Results in the
Arithmetization of Logical Systems

Aristotle + Leibniz

This collage represents both great logicians: Aristotle (384-322 BC), the creator of the Science of Logic, and Gottfried Wilhelm von Leibniz (1646-1716), the first who transmuted it into a mathematical discipline. They are pronouncing two winged phrases. Magister dixit ("The Master said it") is the scholastic conjuration reducing any proof to Aristotle's authority (of course, he was not implicated in the mediaeval speculations with his name). On the contrary, Calculemus! ("Let's calculate!") reflects Leibniz's conviction that all human reasoning may be turned into an object of mathematical demonstration and in such a way, any controversal truth can obtain the evidence of 2+2=4.
 
 

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A detailed history of Leibniz's ideas together with full proofs see in my paper published in the Special Issue of the Journal of Applied Non-Classical Logics (v. 9, no. 2-3/1999, pp. 387-405) dedicated to the memory of my colleague and friend George Gargov (1947-1996):

Arithmetizations of Syllogistic à la Leibniz

Leibniz's arithmetical translation was extended on the logic of properties in the contributed paper presented at the Logic Colloquium '99 (Utrecht, August 1-6, 1999):

Monadic Predicate Calculus Arithmetized
à la Leibniz

Further on, the arithmetical translation involved equality as well. The text containing full demonstrations see in Comptes Rendues de l'Académie bulgare des Sciences (v. 54, no. 1, 2001, pp. 9-10):

Monadic Predicate Calculus with Equality
Arithmetized à la Leibniz

Different syllogistics were uniformly considered in the contributed paper presented at the 2nd Panhellenic Logic Symposium (Delphi, Greece, July 13 - 17, 1999: Proceedings, pp. 197-200):

Various Syllogistics from the Algebraic
Point of View

A popular exposé of Leibniz's programme together with my own results in its realization (in Bilgarian) see in the report presented at the 29th Spring Conference of the Union of the Bulgarian Mathematicians (Lovetch, April 3-6, 2000: Proceedings, pp. 36-45):

The Leibniz Programme:
Calculation in Lieu of Disputation

In 1999, the next volume of Leibniz's philosophical heritage appeared  after a 20-year wait. It was prepared by Leibniz-Forschungsstelle in Münster and included the logical manuscripts of Leibniz written between 1677 and 1690. Fortunately they are accessible nowadays from the Internet: you can download the full Band VI-4 of his Philosophische Schriften and especially the PDF-file (2 MB) containing the most interesting for us manuscripts. My Essay Review on this edition was published in History and Philosophy of Logic (v. 22, 2001, n. 3, pp. 164-168). You can find there a contemporary view on Leibniz's logical ideas, a critical exposition of his philosophical dreams, and a reconstruction of his logical systems:

Essay Review

"Scholastic" arithmetical semantics: mode d'emploi. Namely, one of both Leibniz's models was tested on some simple examples in my paper announced on the 8th International Leibniz Congress (Hanover, July 2006). Note that the negation of a notion in this model is impossible when the universe of notions is infinite. Is any philosophical peculiarity of our thinking hidden in this phenomenon?

Leibniz's "Calculemus!" at Work

Leibnizian arithmetical semantics: mode d'emploi. Leibniz's preferable model was tested and compared with the "Scholastic" arithmetical semantics in the report presented on the 9th International Leibniz Congress (Hanover, September 2011). Boolean algebra of the 8 fundamental colours is another elegant illustration of the intensional semantics at work and this Easter egg is its picturesque visualization.

Leibniz's Intensional Semantics of Syllogistics 

(a Reconstruction)

 

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Acknowledgement

Many people helped my investigations in this field. I am grateful to the former Director of Leibniz-Forschungsstelle in Münster Prof. Hans Schepers, to Prof. Martin Schneider, and to Dr. Herma Kliege-Biller for their consultations, for the opportunity to touch some Leibniz's manuscripts interesting for me, and for assigning me the extremely valuable edition of Leibniz's writings. Due to the hospitality of Prof. Wolfgang Lenzen from Osnabrück I obtained an access to the literature lacking in Bulgaria. Prof. Hans Poser and his colleagues from the Technical University in Berlin made possible my visit to the 7th Leibniz-Kongress in 2001. The invitation from Prof. Hiroakura Ono and the grant from the Japan Society for the Promotion of Science (JSPS) assured my one-month stay in 1999 at the Japan Advanced Institute of Science and Technology (JAIST) in Hokuriku near Kanazawa. In 2003 I visited JAIST for the second time thanks to a grant from JSPS as well as Kyoto University thanks the the invitation from Prof. Soshichi Uchii. Prof. Herbert Breger and his colleagues from the University of Hanover assured my participation in the 8th Leibniz-Kongress in 2006 and in the next Kongress in 2012 as well. My last results are a part of a joint project with Prof. W. Lenzen and have been supported by grant LE 510/17-1 (2010-2011) from Deutsche Forschungsgemeinschaft.