Soul’s Weight: The Experiment of 21 Grams

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

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

The soul is a concept as mysterious as it is vague and confused, and that is why it is so scorned by science, charged with describing nature from small observations and prudent assumptions, 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 twentieth century a doctor named Duncan MacDougall set out to break with this logic by looking for evidence about the existence of the disembodied 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 imprint on the body that had housed it, it should be found at the moment of death, which is when it leaves the body to move to another plane of the reality. For that reason, he maintained that the death of the people not only supposes the disappearance of the voluntary movements and the cease of the mental activity, but it had repercussions in 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, compress millennia of affirmations about the hereafter in the discreet movement of a needle. This was what 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 performed?

Duncan MacDougall wanted to collect his evidence about the existence of the human soul using as a tool a complex system of scales incorporated into a kind of bed. In this way, he convinced six people who were dying to spend their last hours in that type of structure, which allowed him to register the weight of their bodies from a few hours before their deaths until just after.

From these results, MacDougall concluded that the soul weighs approximately 21 grams, which is the variation he could 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 root strongly in popular culture, which explains that references to this experiment appear in musical pieces, novels and movies.

The controversy

While it is true that the New York Times article on Duncan MacDougall and the weight of the soul had a great impact, it is also true that it was not positively accepted unanimously. The scientific community of that time already distrusted enormously the experimental incursions in the realm of the supernatural, and the experiment of 21 grams was based on ideas that directly attacked the principle of parsimony, used in science to point out that explanations 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 made 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 dying, which would indicate that, as certain religious beliefs maintain, non-human animals lack soul. As expected, this did nothing but add fuel to the fire.

Does this sound reasonable?

MacDougall hoped to take advantage of the recent technological advances and the refinement of the scientific method to access a type of knowledge that for millennia had been unattainable for humanity, 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 is beyond the realm of the physical. Considering that, it is not strange that the conclusions reached were so incendiary.

An experiment created by irrational beliefs

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

However, beyond the consideration of the many mistakes that were made during the experiments, there remained other fundamental philosophical questions: Is not learning about the immaterial world and mystery the most ambitious type of knowledge that science can reach? Does not the fact that the nature of the human soul has been discussed for millennia make this subject an especially interesting subject for the scientific community?

The answer is no

In hindsight, and from what is known about the experiments conducted by Duncan MacDougall, it is clear that the large number of methodological failures mean that we can not even take seriously the claim that bodies lose about 21 grams at death. However, what makes these researches only valuable as a historical curiosity are not these errors, but the objectives towards which they pointed.

Soul does not weigh 21 grams

To give an explanation about a process linked to the world of the physical, one can not appeal to the world of the immaterial but seek the answers in the nature that surrounds us.

This is what, for example, the physician Augustus P. Clarke, who linked weight loss with an increase in sweating right after death, due to the general warming of the body as the organs in charge of the ventilation, that is, the lungs. In turn, Clarke pointed to the fact that dogs do not have sweat glands scattered throughout the body, which would explain why there was not a change in their weight after they died.

Of course, the very definition of the concept of soul is very plural, conflicting and contains many contradictions (how can something incorporeal inhabit the body of living beings?). However, what makes his 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 and, therefore, can not be measured and can not be modified by what It happens to the body.

If we assume that an extraordinary statement needs to be sustained from equally extraordinary evidence, we will see that there is an obvious leap of faith that goes from the realization 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 virtually infinite number of questions that do not they can be answered based on more empirical tests.

After death, what do we have left?

The difference of 21 grams recorded by Duncan MacDougall was intended to be much more than justification of what led to the experiment (detect a change in weight before and after death) but was raised as a window to the world beyond . The hypothesis that was wanted to test could only be sustained on a system of religious beliefs accumulated during centuries, and lost all the sense when being separated of this one to be placed under the magnifying glass of the scientific method.

However, while it is true that the experiment of 21 grams has no scientific value, has shown an extraordinary robustness in surviving in the collective imagination of society. This is probably due to the fact that the beliefs about the soul that MacDougall had a hundred years ago are still very valid today.

Our cultural background makes us pay more attention to an apparently scientific article that confirms our beliefs than to a 200-page book written decades ago in which we talk about why science only deals with talking about processes based on what material. The scientific mentality may have many tools to perpetuate itself, but it is still not as seductive as certain ideas about the afterlife.