Early life and education
John McCarthy was born in Boston, Massachusetts, on September 4, 1927, to an Irish immigrant father and a Lithuanian Jewish immigrant mother, John Patrick and Ida Glatt McCarthy. The family was obliged to relocate frequently during the Great Depression, until McCarthy's father found work as an organizer for the Amalgamated Clothing Workers in Los Angeles, California. His father came from the fishing village of Cromane in County Kerry, Ireland. His mother died in 1957.
McCarthy was exceptionally intelligent, and graduated from Belmont High School two years early. McCarthy was accepted into Caltech in 1944.
McCarthy showed an early aptitude for mathematics; during his teens he taught himself college mathematics by studying the textbooks used at the nearby California Institute of Technology (Caltech). As a result, he was able to skip the first two years of mathematics at Caltech.
McCarthy was suspended from Caltech for failure to attend physical education courses. He then served in the US Army and was readmitted, receiving a B.S. in mathematics in 1948.
It was at Caltech that he attended a lecture by John von Neumann that inspired his future endeavors.
McCarthy initially completed graduate studies at Caltech before moving to Princeton University. He received a Ph.D. in mathematics from the institution in 1951 as a student of Solomon Lefschetz.