Spurred on by a series of seminars in Poland in 1926 by Łukasiewicz that advocated a more natural treatment of logic, Jaśkowski made the earliest attempts at defining a more natural deduction. In 1929 he first suggested in 1929 using a diagrammatic notation, and later updated his proposal in papers in 1934 and 1935.
References[change | change source]
- Jaśkowski, Stanaslaw 1934. On the rules of suppositions in formal logic.
- Jon Barwise and John Etchemendy, 2000. Language, proof and logic. CSLI (University of Chicago Press) and New York: Seven Bridges Press. A gentle introduction to first-order logic via natural deduction, by two first rate logicians.
Other websites[change | change source]
- Clemente, Daniel, "Introduction to natural deduction."
- Pelletier, Jeff, "A history of natural deduction and elementary logic textbooks."