Christopher Longuet-Higgins


Born: 11 April, 1923 Died: 27 March, 2004, aged 80

HUGH Christopher Longuet-Higgins, always known as Christopher, was an exceptional scholar who made important scientific advances in two quite different disciplines, chemistry and artificial intelligence: many people think he was unlucky not to receive a Nobel Prize for his work in the former. He was one of the last great polymaths.

Born in Kent, he attended Winchester, where, as a schoolboy, he solved a problem concerning four-dimensional solids which, unbeknown to him, had first been cracked only a few months earlier. While still an undergraduate at Oxford, where he simultaneously studied both chemistry and music, he published a landmark paper in the Journal of the Chemical Society on the structure of an unusual molecule called diborane. He stayed at Oxford for a DPhil under the supervision of Charles Coulson and together they derived many important theorems concerning the electronic states of aromatic molecules.

After Oxford, Christopher had short spells at Chicago and Manchester universities, before moving in 1952 to a chair in theoretical physics at King’s College, London. Two years later, he became the John Humphrey Plummer Professor of Theoretical Chemistry at Cambridge. The department he joined was eminent when he arrived, and he built it further so that it became arguably the outstanding theoretical chemistry department in the world.

Therefore, it was a surprise to most chemists when, in 1967, he decided to move into the field of artificial intelligence, giving up his Cambridge post for a Science Research Council senior research fellowship, and one year later a Royal Society research professorship, at Edinburgh University. He showed a formidable talent in his new field.

With Richard Gregory and Donald Michie, he founded the department of machine intelligence and perception in Edinburgh, and he took a leading role in starting the school of epistemics, an interdisciplinary group, which brought together people with an interest in the mind. Along with postgraduate and postdoctoral workers, he made important early contributions in informatics, neural networks and language generation by computer. Christopher, unsure what to call the sort of research he conducted, first coined the term "cognitive science" in a paper in 1973.

In 1974, he transferred his Royal Society fellowship to Sussex University, where he joined the experimental psychology group in the school of biological sciences. He continued his work on artificial intelligence and, from 1984 to 1986, was director of the Institute of Cognitive and Information Sciences at Sussex whose aim was to bring together widely dispersed groups in computer engineering, computer science, linguistics and experimental psychology.

His musical talents were combined with his academic skills in an influential paper on classical harmony, and he developed a computer program to determine key-signatures, accidentals, and bar lines from the keyboard strokes of performances of classical music.

These days, Christopher’s postgraduate students and postdoctoral associates hold many important posts in the academic world. He was a tough supervisor, and an aggressive contributor to colloquia and scientific meetings; many an invited speaker wilted under his comments. His penultimate scientific paper, published in 1995, had the title "150 words on Consciousness"; he never wasted words in his writings.

His full list of awards and prizes is too long to be addressed here. He was elected a fellow of the Royal Society in 1958, and a foreign associate of the US Academy of Sciences in 1968. He became a fellow of the Royal Society of Arts in 1970, and was a governor of the BBC from 1979 to 1984. He had honorary doctorates from the universities of York, Essex, Bristol, Sussex and Sheffield, the last being in music.

During his time at Oxford, he explored the possibility of becoming a professional musician; science was lucky that he settled for being an inspired amateur in that field.