind of metaphysical phenomenon. The interesting thing about NDEs is that all of them seem to be triggered by some immediate trauma. Pilots undergoing flight training in g-force test chambers have blacked out and had their own NDEs. Dr. Rick Strassman has suggested that during or following traumatic events, the brain may release massive quantities of Dimethyltryptamine, which will induce hallucinations.

NDEs are taken very seriously by those who experience them. I have no doubt that their experiences impacted them in deeply emotional ways. Having an "out of body" incident is understandably compelling evidence to a person that they have a soul. Yet it is always important to remember how easily our minds can be deceived. Lucid dreams may also seem incredibly real to us, but we know they are not accurate portrayals of events, persons, or reality. There is no good reason for believing that the soul (if it does exist) will manifest itself in our physical world, and in fact, that view is a minority view among those who tend to believe.

II. Closing the Gaps

Most religious believers will probably agree that since the soul is immaterial, it is not something which can be found by rational, verifiable, or scientific means. It is of a spiritual nature, not a physical one, they say. Just as many people have suited God to fill in the gaps of our understanding that science has not yet filled, the soul is proposed as the source of our intimate identity, the part of us that science cannot fully account for. Being that the soul is apparently such an elusive thing, it does seem fruitless to search for it by any testable or scientific method. However, as we are learning more about the function of our brains, the definition of the soul is sinking more and more into obscurity.

Neuroscientists have been able to observe and predict thought patterns as electrical brain signals flash across MRI screens, and some have even been able to induce religious experiences in patients [2]. Thoughts may not be tangible things, but there seems to be good evidence that they are connected to our physical brains and do not reside exclusively in an immaterial 'soul'. Decades of study in fields of anthropology, psychology, and sociology have all told us that our personalities are shaped by external factors like family, friends, environment, and so forth. Individuals who suffer some trauma to the brain will often lose aspects of their personality or memory, and it may impact the way they think as well.

One of the last great mysteries of biology and neurology is consciousness, and this is where much of the debate on mind, body, and soul focuses today. Science is far from having all the answers on consciousness, but several assumptions are made when one suggests that it is an attribute of the soul. There is no reliable evidence of a spiritual realm, and simply stating that something is non-physical does not automatically confer a spiritual nature to it. Even saying that something like consciousness is non-physical implies that it can exist without a brain to operate from. This seems like claiming that a computer program can operate without the hardware it runs on.

Consciousness, personality, and thought are all phenomena that show signs of natural evolution. Brain trauma can affect all of these in a person, and scientists have probed the brain in interesting ways to stimulate thoughts, feelings, memories, emotions, and other responses. There is good reason for concluding that these things are part of our physical reality and are inextricably tied to our brains. There are also lesser forms of each phenomena found in different animals, like chimpanzees, dolphins, and elephants. Every evolutionary development toward a heightened sense of consciousness or thought will produce a greater ability in rational thinking and problem solving, allow more interaction with other creatures, and would thereby increase the odds of survival. What reason is there to suspect that any of these phenomena are non-physical indicators of a soul?

Your soul is showing, but it's not the ambiguous New Age metaphysical thing you might think it is. From all current estimations, the soul is merely a conglomeration of traits, characteristics, and processes which can be reasonably considered all natural and physical. Yet we already have words and understanding of these concepts, so why add an extraneous label like 'soul' to them? Until a new, clear definition is given or until it is demonstrated that science cannot possibly explain certain elements in natural terms, assuming that the soul exists is exclusively an exercise of blind faith.

III. When the Soul Becomes Dangerous

As we have seen, the concept of the soul is extremely nebulous and subjective. The phenomena proposed as evidence of the soul also appear to be fairly grounded in our physical reality, leaving little reason to assume that areas we don't yet understand must be outside of science and nature. The persistence of so many people to try and find some proof of our souls does seem to indicate that a lot of us possess a willingness, or even desperation, to believe in the soul. Why is there such a strong desire to confirm the existence of the soul? The soul isn't just significant for a belief in an afterlife, it can be a pretty subversive element in the thinking of some individuals too.

Even though science tells us that a fetus is nothing more than a mass of tissue up until the third trimester, Christians will insist that 'life begins at conception'. When they have no solid or verifiable evidence on their side, they will fall back on the idea of the soul. One Christian website explains the concern of many believers:

To put it simply, Christians don't know what happens to the soul of an aborted fetus when their religion tells them that life begins at conception, and original sin means that everyone must repent and accept Christ as savior to make it into Heaven. Theological incoherencies are the actual reasons that many Christians espouse anti-choice sentiments. Women are deprived of their right to their own body because of religious doctrines and dogmas that are grossly lacking in any evidence or empirical support.

Another harmful soul-based assumption is also made regarding animals. Since Christians read in the bible that God only breathed a soul into Adam and Eve, they consider animals to be soulless automata, put here on Earth by God, for mankind's enjoyment. For centuries, Genesis 1:27-28 has been used to justify the maltreatment, senseless slaughter, and extinction of various species. If humans have souls and animals do not, it is tempting to think of ourselves as superior and thereby lose sight of the importance of conserving and respecting 'inferior' forms.

Documents recently leaked from the US Department of Defense intelligence briefings for the Iraq war in 2003 feature multiple inspirational bible verses [4], indicating that the war certainly held some religious significance to more than a few government officials. Other news tells us how American soldiers were encouraged to evangelize to Afghanistan residents [5], fearing for their unsaved souls. The concept of the soul is not only philosophical and mysterious, it's downright dangerous when it influences the thinking of many individuals.

IV. An Unnecessary Idea

The soul may be useful as a poetic idea, but taken as anything more, it is a source of confusion, irrational faith, and sometimes even oppression and intolerance. We don't need it to explain our thoughts, consciousness, experiences, or anything of the sort. Like the idea of god, it was something not fully understood or defined from the very beginning, and as time progresses, it only seems to become more and more vague. The search for the soul will probably never yield any results, because what we are searching for is a shadow of things we already know to exist, and the available evidence gives no strong suspicion that anything other than natural processes are at work.

1. Anonymous. (2008) More Americans Believe in the Devil, Hell and Angels.... HarrisInteractive. Retrieved May 19, 2009.
2. Hitt, J. (1999) This Is Your Brain on God. Wired.com. Retrieved May 19, 2009.
3. Fleischmann, R. Unborn Child's Soul from Abortion or Miscarriage. Christian Life Resources. Retrieved May 19, 2009.
4. Draper, R. (2009) And He Shall Be Judged. GQ. Retrieved May 19, 2009.
5. Grim, R. (2009) Soldiers In Afghanistan Given Bibles, Told To "Hunt People For Jesus". Retrieved May 19, 2009.