Richard Jeffrey
Encyclopedia
Richard C. Jeffrey was an American
philosopher, logician, and probability theorist
. He was a native of Boston, Massachusetts.
Jeffrey served in the U.S. Navy during World War II
. As a graduate student he studied under Rudolf Carnap
, and Carl Hempel. He received his M.A.
from the University of Chicago
in 1952 and his Ph.D.
from Princeton in 1957. After holding academic positions at MIT, City College of New York
, Stanford University
, and the University of Pennsylvania
, he joined the faculty of Princeton University
in 1974 and became a professor emeritus
there in 1999. He was also a visiting professor at the University of California, Irvine
.
As a philosopher, Jeffrey specialized in epistemology and decision theory
. He is perhaps best known for defending and developing the Bayesian approach to probability—specifically, for inventing "Jeffrey conditioning" (which he referred to as "probability kinematics"), a way of modeling the change in the probability
of a proposition
in light of new evidence
.
Jeffrey also wrote or co-wrote two widely used and influential logic
textbooks: Formal Logic: Its Scope and Limits, a basic introduction to logic, and Computability and Logic, a more advanced text dealing with, among other things, the famous negative results of twentieth century logic such as Gödel's incompleteness theorems
and Tarski's indefinability theorem
.
Jeffrey, who died of lung cancer
at the age of 76, was known for his sense of humor, which often came through in his breezy writing style. In the preface of his posthumously published Subjective Probability, he refers to himself as "a fond foolish old fart dying of a surfeit of Pall Malls
" (p. xii).
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
philosopher, logician, and probability theorist
Probability theory
Probability theory is the branch of mathematics concerned with analysis of random phenomena. The central objects of probability theory are random variables, stochastic processes, and events: mathematical abstractions of non-deterministic events or measured quantities that may either be single...
. He was a native of Boston, Massachusetts.
Jeffrey served in the U.S. Navy during World War II
World War II
World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...
. As a graduate student he studied under Rudolf Carnap
Rudolf Carnap
Rudolf Carnap was an influential German-born philosopher who was active in Europe before 1935 and in the United States thereafter. He was a major member of the Vienna Circle and an advocate of logical positivism....
, and Carl Hempel. He received his M.A.
Master of Arts (postgraduate)
A Master of Arts from the Latin Magister Artium, is a type of Master's degree awarded by universities in many countries. The M.A. is usually contrasted with the M.S. or M.Sc. degrees...
from the University of Chicago
University of Chicago
The University of Chicago is a private research university in Chicago, Illinois, USA. It was founded by the American Baptist Education Society with a donation from oil magnate and philanthropist John D. Rockefeller and incorporated in 1890...
in 1952 and his Ph.D.
Ph.D.
A Ph.D. is a Doctor of Philosophy, an academic degree.Ph.D. may also refer to:* Ph.D. , a 1980s British group*Piled Higher and Deeper, a web comic strip*PhD: Phantasy Degree, a Korean comic series* PhD Docbook renderer, an XML renderer...
from Princeton in 1957. After holding academic positions at MIT, City College of New York
City College of New York
The City College of the City University of New York is a senior college of the City University of New York , in New York City. It is also the oldest of the City University's twenty-three institutions of higher learning...
, Stanford University
Stanford University
The Leland Stanford Junior University, commonly referred to as Stanford University or Stanford, is a private research university on an campus located near Palo Alto, California. It is situated in the northwestern Santa Clara Valley on the San Francisco Peninsula, approximately northwest of San...
, and the University of Pennsylvania
University of Pennsylvania
The University of Pennsylvania is a private, Ivy League university located in Philadelphia, Pennsylvania, United States. Penn is the fourth-oldest institution of higher education in the United States,Penn is the fourth-oldest using the founding dates claimed by each institution...
, he joined the faculty of Princeton University
Princeton University
Princeton University is a private research university located in Princeton, New Jersey, United States. The school is one of the eight universities of the Ivy League, and is one of the nine Colonial Colleges founded before the American Revolution....
in 1974 and became a professor emeritus
Emeritus
Emeritus is a post-positive adjective that is used to designate a retired professor, bishop, or other professional or as a title. The female equivalent emerita is also sometimes used.-History:...
there in 1999. He was also a visiting professor at the University of California, Irvine
University of California, Irvine
The University of California, Irvine , founded in 1965, is one of the ten campuses of the University of California, located in Irvine, California, USA...
