Fredrik entered the room looking a little paler than usual, a little tense after the hours of hard work on the political articles. The work had taken much more out of him than all his scholarly papers. He was no politician, had never been much interested in politics. When the Left Party Venstre said one thing and the Right another that was probably just the way it had to be, but what the Right said was correct, he felt it faintly, deep down inside, though he used to say that there was a lot in what the opposition Left Party had to say. (Editor Lynge, 1893)
Hamsun was an enthusiastic debater and polemicist.
As early as 1889 he published a series of articles critical of the priest, politician and newspaperman Lars Oftedal. In 1902 Hamsun opposed Bjørnstjerne Bjørnson, whom he otherwise held in the highest regard, when Bjørnson publicly have his support to the Union Party. In 1915 Hamsun participated in the extensive debate known as the "Child-killer debate". Sigrid Undset implied that the reason and remedy for the increase in the number of infants being killed was a social matter. Hamsun, on the other hand, recommended draconian sentencing. In 1936 Hamsun involved himself in a debate over whether or not the Jewish Carl von Ozzietsky deserved his award of the Nobel Peace Prize, and during the war he wrote a number of political articles in support of Germany. Some of this material was used in evidence against him at his trial for treason.
There are traces of his political involvement in a number of novels. The novel Shallow Soil (1893) describes the spit in the Left Party. "The "Child-killer debate” is echoed in Growth of the Soil (1917) in the description of Inger and Barbro’s crimes.