Proponents often cite acupuncture’s ancient heritage as a virtue, but it is more of a vice. Acupuncture was developed in a pre-scientific culture, before anything significant was understood about biology, the normal functioning of the human body or disease pathology. The healing practices of the time were part of what is called philosophy-based medicine, to be distinguished from modern science-based medicine. Philosophy-based systems began with a set of ideas about health and illness and based their treatments on those ideas. The underlying assumptions and the practices derived from them were never subjected to controlled observation or anything that can reasonably be called a scientific process.
An example from Western culture of philosophy-based medicine was the humoral theory – the notion that health was the result of the four bodily humors being in proper balance while illness reflected one or more of the humors being out of balance. Treatments therefore sought to increase or decrease one or more of the humors (such as the practice of bloodletting) to re-establish balance. The humoral theory survived for several thousand years in Western societies, perpetuated by culture and the power of deception inherent in anecdotal evidence.
Acupuncture is based upon the Eastern philosophy of chi (also spelled qi), which is the Chinese term for the supposed life force or vital energy that animates living things. In Traditional Chinese Medicine (TCM) chi flows through pathways in the body known as meridians. Illness results from the flow of chi through the meridians being blocked, or by the two types of chi (yin and yang) being out of balance. Acupuncture is the practice of placing thin needles at acupuncture points, which are said to coincide with points at which meridians cross, to improve the flow and restore the balance of chi.
There is no more reason to believe in the reality of chi than there is in the four humors, or in the effectiveness of acupuncture than the effectiveness of bloodletting.