Arguments for the existence of God generally fall into certain categories (e.g. cosmological arguments, moral arguments, arguments from design, etc). But into which categories arguments for the existence of the soul fall into?
Allegedly the human soul has a mass of 21 grams. If so, then it must exist.
In 1901, Duncan MacDougall, a physician from Haverhill, Massachusetts, who wished to scientifically determine if a soul had weight, identified six patients in nursing homes whose death was imminent. Four were suffering from tuberculosis, one from diabetes, and one from unspecified causes. MacDougall specifically chose people who were suffering from conditions that caused physical exhaustion, as he needed the patients to remain still when they died to measure them accurately. https://en.wikipedia.org/wiki/21_grams_experiment
The argument is not very good because it was hardly possible for McDougall to determine the weight of human bodies with the required precision.