.
As a philosopher, Jeffrey specialized in epistemology and decision theory
Decision theory
Decision theory in economics, psychology, philosophy, mathematics, and statistics is concerned with identifying the values, uncertainties and other issues relevant in a given decision, its rationality, and the resulting optimal decision...
. He is perhaps best known for defending and developing the Bayesian approach to probability—specifically, for inventing "Jeffrey conditioning" (which he referred to as "probability kinematics"), a way of modeling the change in the probability
Probability
Probability is ordinarily used to describe an attitude of mind towards some proposition of whose truth we arenot certain. The proposition of interest is usually of the form "Will a specific event occur?" The attitude of mind is of the form "How certain are we that the event will occur?" The...
of a proposition
Proposition
In logic and philosophy, the term proposition refers to either the "content" or "meaning" of a meaningful declarative sentence or the pattern of symbols, marks, or sounds that make up a meaningful declarative sentence...
in light of new evidence
Evidence
Evidence in its broadest sense includes everything that is used to determine or demonstrate the truth of an assertion. Giving or procuring evidence is the process of using those things that are either presumed to be true, or were themselves proven via evidence, to demonstrate an assertion's truth...
.
Jeffrey also wrote or co-wrote two widely used and influential logic
Logic
In philosophy, Logic is the formal systematic study of the principles of valid inference and correct reasoning. Logic is used in most intellectual activities, but is studied primarily in the disciplines of philosophy, mathematics, semantics, and computer science...
textbooks: Formal Logic: Its Scope and Limits, a basic introduction to logic, and Computability and Logic, a more advanced text dealing with, among other things, the famous negative results of twentieth century logic such as Gödel's incompleteness theorems
Gödel's incompleteness theorems
Gödel's incompleteness theorems are two theorems of mathematical logic that establish inherent limitations of all but the most trivial axiomatic systems capable of doing arithmetic. The theorems, proven by Kurt Gödel in 1931, are important both in mathematical logic and in the philosophy of...
and Tarski's indefinability theorem
Tarski's indefinability theorem
Tarski's undefinability theorem, stated and proved by Alfred Tarski in 1936, is an important limitative result in mathematical logic, the foundations of mathematics, and in formal semantics...
.
Jeffrey, who died of lung cancer
Lung cancer
Lung cancer is a disease characterized by uncontrolled cell growth in tissues of the lung. If left untreated, this growth can spread beyond the lung in a process called metastasis into nearby tissue and, eventually, into other parts of the body. Most cancers that start in lung, known as primary...
at the age of 76, was known for his sense of humor, which often came through in his breezy writing style. In the preface of his posthumously published Subjective Probability, he refers to himself as "a fond foolish old fart dying of a surfeit of Pall Malls
Pall Mall (cigarette)
Pall Mall cigarettes are a brand of cigarettes produced by R. J. Reynolds Tobacco Company in Winston-Salem, North Carolina, and internationally by British American Tobacco at multiple sites.- History :...
" (p. xii).
Selected bibliography
- Formal Logic: Its Scope and Limits. 3rd ed. McGraw Hill, 1990. ISBN 0-07-032357-7
- Formal Logic: Its Scope and Limits. 4th ed., John P. Burgess (editor), Hackett Publishing, 2006, ISBN 0872208133; ISBN 978-0872208131
- The Logic of Decision. 2nd ed. University of Chicago Press, 1990. ISBN 0-226-39582-0
- Probability and the Art of Judgment. Cambridge University Press, 1992. ISBN 0-521-39770-7
- Computability and Logic (with George BoolosGeorge BoolosGeorge Stephen Boolos was a philosopher and a mathematical logician who taught at the Massachusetts Institute of Technology.- Life :...
and John P. BurgessJohn P. BurgessJohn Burgess is a John N. Woodhull Professor of Philosophy at Princeton University. He received his Ph.D. from UC Berkeley's Group in Logic and Methodology of Science. His interests include logic, philosophy of mathematics and metaethics...
). 4th ed. Cambridge University Press, 2002. ISBN 0-521-00758-5 - Subjective Probability: The Real Thing. Cambridge University Press, 2004. ISBN 0-521-53668-5