Stanisław Leśniewski (March 30 1886–May 13 1939) was a Polish mathematician, philosopher and logician.

Leśniewski belonged to the first generation of the Lwów-Warsaw School of logic founded by Kazimierz Twardowski. Together with Alfred Tarski and Jan Łukasiewicz, he formed the troika which made the University of Warsaw perhaps the most important research centre in the world for formal logic between the Wars. His main contribution was the construction of three nested formal systems, to which he gave the Greek-derived names of protothetic, ontology, and mereology. ("Calculus of names" is sometimes used instead of "ontology," a term widely used in metaphysics with a very different meaning.) A good textbook presentation of these systems is Simons (1987), who compares and contrasts them with the variants of mereology, more popular nowadays, descending from the calculus of individuals of Leonard and Goodman. Simons clarifies something that is very difficult to determine by reading Leśniewski and his students, namely that Polish mereology is a first order theory isomorphic to what is now called classical extensional mereology.

While he did publish a fair body of work (Leśniewski 1992 is his collected works in English translation), some of it in German, the leading language for mathematics of his day, his writings had limited impact because of their enigmatic style and highly idiosyncratic notation. Leśniewski was also a radical nominalist: he rejected axiomatic set theory at a time when that theory was in full flower. He pointed to Russell's paradox and the like in support of his rejection, and devised his three formal systems as a concrete alternative to set theory. Even though Alfred Tarski was his sole doctoral pupil, Leśniewski nevertheless strongly influenced an entire generation of Polish logicians and mathematicians via his teaching at the University of Warsaw. It is mainly thanks to the writings of his students that Leśniewski's thought is known.

Leśniewski died suddenly of cancer shortly before the German invasion of Poland, which resulted in the destruction of his Nachlass.

During the Polish-Soviet War of 1919-21, Leśniewski served the cause of Poland's independence by breaking Russian SFSR ciphers for the Polish General Staff's cryptological agency.

Writings by Leśniewski

• 1988. Lecture Notes in Logic. Kluwer. Table of Contents.
• 1992. Collected Works. 2 vols. Kluwer. Table of Contents.

• 1929, "Über Funktionen, deren Felder Gruppen mit Rücksicht auf diese Funktionen sind", Fundamenta Mathematicae XIII: 319-32.
• 1929, "Grundzüge eines neuen Systems der Grundlagen der Mathematik", Fundamenta Mathematicae XIV: 1-81.
• 1929, "Über Funktionen, deren Felde Abelsche Gruppen in bezug auf diese Funktionen sind", Fundamenta Mathematicae XIV: 242-51.

Selected secondary literature

• Ivor Grattan-Guinness, 2000. In Search of Mathematical Roots. Princeton Uni. Press.
• Luschei, Eugene, 1962. The Logical Systems of Lesniewski. North-Holland.
• Simons, Peter, 1987. Parts: A Study in Ontology. Oxford Uni. Press.
• Wolenski, Jan, 1989. Logic and Philosophy in the Lwow-Warsaw School. Kluwer.

External links

• Betti, Arianna, 2001, "Sempiternal Truth: The Bolzano-Twardowski-Lesniewski connection."
• Polish Philosophy: Stanislaw Lesniewski. By Francesco Coniglione and Arianna Betti.
• Stanford Encyclopedia of Philosophy: Lvov-Warsaw school. By Jan Woleński.
• Raul Corazzon's Formal Ontology web page: Lesniewski. Includes selected bibliography of the secondary literature.

1886 births | 1939 deaths | Polish logicians | Polish mathematicians | Polish philosophers

Stanisław Leśniewski | Stanisław Leśniewski | スタニスワフ・レシニェフスキ | Stanisław Leśniewski