The weight of the soul, or the 21-gram experiment.

Myths and facts about the weight of the soul. How much does the human soul weigh?

For centuries, Western culture has harbored, among its repertoire of ideas and beliefs about the afterlife, the assumption that the essence of human beings lies in an immaterial substance to which the soul is attached, the assumption that the essence of human beings lies in an immaterial substance that we usually call the soul. soul. 

The soul is a concept as mysterious as it is imprecise and confusing, and that is why it is so disdained by science, in charge of describing nature from small observations and prudent assumptions, as well as used by religions, which in a very ambitious way appeal to the great mysteries that from an immaterial world seem to guide the order of the cosmos.

Soul, a concept in dispute

However, at the beginning of the 20th century, a physician named Duncan MacDougall set out to break with this logic by to look for proofs about the existence of the incorporeal essence of human beings in a simple experiment based on the use of scales. The idea from which this researcher started was that if the soul left some kind of trace in the body that had housed it, this must be found at the moment of death, which is when it leaves the body to move to another plane of reality. Therefore, he argued that the death of people not only entailed the disappearance of voluntary movements and the cessation of mental activity, but also had repercussions on the weight of the body.

A body that lacked the essence that defined it as something human, with intentions and will: the soul.

MacDougall wanted to weigh the soul, to compress millennia of claims about the afterlife into the discrete movement of a needle. It was this that led him to argue that the physical embodiment of the existence of the soul could be found in, more or less, 21 grams of difference..

How was the 21-gram experiment conducted?

Duncan MacDougall wanted to collect his evidence for the existence of the human soul by using as an instrument a complex system of scales built into a kind of bed. In this way, he convinced six people who were dying to spend their last hours in this type of structure, which allowed him to record the weight of their bodies. This allowed him to record the weight of their bodies from a few hours before their deaths until just after they died..

From these results, MacDougall concluded that the soul weighs approximately 21 grams, which is the variation he was able to observe through his research. This statement had a considerable impact on the press, which, through the New York Times echoed the news even before a version of it appeared in academic journals. Thus, the idea that the soul could weigh about 21 grams has taken strong root in popular culture, which explains why references to this experiment appear in musical pieces, novels and movies. This explains why references to this experiment appear in musical pieces, novels and films, the most notorious being 21 Grams by director Alejandro González Iñárritu.the most notorious being 21 grams by director Alejandro González Iñárritu.

The controversy

While it is true that the New York Times article on Duncan MacDougall and the weight of the soul had a lot of repercussion, it is also true that it was not received positively in a unanimous way. The scientific community at the time was already highly suspicious of experimental incursions into the realm of the supernatural, and the 21-gram experiment was based on ideas that went directly against the principle of parsimony, used in science to indicate that explanations of an objective fact should be as simple as possible. That is why the results obtained by this doctor divided the public into two polarized positions..

To reinforce his results, MacDougall carried out a variant of the experiment using dogs, to reach the conclusion that there was no change in the weight of these animals before and after death, which would indicate that, as certain religious beliefs maintain, non-human animals lack a soul. As is to be expected, this only added fuel to the fire, this only added fuel to the fire..

Does this sound reasonable?

MacDougall hoped to take advantage of (then) recent technological advances and the refinement of the scientific method to access a type of knowledge that for millennia had been unattainable to mankind, but which is related to a plane of existence associated with the eternal, the essence of human beings and, in general, entities that inhabit what lies beyond the realm of the physical. With that in mind, it is not surprising that the conclusions he reached were so incendiary..

An experiment mediated by irrational beliefs

On the one hand, the 21-grams experiment talks about dogmas, questions of faith, the essence of the human and certain elements related to the realm of the sacred.. On the other hand, it seemed to be an instrument to blur the limits of what can and should be studied scientifically. The mere fact that MacDougall wanted to investigate the soul through the scientific method was provocative, and many researchers were quick to point out a great number of methodological flaws in the procedures followed by Duncan.

However, beyond the consideration of the many mistakes that were made during the experiments, there remained other fundamental philosophical questions: Isn't learning about the immaterial world and mystery the most ambitious kind of knowledge that science can reach? Doesn't the fact that the nature of the human soul has been discussed for millennia make this subject of particular interest to the scientific community?

The answer is... no.

In retrospect, and from what is known about the experiments conducted by Duncan MacDougall, it is evident that the large number of methodological flaws make it so that we cannot even take seriously the claim that bodies lose about 21 grams at death.. However, what makes these investigations valuable only as a historical curiosity are not these errors, but the objectives towards which they were aimed.

The soul does not weigh 21 grams

In order to give an explanation about a process linked to the physical world, one cannot appeal to the immaterial world, but must look for answers in the nature that surrounds us.

This is what was done, for example, by the physician Augustus P. Clarke, who related Weight loss to an increase in sweating just after death, due in turn to the general warming of the body.This, in turn, is due to the general heating of the body as the organs in charge of ventilation, i.e. the lungs, no longer function. In turn, Clarke pointed to the fact that dogs do not have sweat glands distributed throughout the body, which would explain why there was no change in their weight after death.

Of course, the very definition of the concept of the soul is very plural, conflicting and contains many contradictions (how can something incorporeal inhabit the body of living beings). However, what makes its study not the task of science is the fact that when we talk about the soul, we are talking about something that has no physical entity. we are talking about something that has no physical entity and, therefore, can neither be measured nor can it be modified by what happens to the body.

If we assume that an extraordinary claim needs to be supported by equally extraordinary evidence, we will see that there is an obvious leap of faith from the observation of a change in weight to the idea that this is because the soul has left the body. In fact, in the case of concluding that the 21 grams serve as evidence that there is a supernatural entity that inhabits people, rather than offering an explanation to the observed fact we will be doing just the opposite: creating a practically infinite number of questions that cannot be answered from further empirical verifications.

After death, what is left for us?

The 21-gram difference recorded by Duncan MacDougall was intended to be much more than a justification for what led to the experiment (detecting a change in weight before and after death) but rather but was intended as a window into the world beyond.. The hypothesis to be tested could only be sustained on a system of religious beliefs accumulated over centuries, and it lost all meaning when separated from it to be placed under the magnifying glass of the scientific method.

However, although it is true that the 21-gram experiment has no scientific value, it has shown an extraordinary robustness when it comes to surviving in the collective imagination of society. This is probably due to the fact that the beliefs about the soul that MacDougall held a hundred years ago are still very much alive today. 

Nur cultural background makes us pay more attention to a seemingly scientific article that confirms our beliefs than to a 200-page book written decades ago that talks about why science is only concerned with material-based processes. than to a 200-page book written decades ago that talks about why science is only concerned with talking about material-based processes. The scientific mindset may have many tools to perpetuate itself, but it is still not as seductive as certain ideas about the afterlife.