David Blackwell | |
|---|---|
.jpg) Blackwell in 1999 | |
| Born | David Harold Blackwell (1919-04-24)April 24, 1919 Centralia, Illinois, U.S. |
| Died | July 8, 2010(2010-07-08) (aged 91)[3] Berkeley, California, U.S. |
| Education | University of Illinois at Urbana-Champaign (BA,MA,PhD) |
| Known for | Rao–Blackwell theorem Blackwell channel Blackwell's contraction mapping theorem Blackwell order Arbitrarily varying channel Bayesian statistics Dirichlet distribution Games of imperfect information Mathematical economics Recursive economics Sequential analysis |
| Awards | John von Neumann Theory Prize (1979) R. A. Fisher Lectureship (1986) National Medal of Science (2012) |
| Scientific career | |
| Fields | Probability Statistics Logic Game theory Dynamic programming[1] |
| Institutions | University of California, Berkeley |
| Thesis | Some properties of Markoff chains (1941) |
| Doctoral advisor | Joseph Leo Doob[2] |
| Doctoral students | |
David Harold Blackwell (April 24, 1919 – July 8, 2010) was an Americanstatistician andmathematician who made significant contributions togame theory,probability theory,information theory, and statistics.[1] He is one of theeponyms of theRao–Blackwell theorem,[4] and is also known for theBlackwell channel,Blackwell's contraction mapping theorem, Blackwell's approachability theorem, and theBlackwell order. He wrote one of the firstBayesian statistics textbooks, his 1969Basic Statistics. He was the first African American inducted into theNational Academy of Sciences, the first African American full professor withtenure at theUniversity of California, Berkeley,[3][5][6] and theseventh African American to receive a Ph.D. in mathematics.[7] By the time he retired, he had published more than 90 papers and books ondynamic programming, game theory, and mathematical statistics.[8] In 2012,PresidentBarack Obama posthumously awarded Blackwell theNational Medal of Science.
David Harold Blackwell was born on April 24, 1919, inCentralia, Illinois, to Mabel Johnson Blackwell, a full-time homemaker, and Grover Blackwell, anIllinois Central Railroad worker.[9] He was the eldest of four children[8] with two brothers, J. W. and Joseph, and one sister, Elizabeth. Growing up in an integrated community, Blackwell attended "mixed" schools, where he distinguished himself in mathematics. During elementary school, his teachers promoted him beyond his grade level on two occasions. It was in a high school geometry course, however, that his passion for mathematics began.[10] An exceptional student, Blackwell graduated from high school in 1935 at the age of sixteen.[9]
Blackwell entered theUniversity of Illinois at Urbana-Champaign with the intent to study elementary school mathematics and become a teacher. He was a member ofAlpha Phi Alpha, a black fraternity that housed him for his full six years as a student. He earned his bachelor's degree in mathematics in three years in 1938 and, a year later, a master's degree in 1939. He was awarded aDoctor of Philosophy in mathematics in 1941[2] at the age of 22.[9][11][12] His doctoral advisor wasJoseph L. Doob. At the time, Blackwell was the seventh African American to earn a Ph.D. in mathematics in the United States and the first at the University of Illinois at Urbana-Champaign. His doctoral thesis was onMarkov chains.
Blackwell completed one year ofpostdoctoral research as a fellow at theInstitute for Advanced Study (IAS) at Princeton in 1941 after receiving aRosenwald Fellowship, which was a fund to aid black scholars.[12] There he metJohn von Neumann, who asked Blackwell to discuss his Ph.D. thesis with him.[13] Blackwell, who believed that von Neumann was just being polite and not genuinely interested in his work, did not approach him until von Neumann himself asked him again a few months later. According to Blackwell, "He (von Neumann) listened to me talk about this rather obscure subject and in ten minutes he knew more about it than I did."[14]
While a postdoc at IAS, Blackwell was prevented from attending lectures or undertaking research at nearbyPrinceton University, which the IAS has historically collaborated with in research and scholarship activities,[15] because of his race.[12]
Seeking a permanent position elsewhere, he wrote letters of application to 104historically black colleges and universities in 1942, and received a total of only three offers. He felt at the time that a black professor would be limited to teaching at black colleges.[16] Having been highly recommended by his dissertation advisorJoseph L. Doob for a position at theUniversity of California, Berkeley, he was interviewed by statisticianJerzy Neyman. Neyman supported his appointment, andGriffith C. Evans, the head of the mathematics department, at first agreed and even convinced university presidentRobert Sproul that it was the correct decision, only to subsequently balk, citing the concerns of his wife. It was customary for Evans and his wife to invite the members of the department over for dinner and "she was not going to have anydarkie in her house."[17][18]
He was offered a post atSouthern University at Baton Rouge, which he held in from 1942 to 1943, followed by a year as an Instructor atClark College in Atlanta.
