American mathematician and computer scientist (1903–1995)
This article is about the mathematician and logician. For the president of the University of Georgia, see
Alonzo Church (college president). For the politician, see
A. C. Croom.
Alonzo Church was born on June 14, 1903, in
Washington, D.C., where his father, Samuel Robbins Church, was a
justice of the peace[5] and the judge of the Municipal Court for the District of Columbia. He was the grandson of Alonzo Webster Church (1829–1909),
United States Senate Librarian from 1881 to 1901, and great-grandson of
Alonzo Church, a professor of Mathematics and Astronomy and 6th President of the University of Georgia.[6] As a young boy, Church was partially blinded by an air gun accident.[7] The family later moved to Virginia after his father lost his position at the university because of failing eyesight. With help from his uncle, also named Alonzo Church, the son attended the private Ridgefield School for Boys in
Ridgefield, Connecticut.[8] After graduating from Ridgefield in 1920, Church attended Princeton University, where he was an exceptional student. He published his first paper on
Lorentz transformations[9] in 1924 and graduated the same year with a degree in mathematics. He stayed at Princeton for graduate work, earning a
Ph.D. in mathematics in three years under
Oswald Veblen.
He married Mary Julia Kuczinski in 1925. The couple had three children: Alonzo Jr. (1929), Mary Ann (1933), and Mildred (1938).
He taught philosophy and mathematics at Princeton for nearly four decades, from 1929 to 1967. He held the Flint Professorship of Philosophy and Mathematics at the
University of California, Los Angeles, 1967–1990.[11] He was a Plenary Speaker at the
ICM in 1962 in Stockholm.[12]
A deeply religious person, Church was a lifelong member of the
Presbyterian church.[18] He died on August 11, 1995, at the age of 92.[19] He is buried in
Princeton Cemetery.[20]
Mathematical work
Church is known for the following significant accomplishments:
The lambda calculus emerged in his 1936 paper showing the unsolvability of the Entscheidungsproblem. This result preceded Alan Turing's work on the
halting problem, which also demonstrated the existence of a problem unsolvable by mechanical means. Upon hearing of Church's work, Turing enrolled at Princeton later that year under Church for a Ph.D.[23] Church and Turing then showed that the lambda calculus and the
Turing machine used in Turing's halting problem were equivalent in capabilities, and subsequently demonstrated a variety of alternative "mechanical processes for computation." This resulted in the Church–Turing thesis.
The efforts for automatically generating a controller implementation from specifications originates from his ideas.[24]
In his honor the Alonzo Church Award for Outstanding Contributions to Logic and Computation was established in 2015 by the Association for Computing Machinery Special Interest Group for Logic and Computation (
ACM SIGLOG), the
European Association for Theoretical Computer Science (EATCS), the European Association for Computer Science Logic (
EACSL), and the
Kurt Gödel Society (KGS). The award is for an outstanding contribution to the field published within the past 25 years and must not yet have received recognition via another major award, such as the
Turing Award, the
Paris Kanellakis Award, or the
Gödel Prize.[25][26]
Philosophical work
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adding to it. (January 2023)
Church’s elaboration of a methodology involving the logistic method, his philosophical criticisms of nominalism and his defense of realism, his argumentation leading to conclusions about the theory of meaning, and the detailed construction of the Fregean and
Russellianintensional logics, are more than sufficient to place him high up among the most important philosophers of this century.
In addition to those he directly supervised, Church also had a large influence on other mathematicians and computer scientists.
Haskell Curry, who expanded on Church's ideas with the concept of
currying, stated that one of his textbooks, Introduction to Mathematical Logic (first published in 1944), was "written with the meticulous precision which characterizes the author's work generally."[29]
^Deutsch, Harry; Marshall, Oliver (2022),
"Alonzo Church", in Zalta, Edward N. (ed.), The Stanford Encyclopedia of Philosophy (Spring 2022 ed.), Metaphysics Research Lab, Stanford University, retrieved 2022-04-14
^Church, Alonzo (1962).
"Logic, arithmetic and automata"(PDF). Proceedings of the International Congress of Mathematicians. pp. 23–35. Archived from
the original(PDF) on 2013-12-28.
Alonzo Church interviewed by William Aspray on 17 May 1984. The Princeton Mathematics Community in the 1930s: An Oral-History Project, transcript number 5.
Church, A. (1950). "On Carnap's Analysis of Statements of Assertion and Belief". The Journal of Symbolic Logic. 10 (5): 97–99.
doi:
10.2307/3326684.
JSTOR3326684.