Henry E. Kyburg Jr.
   HOME

TheInfoList



OR:

Henry E. Kyburg Jr. (1928–2007) was Gideon Burbank Professor of Moral Philosophy and Professor of Computer Science at the
University of Rochester The University of Rochester (U of R, UR, or U of Rochester) is a private university, private research university in Rochester, New York. The university grants Undergraduate education, undergraduate and graduate degrees, including Doctorate, do ...
, New York, and Pace Eminent Scholar at the Institute for Human and Machine Cognition, Pensacola, Florida. His first faculty posts were at Rockefeller Institute,
University of Denver The University of Denver (DU) is a private research university in Denver, Colorado. Founded in 1864, it is the oldest independent private university in the Rocky Mountain Region of the United States. It is classified among "R1: Doctoral Univ ...
,
Wesleyan College Wesleyan College is a private, liberal arts women's college in Macon, Georgia. Founded in 1836, Wesleyan was the first college in the world chartered to grant degrees to women. History The school was chartered on December 23, 1836, as the Ge ...
, and
Wayne State University Wayne State University (WSU) is a public research university in Detroit, Michigan. It is Michigan's third-largest university. Founded in 1868, Wayne State consists of 13 schools and colleges offering approximately 350 programs to nearly 25,000 ...
. Kyburg worked in probability and logic, and is known for his Lottery Paradox (1961). Kyburg also edited ''Studies in Subjective Probability'' (1964) with Howard Smokler. Because of this collection's relation to
Bayesian probability Bayesian probability is an interpretation of the concept of probability, in which, instead of frequency or propensity of some phenomenon, probability is interpreted as reasonable expectation representing a state of knowledge or as quantification ...
, Kyburg is often misunderstood to be a Bayesian. His own theory of probability is outlined in ''Logical Foundations of Statistical Inference'' (1974), a theory that first found form in his 1961 book ''Probability and the Logic of Rational Belief'' (in turn, a work closely related to his doctoral thesis). Kyburg describes his theory as Keynesian and Fisherian (see
John Maynard Keynes John Maynard Keynes, 1st Baron Keynes, ( ; 5 June 1883 – 21 April 1946), was an English economist whose ideas fundamentally changed the theory and practice of macroeconomics and the economic policies of governments. Originally trained in ...
and
Ronald Fisher Sir Ronald Aylmer Fisher (17 February 1890 – 29 July 1962) was a British polymath who was active as a mathematician, statistician, biologist, geneticist, and academic. For his work in statistics, he has been described as "a genius who ...
), a delivery on the promises of Rudolf Carnap and Hans Reichenbach for a logical probability based on reference classes, a reaction to Neyman–Pearson statistics (see
Jerzy Neyman Jerzy Neyman (April 16, 1894 – August 5, 1981; born Jerzy Spława-Neyman; ) was a Polish mathematician and statistician who spent the first part of his professional career at various institutions in Warsaw, Poland and then at University Colleg ...
, Karl Pearson, and
Neyman–Pearson lemma In statistics, the Neyman–Pearson lemma was introduced by Jerzy Neyman and Egon Pearson in a paper in 1933. The Neyman-Pearson lemma is part of the Neyman-Pearson theory of statistical testing, which introduced concepts like errors of the seco ...
), and neutral with respect to Bayesian confirmational conditionalization. On the latter subject, Kyburg had extended discussion in the literature with lifelong friend and colleague
Isaac Levi Isaac Levi (June 30, 1930 – December 25, 2018) was an American philosopher who served as the John Dewey Professor of Philosophy at Columbia University. He is noted for his work in epistemology and decision theory. Education and career Levi wa ...
. Kyburg's later major works include ''Epistemology and Inference'' (1983), a collection of essays; ''Theory and Measurement'' (1984), a response to Krantz–Luce–Suppes–Tversky's ''Foundations of Measurement''; and ''Science and Reason'' (1990), which seeks to allay Karl Popper's and
Bruno de Finetti Bruno de Finetti (13 June 1906 – 20 July 1985) was an Italian probabilist statistician and actuary, noted for the "operational subjective" conception of probability. The classic exposition of his distinctive theory is the 1937 "La prévision: ...
's concerns that empirical data could not confirm a universally quantified scientific axiom (e.g., ''F'' = ''ma''). Kyburg was Fellow of the American Association for the Advancement of Science (1982), Fellow of the American Academy of Arts and Science (1995), Fellow of the American Association for Artificial Intelligence (2002), and recipient of the Butler Medal for Philosophy in Silver from
Columbia University Columbia University (also known as Columbia, and officially as Columbia University in the City of New York) is a private research university in New York City. Established in 1754 as King's College on the grounds of Trinity Church in Manhatt ...
, where he received his PhD with
Ernest Nagel Ernest Nagel (November 16, 1901 – September 20, 1985) was an American philosopher of science. Suppes, Patrick (1999)Biographical memoir of Ernest Nagel In '' American National Biograph''y (Vol. 16, pp. 216-218). New York: Oxford University Pr ...
as his advisor. Kyburg was also a graduate of
Yale University Yale University is a Private university, private research university in New Haven, Connecticut. Established in 1701 as the Collegiate School, it is the List of Colonial Colleges, third-oldest institution of higher education in the United Sta ...
and a 1980
Guggenheim Fellow Guggenheim Fellowships are grants that have been awarded annually since by the John Simon Guggenheim Memorial Foundation to those "who have demonstrated exceptional capacity for productive scholarship or exceptional creative ability in the a ...
. Kyburg owned a farm in
Lyons, New York Lyons is a town in Wayne County, New York, United States. The population was 5,682 at the 2010 census. It is named after Lyon, France.
where he raised Angus cattle with his wife, Sarah, and promoted
wind turbine A wind turbine is a device that converts the kinetic energy of wind into electrical energy. Hundreds of thousands of large turbines, in installations known as wind farms, now generate over 650 gigawatts of power, with 60 GW added each yea ...
systems for energy-independent farmers.