Blackwell joined the Mathematics Department atHoward University in 1944. When he joined, he was one of four faculty members and within three years he was appointed full professor and head of the department.[12] He remained at Howard until 1954. In 1947, while at Howard, Blackwell published the paper "Conditional Expectation and Unbiased Sequential Estimation", which outlined a technique that later became known as theRao–Blackwell theorem.[19] Thetheorem provides a method for improving statistical estimates by potentially reducing theirmean squared error.
From 1948 to 1950, Blackwell spent his summers atRAND Corporation withMeyer Abraham Girshick and other mathematicians exploring the game theory ofduels. In 1954, Girshick and Blackwell publishedTheory of Games and Statistical Decisions.[20] Aside from von Neumann and Girshick, other Blackwell collaborators and mentors includedLeonard J. Savage,Richard E. Bellman, andNobel LaureateKenneth J. Arrow.[21]
Blackwell took a position at theUniversity of California, Berkeley as avisiting professor in 1954, and was hired as afull professor in the newly created Department of Statistics in 1955. He became the Statistics department chair in 1957.[12][22][23]
Blackwell bridgedtopology andgame theory via a game-theoretic proof ofKuratowski's coreduction principle for analytic subsets of a metric space in 1967.[24] Blackwell only briefly extended his research beyond zero-sum games to explore thesure-thing principle[25][26] as introduced byJimmie Savage,[27] primarily due the real-world societal implications of the mathematical result,[clarification needed][28] particularly for nuclear disarmament[how?] at the inception of theCold War.[29]
Blackwell wrote one of the firstBayesian textbooks, his 1969Basic Statistics. It inspired the 1995 textbookStatistics: A Bayesian Perspective by the biostatisticianDonald Berry.
He spent the rest of his career at UC Berkeley, retiring in 1988 at age 70, which at that time was the mandatory retirement age.[12][23] Over the course of his career, he mentored more than 60 students.[2]
Blackwell married Annlizabeth Madison, a 1934 graduate ofSpelman College, on December 27, 1944.[8] They had eight children together,[30] three sons and five daughters: Ann, Julia, David, Ruth, Grover, Vera, Hugo, and Sara.
David Blackwell died of complications from a stroke on July 8, 2010, atAlta Bates Summit Medical Center inBerkeley, California.[31] He was 91 years old.
In his lifetime, Blackwell received 13 honorary doctorates: eleven from American universities (the University of Illinois, Michigan State University, Southern Illinois University, Carnegie-Mellon University, Amherst College, Harvard University, Howard University, Yale University, Syracuse University, the University of Southern California, and North Carolina State University) and two from international universities (theNational University of Lesotho and theUniversity of Warwick).[37][38]
TheMathematical Association of America's MathFest, in coordination with the National Association of Mathematicians, features an annual MAA-NAM David Blackwell Lecture.[7] Blackwell offered the inaugural address in 1994; and subsequent lecturers are researchers who "exemplif[y] the spirit of Blackwell in both personal achievement and service to the mathematical community."[39]
TheBlackwell-Tapia prize is named in honor of David Blackwell andRichard A. Tapia.
The University of California, Berkeley named an undergraduate residence hall in his honor, named David Blackwell Hall. The residence hall opened in Fall 2018.[40]
An educational book about his life titledDavid Blackwell and the Deadliest Duel was published in 2019.
Blackwell made the following statement about his values and work in a 1983 interview for a project called "Mathematical People":
Basically, I'm not interested in doing research and I never have been....I'm interested in understanding, which is quite a different thing. And often to understand something you have to work it out yourself because no one else has done it.[12]
In March 2024,Nvidia announced itsBlackwellGPU architecture, named in honour of David Blackwell.[41][42]
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