Chiropractic's uniqueness lies not in its use of SMT, but in its theoretical reason for doing so. just as prescientific osteopathy found its justification in the "rule of the artery" (the belief that manipulation improved circulation by reducing muscle spasms), chiropractic is based upon the "rule of the nerve" (the belief that SMT has important effects upon "nerve flow").
The word chiropractic literally means "done by hand." The term was adopted by chiropractic's founder, Daniel David Palmer. Palmer was a layman with an intense interest in metaphysical health philosophies such as magnetic healing (Mesmer's "animal magnetism"), phrenology, and spiritualism. In 1895, he claimed to have restored the hearing of a nearly deaf janitor by manipulating the man's spine.
Obsessed with uncovering "the primary cause of disease," Palmer theorized that "95 percent of all disease" was caused by spinal "subluxations" (partial dislocations) and the rest by "luxated bones elsewhere in the body." Palmer speculated that subluxations impinged upon spinal nerves, impeding their function, and that this led to disease. He taught that medical diagnosis was unnecessary, that one need only correct the subluxations to liberate the body's own natural healing forces. He disdained physicians for treating only symptoms, alleging that, in contrast, his system corrected the cause of disease.
Palmer did not employ the term subluxation in its medical sense, but with a metaphysical, pantheistic meaning. He believed that the subluxations interfered with the body's expression, of the "Universal Intelligence" (God), which Palmer dubbed the "Innate Intelligence." (soul, spirit, or spark of life). [9] Palmer's notion of having discovered a way to manipulate metaphysical life force is sometimes referred to as his "biotheology."