The second of Naphtali Phillips and Rachel Seixas Phillips’s eleven children, Aaron was born in Philadelphia and brought up in New York. Among his siblings was Isaac Phillips. Aaron’s father became the first American born parnas of Congregation Mikveh Israel, launched the National Advocate, a Democratic newspaper that he edited for many years, and later served as a clerk in the New York Customs Office.

Passed down in family lore, recorded by Aaron’s nephew, N. Taylor Phillips, came a story that paints Aaron as a rather mischievous child. At Congregation Shearith Israel’s Mill Street synagogue, beneath each seat was a space for storing books and a tallit, accessed by lifting the seat. It seems Aaron’s favorite target was an older member of the congregation, and one day Aaron arrived early and placed a black cat in the storage area beneath this gentleman’s seat. When the gentleman arrived and raised the seat, the cat escaped, ran around the synagogue and caused quite a stir.

Aaron never married. Like his father and his brother Jonas, he worked in the New York Customs House.