He is mainly remembered for his biographies of notable thinkers of Western philosophy.
He was the son of Oscar Svendsen (1876–1967), and his wife, Dagmar Marie Steffensen (born 1882).
In 1940, he defended a thesis titled Gullalderdrøm og utviklingstro, which earned him a dr.philos.
He was hired as a senior lecturer in comparative literature at the University of Oslo in 1946.
He wrote biographies on Dutch philosopher Erasmus, Danish philosopher and theologian Søren Kierkegaard, Norwegian short story writer and novelist Maurits Hansen and Norwegian poet Conrad Nicolai Schwach.