3/8/00

Eileen
Walsh, News Service (650) 725-1949;

e-mail: [email protected]

**Noted logician K. Jon Barwise dies**

K. Jon Barwise, a logician renowned for his
research in mathematical logic, his ingenuity in
applying mathematical techniques to outstanding
problems in other disciplines, and his pioneering
efforts in logic pedagogy, died of cancer March 4
in Bloomington, Ind. He was 57.

Barwise was College Professor of Philosophy,
Computer Science and Mathematics at Indiana
University. He joined the faculty at Indiana
University in 1990. Between 1983 and 1990, he was
a professor of philosophy at Stanford, where he
was a co-founder and first director of the Center
for the Study of Language and Information, and
the first director of the Symbolic Systems
Program.

"From the European perspective,"
said Johan van Benthem of the University of
Amsterdam, "Jon was one of those people who
define a whole field. Many students and
colleagues on other continents who had never even
met him felt their work shaped by the force of
his ideas and personality because of the power
of his publications."

Barwise was born in Independence, Mo., on June
29, 1942, to Kenneth T. and Evelyn Barwise. He
attended Yale University, where he received his
bachelor's degree in mathematics and philosophy
in 1963. He received his doctorate in mathematics
in 1967 from Stanford University, where he
studied logic under Professor Solomon Feferman of
Stanford and Professor Dana Scott, now at
Carnegie Mellon University. In 1992 he was
awarded an honorary doctorate from the University
of Pennsylvania.

"Jon was a builder," said Feferman.
"He liked carpentry and remodeling houses
and helping to create new academic projects and
programs, however much time and effort they took.
In pursuing these, he carried people along with
his convictions and enthusiasms, never insistent,
always good-humored."

Prior to Stanford, Barwise held appointments
in mathematics and computer science at Yale and
the University of Wisconsin. He also held
one-year visiting positions at Oxford University
and the University of California-Los Angeles, and
was twice a fellow at the Center for Advanced
Study in the Behavioral Sciences at Stanford.

Throughout his prolific career, Barwise sought
to develop a better theoretical understanding of
information content: how it is expressed in
language, computers or graphical representations,
and how it is transferred from one form of
representation to another. His first book, *Admissible
Sets and Structures* (1975), developed the
theory of admissible sets and applied it to
definability theory, a branch of logic devoted to
the precise study of the expressive power of
formal languages (for example, mathematical
languages). The techniques he pioneered in this
work are still being applied and extended today.

*Situations and Attitudes* (1983), his
second book, coauthored with Professor John Perry
of Stanford, introduced the notion of situation
semantics, a broadly philosophical and
mathematical approach to the study of meaning in
natural (i.e., spoken human) languages. Situation
semantics and situation theory are today one of
several tools used by linguists studying the
rules that determine the information content of
sentences in a language.

Barwise's third book, *The Liar: An Essay on
Truth and Circularity* (1987), coauthored with
Professor John Etchemendy of Stanford, combined
ideas from situation semantics and insights of
the British philosopher of language J. L. Austin
to study circular or self-referential claims,
such as the so-called Liar Paradox ("What I
am now saying is false"). New developments
in non-well-founded set theory by the
mathematician Peter Aczel of Manchester
University were used to give a precise,
non-paradoxical model of these circular claims.

With Professor Larry Moss of Indiana, Barwise
continued to pursue the theory of
non-well-founded sets and to apply it to a wide
variety of circular phenomena in computer
science, linguistics and logic. This work was
presented in a fourth book, *Vicious Circles:
On the Mathematics of Circular Phenomena*
(1996).

In his fifth research monograph, *Information
Flow: The Logic of Distributed Systems*
(1997), coauthored with Jerry Seligman, Barwise
proposed a theory of how information flows
through complex systems as diverse as computers
and natural languages. Central to this theory is
the notion of an information channel, capable of
preserving information as it is transmitted
through a complex, causally interacting system.

Barwise's extensive contributions to logic
went well beyond the topics of these five
monographs. He authored or co-authored nearly 100
articles on topics ranging from infinitary logic
(the logic of formal languages allowing
infinitely long sentences) to generalized
quantifiers (phrases like "most
people," "few dogs," "many
prime numbers") and heterogeneous inference
(reasoning that employs information represented
in more than one form, such as a map and written
directions).

He also edited several landmark volumes in
logic, including *The Syntax and Semantics of
Infinitary Languages *(1968), *The Handbook
of Mathematical Logic* (1975), *Model-theoretic
Logics* (with Solomon Feferman, 1985) and *Logical
Reasoning with Diagrams* (with Gerard Allwein
of Indiana University, 1996).

In addition to his substantial research
contributions, Barwise was deeply committed to
the teaching of logic. With Etchemendy, he
developed numerous pieces of innovative
courseware to help convey abstract concepts in
logic. These were published with a series of
textbooks, including *The Language of
First-order Logic* (1990), *Tarski's World*
(1991), *Turing's World* (1993), *Hyperproof*
(1994) and *Language, Proof and Logic*
(2000).

"Jon always said that he considered his
most important contribution to logic to be his
development of new teaching techniques and
methods," said Etchemendy.

Barwise and Etchemendy shared the 1997 Educom
Medal for their contribution to logic pedagogy.
Educom is a nonprofit consortium of colleges,
universities and other organizations dedicated to
the transformation of higher education through
the application of information technologies. It
has 600 institutional members and nearly 100
corporate associates.

During the last year of his life, Barwise
conducted an extensive e-mail correspondence with
family, friends and colleagues, cataloging his
courageous efforts to deal with and surmount his
illness, and his philosophical reflections on
life, death and logic.

"Jon taught us how to die," said
Irene Scott, wife of Barwise's teacher Dana
Scott.

"Jon will be sorely missed as one of the
key thinkers and leaders pursuing a broad vision
of logic as an analysis of information and
cognition," said van Benthem. "My own
world suddenly seems lonelier."

Barwise is survived by his wife, Mary Ellen,
of Bloomington, and three children: Melanie of
Madison, Wis.; Jon Russell of Portland, Ore.; and
Claire of Bloomington.

A memorial service will be held at Indiana
University in Bloomington on Sunday, April 30.
For more information call (812) 855-1093, (812)
855-7088, or see
http://www-vil.cs.indiana.edu/barwise.html.

The family prefers donations to the Ting-Sha
Institute (Cancer Retreat Center), P.O. Box 226,
Pt. Reyes Station, Calif. 94956.

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