Prawitz, Proofs, and Meaning

Normality, Non-contamination and Logical Depth in Classical Natural Deduction

“…Ian Von Plato has recently discovered that, in fact, Gentzen had a proof also for his natural deduction system NJ that he decided not to publish[von Plato, 2008] probably because he despaired to show a similar result for classical logic. For an excellent overview of Prawitz's work in proof theory see[Wansing, 2015].3 In fact, for this purpose the Jaśkoswski-Fitch presentation of proofs is much more popular than the original Gentzen-Prawitz presentation which, on the other hand, is dominant in proof-theoretical studies. For a comparison seeHazen, 2012, Hazen andPelletier, 2014].4 For insightful and comprehensive treatments see[Tennant, 1990, Negri andvon Plato, 2001]).…”