Philip Howard Arnot was born in Placerville, CA, in February 1894, the son of Nathaniel D. Arnot, superior court judge in El Dorado and Alpine counties, California. He received his secondary education in Placerville, where he graduated from the Eldorado High School in 1912. Dr. Arnot graduated from the University of California Medical School in 1920, and was an intern and resident at University Hospital, 1919-1922. He was a visiting physician in obstetrics and gynecology at the Hospital for Children, chief of obstetrics and gynecology at St. Mary's Hospital, and a consultant in obstetrics at Franklin Hospital. Dr. Arnot was also a clinical professor in obstetrics and gynecology at UCSF. He published frequently on various topics in his field.

Dr. Arnot was member of the American Medical Association, the California Medical Association, the San Francisco Gynecology Society, and the Pacific Coast Gynecology and Obstetrics Society. He also belonged to the American College of Obstetricians and Gynecologies, and was a fellow of the American College of Surgeons. Dr. Arnot was a member of the Bohemian Club, and performed in the San Francisco Doctors' Symphony.