1001Philosophers

Stanislaw Lesniewski 1886 – 1939

Stanislaw Lesniewski was a Polish logician, philosopher of mathematics, and the most uncompromising formalist of the Lwow-Warsaw school. After studies under Kazimierz Twardowski at Lwow and a doctorate under Hans Cornelius at Munich, he held the chair of the philosophy of mathematics at Warsaw, where he developed his three interrelated formal systems: Mereology, the logic of parts and wholes; Ontology, his general theory of names and predication; and Protothetic, a comprehensive logic of propositions and quantifiers. The extreme rigor of his standards meant that much of his work survives only through his pupils, above all Alfred Tarski.

Key facts

Nationality
Polish
Era
Contemporary
Movements
Analytic

Selected quotes

  • Attributed to Stanislaw Lesniewski:

    “Logic must rest on principles whose evidence we cannot doubt.”

  • Attributed to Stanislaw Lesniewski:

    “A class is the whole of its members, not a thing apart.”

  • Attributed to Stanislaw Lesniewski:

    “Definition must be eliminable without loss.”

  • Attributed to Stanislaw Lesniewski:

    “Formal systems are the precise instruments of philosophical thought.”

  • Attributed to Stanislaw Lesniewski:

    “What can be said clearly must first be axiomatized.”