At the center of the debate over complementary and alternative medicine--from acupuncture and chiropractic treatments to homeopathy and nutritional supplements--is how to scientifically measure the effectiveness of a particular treatment. Fourteen scholars from the fields of medicine, philosophy, sociology, and cultural and folklore studies examine that debate, and the clash between growing public support and the often hostile stance of clinicians and medical researchers.

Proponents and critics have different methodologies and standards of evidence--raising the question of how much...