Career
He was a professor at the University of Oslo from 1952 to 1975, he specialized in political history and the history of ideas. Seip"s use of the Norwegian language and his writing style which numerous historians have described as brilliant, and often tried emulating. Seip was included among the 16 authors of " The Norwegian literary canon" from 1900 to 1960 and 2nd among 20 authors in a ranking of nonfiction writers conducted by Dagbladet in 2008.
Seip received an honorary doctorate at the University of Bergen from 1975.
He graduated as candidate.philol. in 1931. He worked as a research fellow at the University of Oslo from 1936, under the tutorship of Edvard Bulletin, and became known for the journal article Problemer og metode i norsk middelalderforskning in 1940.
He then worked for the National Archival Services of Norway from 1941. Jens Arup Seip completed his thesis Sættargjerden i Tunsberg og kirkens jurisdiksjon in 1942, but did not receive the dr.philos. degree until 1945.
He worked as a lecturer in history from 1946, and was also a consultant at the Norwegian Nobel Institute from 1946 to 1958.
From 1955 to 1966 he chaired the Norwegian Historical Association. In 1952 he was promoted to the position of professor In addition, he drifted from his former specialty in medieval history to political history and the history of ideas.
Among his most important publications were Fra embedsmannsstat til ettpartistat (1963) and Utsikt over Norges historie in two volumes (1974 and 1981).
Many of his terms have entered the Norwegian historio-political lexicon.