Growing up in a family of left-wing academics, as an adolescent Jürgen Kuczynski met numerous scholars and activists, including communist leaders Karl Liebknecht and Rosa Luxemburg.

[9] Kuczynski was advised not to eat in the student cafeteria and in his diary in 1924 he wrote he felt very keenly of "being Jewish in racial terms", going on to write: "I think I'm the only 'stranger', meaning Jew in town.

Despite his Communist sympathies, in October 1925 Kuczynski went to work at the Bett, Simon & Company bank as an intern, where he did well and was rapidly promoted up the corporate ranks.

[12] Through his parents, he became active in the League for Human Rights, a front organisation for the German Communist Party run by Willi Münzenberg who soon became a major intellectual influence on the younger Kuczynski.

[2] In 1927, his father visited the Soviet Union and was astonished to be asked if he was in any way related to the J. Kuczynski who had written the "excellent" articles on the problems of modern capitalism in the Finanzpolitische Korrespondenz.

Sources indicate that as early as February/March 1933 Kuczynski and his wife discussed following his parents and four of Jürgen's five sisters in emigrating to Britain, but they decided to stay in Germany and participate in anti-fascist resistance.

[16] Kuczynski continued to provide analytical work on economic and social developments in Germany for the benefit of Communist Party national leaderships.

[18] Within Britain his contribution to left wing politics included work on the magazine Labour Monthly, an organ of the Moscow-oriented British Communist Party.

[2] His international academic reputation gained him access to British establishment figures including, according to one source,[16] Winston Churchill, considered a political maverick, who became prime minister during the war.

[16] He maintained regular contacts with the exiled German Communist Party leadership which, during the second half of the 1930s, was based in Paris; he met with them there to exchange ideas.

[18] In the spring of 1939, he published in London The Condition of the Workers in Great Britain, Germany and the Soviet Union, 1932-1938, a comparative study of the working classes in the three nations written from a Marxist perspective.

[21] Noting the fact that theater and cinema tickets were sold cheaply in the Soviet Union, Kuczynski argued that "men do not live by bread alone.

"[21] Schulze-Fair noted that Kuzynski's bildungsbürgerlich values led him to characteristically assume that as long as works of high culture were available to the masses that must mean the lives of ordinary people were improving, making his book very naïve and dated as he completely ignored the suffering and violence of the First Five Year Plan of 1928-1933 and the Yezhovshchina (Great Purge) of 1936–38.

[3] Fuchs had already been identified by Anthony Blunt, who had sifted through the MI5 security evaluations of people involved in the Tube Alloys project (the British atomic bomb program), as someone very likely to work for Soviet intelligence if approached.

[28] In mid-1944 Kuczynski was approached by Joe Gould, a colonel in the US Office of Strategic Services, to help recruit German exiles willing to parachute into Germany for surveillance and resistance work.

(He shared these details with his sister Ursula and therefore with the Soviet Union, as described in Joseph E. Persico's Piercing the Reich: The Penetration of Nazi Germany by American Secret Agents During World War II .

[17]) Based on his recent publications on the German economy, in September 1944 Kuczynski was invited to join the Strategic Bombing Survey; he was given the rank of lieutenant-colonel in the US Army Air Force.

Kuczynski's sister Renate noted that because of his bildungsbürgerlich values that he always believed that as long as works of high culture were made available to the masses that he assumed this must mean that their characters were being improved, and for Kuyzynski the really important thing was the East German state were publishing the classics of world literature in cheap paperback copies.

Kuczynski always wrote from a Marxist perspective, but many of his writings differed significantly from the official line, for an example he sometimes criticized Vladimir Lenin, saying he had made mistakes, which was normally taboo in East Germany.

[34] Kuczynski began his argument by saying that Marxist historians must reject the "bourgeois pseudo-concept of 'objectivity'", criticizing scholars such as Leopold von Ranke and Max Weber for hiding their bias behind the façade of objectivity and concluding "...in reality, scientists cannot, did not, and must not avoid taking a stand".

[41] Even more infuriating to the East German regime, Kuczynski argued that the SPD in August 1914 was not a Leninist party, and could not had called the promised general strike to stop the war even if they had wanted to.

[40] In Neues Deutschland, the official newspaper of the SED, a harsh review of Kuczynski's book was published by Albert Schreiner, accusing him of "revisionist" beliefs and of promoting "a false view of the relationship between leftists and centrists in the workers' movement" in August 1914.

[42] In the (East) German Academy of Sciences, Kuczynski was subjected to sustained campaign by senior and junior faculty to retract his book and publicly apologize for writing it, causing him to be ostracized when he refused.

[42] On 27 February 1958, Der Ausbuch des ersten Weltkriegs und die deutsche Sozialdemokratie was in effect banned as it was announced that bookstores would no longer be allowed to sell it.

[43] In March 1958, Einheit, the official journal of the SED, published a very negative view of Der Ausbuch des ersten Weltkriegs und die deutsche Sozialdemokratie by Rudolf Lindau which accused Kuczynski of "a strange predilection" for the enemies of Marxism such as the "revisionist" Karl Kautsky, the "anarchist" Franz Pfemfert and the "Trotskyist" Paul Frölich.

[45] The fact that Kuczynski came from an upper middle-class Jewish family and had spent the Nazi years in exile in Britain instead of the Soviet Union were additional factors against him.

[45] On 2 March 1958 in a speech before the Third University Teachers' Conference with Hager being present, Kuczynski partially retracted what he had written, saying he had made mistakes, through he also expressly rejected the charge of "revisionism".

He also supported the PDS (party) (which inherited the mantle of the SED) in his writing, long after the reunification of 1989/90 had opened up the dark side of the old one-party dictatorship to wider and deeper scrutiny.

After Stalin died, his successor Nikita Khrushchev made a speech to party leaders On the Cult of Personality and Its Consequences, denouncing the abusive excesses of the regime.

[citation needed] But Kuczynski believed that "Stalinism" embraced the entire body of developments over a period of three decades, and included both positive and negative results.