Philosophical relatives

Several full professors of philosophy today were once undergraduates of Henry Kyburg, including Daniel Dennett, Robert Stalnaker, Rich Thomason, Teddy Seidenfeld, and William L. Harper. His AI dissertation students were
Ronald Loui Ronald Prescott Loui is an American computer scientist, currently working as a professor of computer science at Case Western Reserve University. He is known for having supplied first-hand biographical information on Barack Obama about his time in H ...
, Bulent Murtezaoglu, and Choh Man Teng, and postdoctoral visitor Fahiem Bacchus. His philosophy students included daughter Alice Kyburg, Mariam Thalos, Gregory Wheeler, William Harper, Abhaya Nayak, Prashanta Bandyopadhaya, in addition to those listed above.


Theory of probability

Several ideas distinguish Kyburg's ''Kyburgian'' or ''epistemological'' interpretation of probability: *Probability is measured by an interval (some mistake this as an affinity to Dempster–Shafer theory, but Kyburg firmly rejects their rule of combination; his work remained closer to confidence intervals, and was often interpreted by Bayesians as a commitment to a set of distributions, which Kyburg did not repudiate) *All probability statements can be traced to direct inference of frequency in a reference class (there can be Bayes-rule calculations upon direct-inference conclusions, but there is nothing like a prior distribution in Kyburg's theory) *The reference class is the most specific class with suitable frequency knowledge (this is the Reichenbach rule, which Kyburg made precise; his framework was later reinterpreted as a
defeasible reasoning In philosophical logic, defeasible reasoning is a kind of reasoning that is rationally compelling, though not deductive reasoning, deductively valid. It usually occurs when a rule is given, but there may be specific exceptions to the rule, or su ...
system by John L. Pollock, but Kyburg never intended the calculation of objective probabilities to be shortcut by bounded rationality due to computational imperfection) *All probability inferences are based on knowledge of frequencies and properties, not ignorance of frequencies; however, randomness is essentially the lack of knowledge of bias (Kyburg especially rejects the maximum entropist methods of
Harold Jeffreys Sir Harold Jeffreys, FRS (22 April 1891 – 18 March 1989) was a British mathematician, statistician, geophysicist, and astronomer. His book, ''Theory of Probability'', which was first published in 1939, played an important role in the revival ...
, E.T. Jaynes and other uses of the
Principle of Indifference The principle of indifference (also called principle of insufficient reason) is a rule for assigning epistemic probabilities. The principle of indifference states that in the absence of any relevant evidence, agents should distribute their cre ...
here; and Kyburg disagrees here with
Isaac Levi Isaac Levi (June 30, 1930 – December 25, 2018) was an American philosopher who served as the John Dewey Professor of Philosophy at Columbia University. He is noted for his work in epistemology and decision theory. Education and career Levi wa ...
who believes that chance must be positively asserted upon knowledge of relevant physical symmetries) *There is no disagreement over the probability once there is agreement on the relevant knowledge; this is an objectivism relativized to an evidential state (i.e., relativized to a set of observed frequencies of properties in a class, and a set of asserted properties of events) Example: Suppose a ''corpus of Knowledge'' at a ''level of acceptance.'' Contained in this corpus are statements, ''e is a T1'' and ''e is a T2''. The observed ''frequency of P among T1'' is .9. The observed ''frequency of P among T2'' is .4. What is the ''probability that e is a P''? Here, there are two ''conflicting reference classes,'' so the probability is either ''
