Born Alfred Tajtelbaum in 1901, to a Jewish-Polish family in Warsaw, he changed his name, along with his brother, to Tarski in 1923.
He was the only person to complete a doctoral thesis under Stanisław Leśniewski and was also, at the time, the youngest ever PHD graduate from Warsaw University.
Besides Leśniewski, he came under the influence of other members of the Lviv-Warsaw school, including Tadeusz Kotarbiński and Jan Łukasiewicz.
Tarski made considerable contributions to a wide range of subjects at the intersection of mathematics, logic and philosophy, including: topology, geometry, mathematical logic, model theory, algebraic logic, metamathematics and the philosophy of logic and language.
He is perhaps most well known for his work on truth which was, among other things, an attempt to deal with the paradoxes that had fascinated and troubled mathematicians and philosophers for centuries. A simple example is the "Liar Paradox": if someone says, "I am lying" then if they are lying they are telling the truth, but if they are telling the truth - they are lying.
Tarski sought to solve this kind of paradox by distinguishing languages from metalanguages. Sometimes we are saying something about the world (in a language), but sometimes we are saying something about that language itself (in a metalanguage). Paradoxes appear when we do not distinguish these "levels".
Paradoxically (!), it was Bertrand Russell, one of the key discoverers of paradoxes, who denied Tarski his nomination to a chair of mathematics at Lviv University.
Tarski travelled to the United States in 1939 to a conference in Harvard, by great fortune on the last ship from Poland to the US before the German and Russian invasions.
Tarski joined the Mathematics Department at Berkeley in 1942, becoming a US citizen in 1945. Even as an emeritus he supervised PHD students at Berkeley, until his death in 1983.
Sources: polskieradio.pl, Stanford Encyclopedia of Philosophy
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