Stanisław Jaśkowski (22 April 1906, in

Warsaw Warsaw ( pl, Warszawa, ), officially the Capital City of Warsaw,, abbreviation: ''m.st. Warszawa'' is the capital and largest city of Poland. The metropolis stands on the River Vistula in east-central Poland, and its population is officia ...

– 16 November 1965, in Warsaw) was a Polish

logician Logic is the study of correct reasoning. It includes both formal and informal logic. Formal logic is the science of deductively valid inferences or of logical truths. It is a formal science investigating how conclusions follow from premises ...

who made important contributions to proof theory and formal semantics. He was a student of

Jan Łukasiewicz Jan Łukasiewicz (; 21 December 1878 – 13 February 1956) was a Polish logician and philosopher who is best known for Polish notation and Łukasiewicz logic His work centred on philosophical logic, mathematical logic and history of logic. ...

and a member of the Lwów–Warsaw School of Logic. Upon his death his name was added to the Genius Wall of Fame. He was the President (rector) of the Nicolaus Copernicus University in

Toruń )'' , image_skyline = , image_caption = , image_flag = POL Toruń flag.svg , image_shield = POL Toruń COA.svg , nickname = City of Angels, Gingerbread city, Copernicus Town , pushpin_map = Kuyavian-Pom ...

. Jaśkowski is considered to be one of the founders of

natural deduction In logic and proof theory, natural deduction is a kind of proof calculus in which logical reasoning is expressed by inference rules closely related to the "natural" way of reasoning. This contrasts with Hilbert-style systems, which instead use ax ...

, which he discovered independently of

Gerhard Gentzen Gerhard Karl Erich Gentzen (24 November 1909 – 4 August 1945) was a German mathematician and logician. He made major contributions to the foundations of mathematics, proof theory, especially on natural deduction and sequent calculus. He died ...

in the 1930s. Gentzen's approach initially became more popular with logicians because it could be used to prove the

cut-elimination theorem The cut-elimination theorem (or Gentzen's ''Hauptsatz'') is the central result establishing the significance of the sequent calculus. It was originally proved by Gerhard Gentzen in his landmark 1934 paper "Investigations in Logical Deduction" for ...

. However, Jaśkowski's is closer to the way that proofs are done in practice. He was also one of the first to propose a formal calculus of inconsistency-tolerant (or paraconsistent) logic. Furthermore, Jaśkowski was a pioneer in the investigation of both

intuitionistic logic Intuitionistic logic, sometimes more generally called constructive logic, refers to systems of symbolic logic that differ from the systems used for classical logic by more closely mirroring the notion of constructive proof. In particular, systems ...

and free logic.

Works

''On the Rules of Suppositions in Formal Logic''
Studia Logica 1, 1934 pp. 5–32 (reprinted in: Storrs McCall (ed.), ''Polish Logic 1920-1939'', Oxford University Press, 1967 pp. 232–258 * ''Investigations into the System of Intuitionist Logic'' 1936 (translated in: Storrs McCall (ed.), ''Polish Logic 1920-1939'', Oxford University Press, 1967 pp. 259–263 * ''A propositional Calculus for Inconsistent Deductive Systems'' 1948 (reprinted in: Studia Logica, 24 1969, pp 143–157 and in: Logic and Logical Philosophy 7, 1999 pp. 35–56) * ''On the Discussive Conjunction in the Propositional Calculus for Inconsistent Deductive Systems'' 1949 (reprinted in: Logic and Logical Philosophy 7, 1999 pp. 57–59) * ''On Formulas in which no Individual Variable occurs more than Twice'', Journal of Symbolic Logic, 31, 1966, pp. 1–6) ; in Polish: * ''O symetrii w zdobnictwie i przyrodzie - matematyczna teoria ornamentów'' (English title: ''On Symmetry in Art and Nature''), PWS, Warszawa, 1952 (book 168 pages) * ''Matematyczna teoria ornamentów'' (English title: ''Mathematical Theory of Ornaments''), PWN, Warszawa, 1957 (book 100 pages)

References

* * * Jerzy Kotas, August Pieczkowski. ''Scientific works of Stanisław Jaśkowski'', Studia Logica 21, 1967, 7-15

External links

1906 births 1965 deaths Writers from Warsaw Polish logicians Polish mathematicians University of Warsaw alumni Nicolaus Copernicus University in Toruń faculty Paraconsistent logic 20th-century Polish philosophers {{Poland-philosopher-stub