Most users of complementary and alternative medicine (CAM) approach it differently than physicians, because they employ informal knowledge, based on their experiences, beliefs, and values. Mary Ruggie stresses that, although physicians also use informal knowledge from their clinical experience to understand patients and their needs, they rely on formal knowledge, based on science, to understand medicine. Thus, if CAM is going to become a legitimate part of health care, physicians must insist that scientific research prove its safety and efficacy.