### William Craig

It is with great sadness that we announce that our colleague William Craig died in the early hours of January 13, 2016. Professor Craig was an internationally renowned logician whose name is attached to one of the key results in the field, Craig’s Interpolation Theorem, which he proved in 1957.

Craig was also responsible for showing, in 1953, that every recursively enumerable theory is recursively axiomatizable. This result, which came to be called Craig’s Theorem, played an important role in philosophical debates about theoretical terms in scientific theories.

Professor Craig was born on November 13, 1918 in Nuremberg. There he attended a grammar school and a humanistic gymnasium until 1937. In July 1937 he emigrated to the United States and attended Cornell University where he earned, in 1940, a B.A. with major in philosophy and physics. He served in the U.S. Army from 1941 to 1945 and in the following years spent time at UC Berkeley (1940–1941), Harvard (1946–1948), the Swiss Federal Institute of Technology (1948–1949), Princeton (1949–1950), and again Harvard (1950–1951), where he obtained his Ph.D. in philosophy with a dissertation supervised by Quine.

He became mathematics instructor at Pennsylvania State University in 1951 and there he rose through the ranks, first as Assistant Professor of Mathematics (1952–1957) and then as Associate Professor (1957–1961). In 1960–1961 he spent a year of leave at UC Berkeley, and that led to his move to Berkeley as Professor of Philosophy in 1961. He was President of the Association of Symbolic Logic in 1959–1961 and President of the Pacific Division of the American Philosophical Association in 1978–9. He played an immense role in the development of logic at UC Berkeley, which he generously supported, and he remained an active presence in the logical community even after his retirement in 1989, until the end of his life.

His main contributions to logic were at the intersection of
proof theory, model theory, and algebraic logic. In addition to
the two fundamental articles on the interpolation theorem published in
1957 in the *Journal of Symbolic Logic*, Professor Craig was the author of
many articles in mathematical logic and of two books: *Logic in
algebraic form: Three languages and theories* (North Holland,
1974) and *Semi-Groups underlying first-order logic* (American
Mathematical Society, 2006).

In 2007, the Philosophy Department at UC Berkeley and the
Group in Logic and the Methodology of Science celebrated
Professor Craig’s achievements with a conference titled
“Interpolations”. A
special issue of *Synthese*,
containing the papers read at the
conference and additional contributions, was published in 2008.

January 14, 2016