Bruno von Freytag-Löringhoff
# Bruno von Freytag-Löringhoff

Bruno Baron von Freytag-Löringhoff (11 June 1912–28 February 1996) was a German philosopher, mathematician and epistemologist. He was also a university lecturer at the University of Tübingen. During World War II, Freytag-Löringhoff worked as a mathematician in the In 7/VI, that was the signals intelligence agency of the Wehrmacht and worked with Fritz Menzer on the testing of cryptographic devices and procedures. Freytag-Löringhoff worked specifically on the testing of the m-40 cipher machine. His most important contributions to the history of logic and mathematics was his studies and descriptions from 1957, of the calculating machine, built by Wilhelm Schickard.

Bruno von Freytag-Löringhoff was an aristocrat and a member of the noble house of Frydag.

## Life

After attending lectures in mathematics, physics, musicology and philosophy at the Universities of Greifswald and Munich, Freytag earned his doctorate in Philosophy in Greifswald in 1936 and habilitated in 1944 in Freiburg im Breisgau and 1947 in Tübingen after taking part in the war. From 1955, Freytag-Löringhoff was Professor of Philosophy at the University of Tübingen. In 1957 he reconstructed the first calculating machine of 1623, which was handed down only in scanty sketches from the Tübingen astronomy professor Wilhelm Schickard. He also built the data sticks from Schickard. After his retirement in 1977 Freytag studied the structures of the still new PCs.

## Works

During the Third German Congress of Philosophy in October 1950, Freytag-Löringhoff presented a series of theses to the Symposium, where he argued that the various logical systems were not pure but that each of them includes a pure kernel that could be identified, and separated out. The kernel could be considered pure philosophical logic, i.e. logic tout court which is characterised by its properties, that is identity, contradiction and their interweaving (German: Verflechtung). Although there were many logical calculi, he considered pure logic to be unique and that diverse logical systems are mathematical systems that must be interpreted with the aid of pure logic. For Freytag-Löringhoff:

    mathematics presupposes logic and cannot found it

Logical calculi begin from elements which require analysis through pure logic. He considered the most fundamental element in logistic is judgment (German: Urteil), the most fundamental element in logic is concept, (German: Begriff). Pure philosophical logic is a closed, self-contained, system, without fundamental flaws and of great beauty and wide applicability, and attacks against classical logic are largely unjustified. Freytag-Löringhoff was a staunch proponent of Aristotelian logic. His views were challenged by Józef Maria Bocheński, Paul Bernays and Béla Juhos, who were also at the Symposium. Haskell Curry constructed a logical model that he used to contest Freytag-Löringhoff theses.

His most important contribution to logic was the study, that started in 1979, of the calculating machine of Wilhelm Schickard. During his lifetime, he constructed several models, one of which he kept at his home with the help of mechanic, Erwin Epple.

