Alfred Tarski

Alfred Tarski (, born Alfred Teitelbaum; January 14, 1901 – October 26, 1983) was a Polish-American logician and mathematician.

A prolific author best known for his work on model theory, metamathematics, and algebraic logic, he also contributed to abstract algebra, topology, geometry, measure theory, mathematical logic, set theory, and analytic philosophy.

Nevertheless, he entered the University of Warsaw in 1918 intending to study biology.

After Poland regained independence in 1918, Warsaw University came under the leadership of Jan Łukasiewicz, Stanisław Leśniewski and Wacław Sierpiński and quickly became a world-leading research institution in logic, foundational mathematics, and the philosophy of mathematics.

Leśniewski recognized Tarski's potential as a mathematician and encouraged him to abandon biology.

His thesis was entitled O wyrazie pierwotnym logistyki (On the Primitive Term of Logistic; published 1923).

Tarski and Leśniewski soon grew cool to each other, mainly due to the latter's increasing anti-semitism.

However, in later life, Tarski reserved his warmest praise for Kotarbiński, which was reciprocated.

In 1923, Alfred Teitelbaum and his brother Wacław changed their surname to "Tarski".

The Tarski brothers also converted to Roman Catholicism, Poland's dominant religion.

Alfred did so even though he was an avowed atheist.

After becoming the youngest person ever to complete a doctorate at Warsaw University, Tarski taught logic at the Polish Pedagogical Institute, mathematics and logic at the university, and served as Łukasiewicz's assistant.

Because these positions were poorly paid, Tarski also taught mathematics at a Warsaw secondary school; before World War II, it was not uncommon for European intellectuals of research caliber to teach high school.

Hence between 1923 and his departure for the United States in 1939, Tarski not only wrote several textbooks and many papers, a number of them ground-breaking, but also did so while supporting himself primarily by teaching high-school mathematics.

Henceforth Tarski attended courses taught by Łukasiewicz, Sierpiński, Stefan Mazurkiewicz and Tadeusz Kotarbiński, and in 1924 became the only person ever to complete a doctorate under Leśniewski's supervision.

In 1929 Tarski married fellow teacher Maria Witkowska, a Pole of Catholic background.

She had worked as a courier for the army in the Polish–Soviet War.

They had two children; a son Jan Tarski, who became a physicist, and a daughter Ina, who married the mathematician Andrzej Ehrenfeucht.

Tarski applied for a chair of philosophy at Lwów University, but on Bertrand Russell's recommendation it was awarded to Leon Chwistek.

In 1930, Tarski visited the University of Vienna, lectured to Karl Menger's colloquium, and met Kurt Gödel.

Thanks to a fellowship, he was able to return to Vienna during the first half of 1935 to work with Menger's research group.

From Vienna he traveled to Paris to present his ideas on truth at the first meeting of the Unity of Science movement, an outgrowth of the Vienna Circle.

Tarski's academic career in Poland was strongly and repeatedly impacted by his heritage.

For example, in 1937, Tarski applied for a chair at Poznań University but the chair was abolished to avoid assigning it to Tarski (who was undisputedly the strongest applicant) because he was a Jew.

Educated in Poland at the University of Warsaw, and a member of the Lwów–Warsaw school of logic and the Warsaw school of mathematics, he immigrated to the United States in 1939 where he became a naturalized citizen in 1945.

Tarski's ties to the Unity of Science movement likely saved his life, because they resulted in his being invited to address the Unity of Science Congress held in September 1939 at Harvard University.

Thus he left Poland in August 1939, on the last ship to sail from Poland for the United States before the German and Soviet invasion of Poland and the outbreak of World War II.

Tarski left reluctantly, because Leśniewski had died a few months before, creating a vacancy which Tarski hoped to fill.

Oblivious to the Nazi threat, he left his wife and children in Warsaw.

Once in the United States, Tarski held a number of temporary teaching and research positions: Harvard University (1939), City College of New York (1940), and thanks to a Guggenheim Fellowship, the Institute for Advanced Study in Princeton (1942), where he again met Gödel.

Tarski taught and carried out research in mathematics at the University of California, Berkeley, from 1942 until his death in 1983.

His biographers Anita Burdman Feferman and Solomon Feferman state that, "Along with his contemporary, Kurt Gödel, he changed the face of logic in the twentieth century, especially through his work on the concept of truth and the theory of models."

Alfred Tarski was born Alfred Teitelbaum (Polish spelling: "Tajtelbaum"), to parents who were Polish Jews in comfortable circumstances.

He first manifested his mathematical abilities while in secondary school, at Warsaw's Szkoła Mazowiecka.

In 1942, Tarski joined the Mathematics Department at the University of California, Berkeley, where he spent the rest of his career.

Tarski became an American citizen in 1945.

He did not see them again until 1946.

During the war, nearly all his Jewish extended family were murdered at the hands of the German occupying authorities.

Although emeritus from 1968, he taught until 1973 and supervised Ph.D. candidates until his death.

At Berkeley, Tarski acquired a reputation as an astounding and demanding teacher, a fact noted by many observers: