How Much Does a Soul Weigh?

How Much Does a Soul Weigh? March 6, 2023

What is the weight of a soul

In 1901 a physician from Haverhill, Massachusetts, named Duncan MacDougall became curious about the possible weight of a soul. As a staunch supporter of the scientific method, he decided to get his hands dirty and get to the bottom of the question. He reasoned that if souls were part of a person’s physical body, then they should have some physical weight. MacDougall conducted a series of very controversial experiments to calculate this theoretical mass.

The Soul Experiments

Duncan ran six experiments where he weighed nursing home patients suffering from terminal illnesses. He chose individuals dying from immobilizing diseases such as tuberculosis and diabetes since movement would mess up the measurements. In their last moments, the patients were carried, bed and all, to a scale where their passage from this life to the next was observed under scientific scrutiny.

The results of the experiment were as follows.

“One of the patients lost weight but then put the weight back on, and two of the other patients registered a loss of weight at death but a few minutes later lost even more weight. One of the patients lost “three-fourths of an ounce” (21.3 grams) in weight, coinciding with the time of death. MacDougall disregarded the results of another patient on the grounds the scales were “not finely adjusted”, and discounted the results of another as the patient died while the equipment was still being calibrated.”

He also tested the idea that humans are the only creatures on earth with a soul. To do so, he weighed fifteen dogs as they died. Although, it’s said he wanted to use poor beasts who were dying from diseases. It’s generally thought he poisoned them. According to his results, “none of the dogs lost any weight after death,” which he claimed confirmed the hypothesis.

Despite MacDougall’s tenacity for the truth, his experiments are considered inconclusive at best. Many say that the way he went about the investigation was unscientific and contaminated by biased interpretations. However, despite the inconclusive nature of his work, the experiment captured the imaginations of the masses and is where the myth that a soul weighs 21 grams came from.

What is a Soul?

One of the most significant objections to his experiment critiques the premise itself. Proponents of this position argue that MacDougall’s experiments were doomed to fail because he fundamentally misunderstood what a soul is. You see, his hypothesis was based on the Biblical idea of a soul, which is not described as the kind of thing with weight.

In the Bible, a soul is the spiritual side of you. It’s the nonphysical part of a person that gives the body life and lives on after the physical returns to dust.

The soul first enters the Biblical stage in Genesis 2:7, when God breathed life into Adam.

“Then the LORD God formed a man from the dust of the ground and breathed into his nostrils the breath of life, and the man became a living being.”

Unlike an organ or personality trait, the soul is not just a small piece that helps the overall machine function. Your soul is you; it’s what gives you your individuality. As George MacDonald once said, “You don’t have a soul. You are a Soul. You have a body.”

Where Did he Get The Idea of a Weighty Soul?

So, if a soul is never associated with anything that could be considered material, why did MacDougall think it could have weight?

Well, in order to answer this question, we need to travel back in time to ancient Egypt.

In the Book of the Dead (an Egyptian religious text), it’s written that the deceased make their way to the afterlife, where their soul is weighed against a feather. If the person’s soul is lighter, they are allowed to pass on. However, if it were heavier, Ammit, a horrifying alligator dog monster, would consume it.

This concept does not exist in the Bible, but it did find its way into Christian art and culture. For example, there are several paintings with Michal, the archangel weighing the souls of humanity on judgment day. There is also a second-century apocryphal text called the Testament of Abraham, which describes human souls being weighed. Consequently, MacDougall’s hypothesis likely had more of a foundation in popular Christian culture than in the Biblical text.

Living in Light of Eternity

I find Duncan MacDougall’s quest for the weight of a soul conflicting, to say the least. On the one hand, I can’t help but question the validity of his hypothesis, and I have a severe problem with the ethics of his work. However, at the same time, I admire his desire to find the spiritual realities hidden within the physical world.

Many Christians of modernity have become comfortable living with a materialistic view of the world. Me included.

Yes…. We believe in God, go to church, and pray at every meal. Yet, at the same time, we go through much of our life focused and consumed with the physical. For example, have you ever heard someone say something along these lines?

“I know the Bible tells me all about who God is, who I am, how I should live, and how to get to know God. But man…. it’s boring and I’m just too focused on all the physical stuff I do to read it.”        

We can often find the motivation to watch shows, take on too much work, or think deeply about how we will spend the next five years. Yet, when it comes to our spiritual needs and responsibilities, we tend to forget or sacrifice them. It’s hard to read the Bible after work, sacrifice a weekend for religious reasons, or sit quietly processing the current state of our eternal soul.

In his book Marriage in Light of Eternity Francis Chan pointed out the absurdity of this habit.

“People accuse me of going overboard in preparing for my first ten million years in eternity. In my opinion, people go overboard in worrying about their last ten years on earth.”

The Physical/Spiritual Dichotomy

We exist in a world that is both spiritual and physical. Since we’re here, taking care of the physical elements of reality is essential. However, at the same time, let’s not ignore the spiritual essence of God’s creation.

As we go about our day-to-day, we would be remiss to forget our status as mere strangers passing through a foreign land. We should also remember that the spiritual world is not as far off as it might seem.

“Do not forget to show hospitality to strangers, for by so doing some people have shown hospitality to angels without knowing it.” -Hebrews 13:2


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