, 1 The comma is a punctuation mark that appears in several variants in different languages. It has the same shape as an apostrophe or single closing quotation mark () in many typefaces, but it differs from them in being placed on the baseline o ...
', or some interval combining the .4 and .9, which sometimes is just '' 4, .9' (but often a different conclusion will be warranted). Adding the knowledge ''All T1's are T2's'' now makes T1 the ''most specific relevant reference class'' and a ''dominator'' of all ''interfering reference classes.'' With this universal statement of class inclusion, the probability is 9, .9 by ''direct inference from T1''. Kyburg's rules apply to conflict and subsumption in complicated partial orders.


Acceptance and principles of rational belief

Kyburg's inferences are always relativized to a ''level of acceptance'' that defines a corpus of ''morally certain'' statements. This is like a level of confidence, except that Neyman–Pearson theory is prohibited from retrospective calculation and post-observational acceptance, while Kyburg's epistemological interpretation of probability licenses both. At a level of acceptance, any statement that is more probable than the level of acceptance can be adopted as if it were a certainty. This can create logical inconsistency, which Kyburg illustrated in his famous lottery paradox. In the example above, the calculation that ''e is a P'' with probability .9 permits the ''acceptance'' of the statement ''e is a P'' categorically, at any level of acceptance lower than .9 (assuming also that the calculation was performed at an acceptance level above .9). The interesting tension is that very high levels of acceptance contain few evidentiary statements. They do not even include ''raw observations of the senses'' if those senses have often been fooled in the past. Similarly, if a measurement device reports within an interval of error at a rate of .95, then no measurable statements are acceptable at a level above .95, unless the interval of error is widened. Meanwhile, at lower levels of acceptance, so many contradictory statements are acceptable that nothing useful can be derived without inconsistency. Kyburg's treatment of universally quantified sentences is to add them to the ''Ur-corpus'' or '' meaning postulates'' of the language. There, a statement like ''F = ma'' or ''preference is transitive'' provides additional inferences at all acceptance levels. In some cases, the addition of an axiom produces predictions that are not refuted by experience. These are the adoptable theoretical postulates (and they must still be ordered by some kind of simplicity). In other cases, the theoretical postulate is in conflict with the evidence and measurement-based observations, so the postulate must be rejected. In this way, Kyburg provides a probability-mediated model of
predictive power The concept of predictive power, the power of a scientific theory to generate testable predictions, differs from '' explanatory power'' and ''descriptive power'' (where phenomena that are already known are retrospectively explained or describe ...
, scientific theory-formation, the ''Web of Belief'', and linguistic variation. The theory of acceptance mediates the tension between linguistic categorical assertion and probability-based epistemology.


References


External links


Official Obituary
{{DEFAULTSORT:Kyburg 20th-century American philosophers 1928 births 2007 deaths University of Rochester faculty Wayne State University faculty University of Denver faculty Columbia University alumni Yale University alumni