Meaning of natural deduction in English:

natural deduction

noun

Logic
  • A method, devised separately in 1934 by G. Gentzen (Math. Zeitschr. (1935) 39) and S. Jaśkowski (Studia Logica (1934) 1), whereby formal proofs are obtained solely by the application of rules of inference without appeal to axioms.

Origin

1940s; earliest use found in Journal of Symbolic Logic.