Klas Pontus Arnoldson (October 27, 1844-February 20, 1916), the Swedish journalist, pacifist, and proponent of Scandinavian unity, was a man of humble origin. Born at Goteborg, the son of a caretaker, he was obliged to discontinue his formal education in the public schools of Goteborg at the age of sixteen because of family financial difficulties after the death of his father in 1860. For the next twenty-one years he worked for a railroad, first as a clerk and then for ten years as a station inspector in Jonsered, Algaras, and Tumba.

During these years, Arnoldson continued his studies, reading widely in history, religion, and philosophy; observed the political events of his day, especially the Danish-Austrian-Prussian War of 1864 and the Franco-Prussian War of 1870-1871; and evolved the ideas on religion, politics, and peace that he developed in detail in his voluminous writings.

Arnoldson was a liberal in theology. Familiar with the humanistic tenets of religious movements originating in the nineteenth century in Great Britain and in the New England section of the United States, he decried fanatic dogmatism and espoused essentially Unitarian views on truth, tolerance, freedom of the individual conscience, freedom of thought, and human perfectability. These views he published in the Nordiska Dagbladet [Northern Daily] which he edited for a short time in the early 1870's, and in Sanningssokaren [The Truth Seeker], a monthly journal devoted to the exposition of «practical Christianity», as well as in books and pamphlets.

Arnoldson was also a liberal in political philosophy, committed to the practical application of the principle of democracy and individualism. From 1882 to 1887, as an elected member of the Parliament, he introduced legislation to extend the franchise and when it failed to pass, supported legislation which later succeeded; favored the extension of religious freedom; pursued an antimilitaristic policy; drafted a controversial resolution asking the government to investigate the possibility of guaranteed neutrality for Sweden.

Outside Parliament Arnoldson carried on work for peace even more vigorously. Originally attracted to pacifism because of his repugnance for the wars of 1864 and 1870-1871 and because of his religious beliefs, Arnoldson was one of those instrumental in founding the Swedish Peace and Arbitration Association in 1883, occupying the position of secretary of the society and becoming the editor of Tiden [The Times], a medium for peace information and free debate. Not at his best in a managerial capacity, Arnoldson resigned from Tiden in 1885 when it ran into financial difficulties, and from his office with the peace society in 1887 when he felt himself being overwhelmed by financial problems, the pressure of work, and emotional depression. Arnoldson edited Fredsvannen [The Friend of Peace] from 1885 to 1888 and the Nordsvenska Dagbladet [North Sweden Daily] from 1892 to 1894. For the most part, however, he kept himself free of administrative and political duties, devoting his energies to speaking and writing on behalf of arbitration. In 1888 he mounted a campaign for a popular petition addressed to the king favoring arbitration agreements with foreign nations. Extending his agitation to Norway in 1890, he spoke to receptive audiences throughout the country and provided some of the impetus for the Norwegian Parliament's passage of a resolution on arbitration addressed to the king.

In the political controversy of 1895 between Norway and Sweden and in the final constitutional crisis which resulted in dissolution of their Union, Arnoldson sympathized with Norway. This was not popular in Sweden. When Arnoldson was named a Nobel peace laureate in 1908, some Swedish newpapers were incensed, saying that the award was an «outrage» against Sweden, a disgrace to «every Swedish man who takes pride in his national honor», and, to add injury to insult, was paid for with «Swedish money» given by a Swedish countryman. In reply, Lovland, chairman of the Norwegian Nobel Committee, pointed out that Arnoldson's candidacy had been proposed by the unanimous vote of the Swedish Group of the Interparliamentary Union.

Throughout his life, Arnoldson complemented his day-to-day political activity by writing. In his early years he wrote mainly journalistic pieces; in the last three decades of his life, he produced some major works. An historical essay on international law, Ar varldsfred mojlig? [Is World Peace Possible? translated into English under the title of Pax mundi], appeared in 1890; Religionen i forskningens ljus [Religion in the Light of Research] in 1891; a history of the pacifist idea, Seklernas hopp [The Hope of the Centuries], in 1901. He also wrote polemical fiction, putting his pacifist message into novelistic and dramatistic form.

Although Arnoldson suffered from periods of illness throughout his life, he lived to be seventy-two, dying of a heart attack in Stockholm in 1916.