McCarthy created the term "artificial intelligence" and was a towering figure in computer science at Stanford most of his professional life. In his career, he developed the programming language LISP, played computer chess via telegraph with opponents in Russia and invented computer time-sharing.

John McCarthy, a professor emeritus of computer science at Stanford, the man who coined the term "artificial intelligence" and subsequently went on to define the field for more than five decades, died suddenly at his home in Stanford in the early morning Monday, Oct. 24. He was 84.

McCarthy was a giant in the field of computer science and a seminal figure in the field of artificial intelligence. While at Dartmouth in 1955, McCarthy authored a proposal for a two-month, 10-person summer research conference on "artificial intelligence" – the first use of the term in publication.

In proposing the conference, McCarthy wrote, "The study is to proceed on the basis of the conjecture that every aspect of learning or any other feature of intelligence can in principle be so precisely described that a machine can be made to simulate it." The subsequent conference is considered a watershed moment in computer science.

In 1958, McCarthy invented the computer programming language LISP, the second oldest programming language after FORTRAN. LISP is still used today and is the programming language of choice for artificial intelligence.

He also developed the concept of computer time-sharing in the late 1950s and early 1960s, an advance that greatly improved the efficiency of distributed computing and predated the era of cloud computing by decades.

"A bunch of people decided that time-sharing was clearly the way to work with a computer, but nobody could figure out how to make it work for general purpose computing – nobody except John," said Les Earnest, a senior research scientist emeritus at Stanford and an early collaborator at the Stanford Artificial Intelligence Laboratory (SAIL) with McCarthy.

'Programs with Common Sense'

In 1960, McCarthy authored a paper titled, "Programs with Common Sense," laying out the principles of his programming philosophy and describing "a system which is to evolve intelligence of human order."

McCarthy garnered attention in 1966 by hosting a series of four simultaneous computer chess matches carried out via telegraph against rivals in Russia. The matches, played with two pieces per side, lasted several months. McCarthy lost two of the matches and drew two. "They clobbered us," recalled Earnest.

Chess and other board games, McCarthy would later say, were the "Drosophila of artificial intelligence," a reference to the scientific name for fruit flies that are similarly important in the study of genetics.

McCarthy would later develop the first "hand-eye" computer system in which a computer was able to see real 3D blocks via a video camera and control a robotic arm to complete simple stacking and arrangement exercises.

Professionally, McCarthy was known for intense focus, a quality easily misunderstood. "John was very focused on what he was working on at all times. If you engaged him in a topic he was not interested in, he would sometimes turn away without saying a thing," said Earnest. "It was his way of staying on focus."

Ed Feigenbaum, professor emeritus of computer science at Stanford and a colleague recruited by McCarthy in the 1960s, recalled a softer side: "He could be blunt, but John was always kind and generous with his time, especially with students, and he was sharp until the end. He was always focused on the future. Always inventing, inventing, inventing. That was John."

One project that McCarthy returned to near the end of his life was a paper he had written in the early 1970s exploring the practicality of interstellar travel. He wrote: "We show that interstellar travel is entirely feasible with only small improvements in present technology provided travel times of several hundred to several thousand years are accepted."

"John's motivation for writing it in the first place was annoyance with what he claimed were faulty [critical] analyses published at the time.  He resurrected it out of frustration that no one had corrected these analyses over the intervening decades," wrote Bill Gosper, a colleague from SAIL, in an email.

Ardent optimist

McCarthy was known as well for wanting to bring scientific rigor to every aspect of life and for his wry, often self-deprecating sense of humor. This humor was perhaps best exemplified in a personal philosophy he termed "radical optimism" – a positive outlook so strong that he said, "Everything will be OK even if people don't take my advice," said daughter Susan McCarthy. "And, he was a loving father, too."

John McCarthy was born on Sept. 4, 1927, in Boston. He earned his undergraduate degree from the California Institute of Technology in 1948 and his PhD at Princeton in 1951, both in mathematics. He was an instructor at Princeton from 1951 until 1953 when he came to Stanford as an assistant professor. In 1955, he left for Dartmouth and then for MIT before returning to Stanford for good in 1962 as a full professor of computer science. He retired Jan. 1, 2001.

During his remarkable career, McCarthy co-founded the MIT Artificial Intelligence Project and what became the Stanford Artificial Intelligence Lab, serving as director at Stanford from 1965 until 1980. He was named the Charles M. Pigott Professor at the Stanford School of Engineering in 1987, before stepping down in 1994.

The Association of Computing Machinery honored McCarthy with the A. M. Turing Award in 1971, the highest recognition in computer science. He received the Kyoto Prize in 1988 and the National Medal of Science in 1990, the nation's highest technical award. He was a member of the National Academy of Sciences, the National Academy of Engineering and the American Academy of Arts and Sciences.

John McCarthy is survived by his third wife, Carolyn Talcott of Stanford; two daughters, Susan McCarthy of San Francisco and Sarah McCarthy of Nevada City, Calif.; a son, Timothy Talcott McCarthy of Stanford; a brother, Patrick, of Los Angeles; two grandchildren, Kitty McCarthy of San Francisco and Joseph Gunther of New York City; and his first wife, Martha Coyote. McCarthy's second wife, Vera Watson, died in 1978 in a mountain-climbing accident attempting to scale Annapurna in Nepal.

A memorial service will be held at a future date.