### Life and achievements

##### Early life

Alfred Tarski was born in Warsaw, Poland, in 1901 to a Jewish family during political turbulence and the transformation of European states. Tarski's family was not very poor, and he was able to attend Warsaw's prestigious Szkoła Mazowiecka, where he began to show interest in mathematics. Although he had wanted to study biology at first, the academic climate at the University of Warsaw, especially with Jan Łukasiewicz and Stanisław Leśniewski, influenced him to take up mathematics and logic.

Tarski and his brother adopted the new surname Tarski in 1923, which was not uncommon for Polish Jews who wanted to be accepted by society. At the same time, he converted to Catholicism, but he was an atheist throughout his life. He had a brilliant academic record at Warsaw, where he did his doctorate under the guidance of Leśniewski. His initial academic experience was in the **Lwów–Warsaw school of logic**, which significantly influenced his formative years.

Tarski was able to work with other prominent logicians and mathematicians during his time in Warsaw, and his early works show his deep interest in formal logic. However, due to the increasing anti-Semitism in Poland, he often could not secure a job in academia and had to look for work abroad.

##### Legacy

Alfred Tarski is one of the most influential mathematicians of the twentieth century, whose contributions span several disciplines. One of his most important contributions is his definition of truth through the creation of **Convention T**. This work provided the basis for contemporary semantic theory and changed the perception of truth in formal languages. His contributions to model theory and set theory are still felt in these areas of study to this day.

Besides his theoretical contributions, Tarski's teaching experience at the University of California, Berkeley, produced a new generation of logicians and mathematicians. He was a man of outstanding commitment to the principles of accuracy, simplicity, and critical thinking in teaching, which made his seminars very popular but also very demanding. Tarski's support for women in mathematics, mainly because the field was not welcoming of women at the time, was another aspect of his progressive thinking regarding education.

Tarski's work is also reflected in his co-authored works, especially the **Banach-Tarski paradox**, which demonstrated the implications of set theory. Although this may seem paradoxical at first, it became one of the basic principles of modern mathematics, showing the peculiarities of the theory of infinite sets.

Today, Tarski is considered one of the leading logicians of the twentieth century and is compared to Kurt Gödel. He contributed immensely to the philosophy of language, logic, and mathematics, placing him among the most critical thinkers of the twentieth century.

### Milestone moments

## Jan 28, 1924

**Completion of Doctorate**Alfred Tarski received his doctorate at the University of Warsaw, in January 1924, and he was the youngest person to do so.

His dissertation, written under the guidance of Stanisław Leśniewski and titled "On the Primitive Term of Logistic," is considered a starting point for Tarski's further research in the field.

Tarski's doctoral thesis proved he was an outstanding specialist in formal systems and logical structure.

Although Tarski and Leśniewski had a somewhat tense relationship in the later years due to differences in personality and ideas, this initial association played a significant role in forming Tarski's academic thinking.

## Sep 28, 1939

**Coming to the United States of America**Tarski came to the United States in September 1939, at the onset of World War II in Europe.

He was supposed to give a lecture at Harvard, and the fact that he was in the process of traveling to that university proved to be a lifesaver.

Tarski stayed in the U.S. while his family was exposed to the genocide in Poland during the Holocaust.

This marked a new chapter in Tarski's life, as he easily adapted to the American system of higher learning.

It also enabled him to avoid the increasing anti-Semitism and the war in Europe and carry on his research in a more peaceful environment.

## Dec 28, 1945

**Convention T and the Semantic Theory of Truth**In the mid-1940s, Tarski completed his work on the semantic theory of truth, encapsulated in what is now known as 'Convention T.'

This theory provided a formal approach to truth in formal languages by distinguishing between the object language and meta-language.

When published, this work significantly influenced the philosophy of language and logic.

Convention T addressed critical issues concerning the nature of paradoxes and became the primary reference source in discussions on truth and formal logic.

## Mar 28, 1949

**The Banach–Tarski Paradox**In 1949, Tarski and his colleague Stefan Banach devised the Banach-Tarski paradox.

This result, which stated that a sphere could be cut into a finite number of pieces and then reassembled to form two spheres of the same size, surprised the mathematical community.

The paradox demonstrated the counterintuitive implications of set theory and the Axiom of Choice.

It became one of the most popular results in modern mathematics, illustrating the complexities of infinity and its unexpected behavior.