This book is designed to inform, engage, and stimulate discussions among its readers. Collins and his collaborators have included authoritative statements and analysis by renowned scholars. A distinctive characteristic of the whole anthology is the range of interpretations of classic and recent research. The book offers a full spectrum of emotionally charged theories. Each section presents a set of conflicting arguments to show the state of debates on these highly controversial issues. Extensive commentary by the editors leads the reader through this treasury of theories and dramatically highlights the development of the field.