quality:correction, stylistic:tone, information:extraction
Cold War politics and anticolonialism

The first period of Sartre's career, defined in large part by Being and Nothingness (1943), gave way to a second period—when the world was perceived as split into communist and capitalist blocs—of highly publicized political involvement. Sartre tended to glorify the Resistance after the war as the uncompromising expression of morality in action, and recalled that the résistants were a "band of brothers" who had enjoyed "real freedom" in a way that did not exist before nor after the war. Sartre was "merciless" in attacking anyone who had collaborated or remained passive during the German occupation; for instance, criticizing Camus for signing an appeal to spare the collaborationist writer Robert Brasillach from being executed. His 1948 play Les mains sales (Dirty Hands) in particular explored the problem of being a politically "engaged" intellectual. He embraced Marxism but did not join the Communist Party. For a time in the late 1940s, Sartre described French nationalism as "provincial" and in a 1949 essay called for a "United States of Europe". In an essay published in the June 1949 edition of the journal Politique étrangère, Sartre wrote:

If we want French civilization to survive, it must be fitted into the framework of a great European civilization. Why? I have said that civilization is the reflection on a shared situation. In Italy, in France, in Benelux, in Sweden, in Norway, in Germany, in Greece, in Austria, everywhere we find the same problems and the same dangers... But this cultural polity has prospects only as elements of a policy which defends Europe's cultural autonomy vis-à-vis America and the Soviet Union, but also its political and economic autonomy, with the aim of making Europe a single force between the blocs, not a third bloc, but an autonomous force which will refuse to allow itself to be torn into shreds between American optimism and Russian scientificism.

About the Korean War, Sartre wrote: "I have no doubt that the South Korean feudalists and the American imperialists have promoted this war. But I do not doubt either that it was begun by the North Koreans". In July 1950, Sartre wrote in Les Temps Modernes about his and de Beauvoir's attitude to the Soviet Union:

As we were neither members of the party nor its avowed sympathizers, it was not our duty to write about Soviet labor camps; we were free to remain aloof from the quarrel over the nature of this system, provided that no events of sociological significance had occurred.

Sartre held that the Soviet Union was a "revolutionary" state working for the betterment of humanity and could be criticized only for failing to live up to its own ideals, but that critics had to take in mind that the Soviet state needed to defend itself against a hostile world; by contrast Sartre held that the failures of "bourgeois" states were due to their innate shortcomings. The Swiss journalist François Bondy wrote that, based on a reading of Sartre's numerous essays, speeches and interviews "a simple basic pattern never fails to emerge: social change must be comprehensive and revolutionary" and the parties that promote the revolutionary charges "may be criticized, but only by those who completely identify themselves with its purpose, its struggle and its road to power", deeming Sartre's position to be "existentialist".

Sartre believed at this time in the moral superiority of the Eastern Bloc, arguing that this belief was necessary "to keep hope alive" and opposed any criticism of Soviet Union to the extent that Maurice Merleau-Ponty called him an "ultra-Bolshevik". Sartre's expression "workers of Billancourt must not be deprived of their hopes" (Fr. "il ne faut pas désespérer Billancourt"), became a catchphrase meaning communist activists should not tell the whole truth to the workers in order to avoid decline in their revolutionary enthusiasm.

In 1954, just after Stalin's death, Sartre visited the Soviet Union, which he stated he found a "complete freedom of criticism" while condemning the United States for sinking into "prefascism". Sartre wrote about those Soviet writers expelled from the Soviet Writers' Union "still had the opportunity of rehabilitating themselves by writing better books". Sartre's comments on Hungarian revolution of 1956 are quite representative to his frequently contradictory and changing views. On one hand, Sartre saw in Hungary a true reunification between intellectuals and workers only to criticize it for "losing socialist base".

In 1964 Sartre attacked Khrushchev's "Secret Speech" which condemned the Stalinist repressions and purges. Sartre argued that "the masses were not ready to receive the truth".

In 1969 Sartre, along with other fifteen prominent French writers, including Louis Aragon and Michel Butor, signed the letter of protest against the expulsion of "the writer most representative of the great Russian tradition, Aleksandr Solzhenitsyn - already a victim of Stalinist repression", from the Union of Soviet Writers.

In 1973 he argued that "revolutionary authority always needs to get rid of some people that threaten it, and their death is the only way". A number of people, starting from Frank Gibney in 1961, classified Sartre as a " useful idiot " due to his uncritical position.

Sartre came to admire the Polish leader Władysław Gomułka, a man who favored a "Polish road to socialism" and wanted more independence for Poland, but was loyal to the Soviet Union because of the Oder-Neisse line issue. Sartre's newspaper Les Temps Modernes devoted a number of special issues in 1957 and 1958 to Poland under Gomułka, praising him for his reforms. Bondy wrote of the notable contradiction between Sartre's "ultra Bolshevism" as he expressed admiration for the Chinese leader Mao Zedong as the man who led the oppressed masses of the Third World into revolution while also praising more moderate Communist leaders like Gomułka.

As an anti-colonialist, Sartre took a prominent role in the struggle against French rule in Algeria, and the use of torture and concentration camps by the French in Algeria. He became an eminent supporter of the FLN in the Algerian War and was one of the signatories of the Manifeste des 121. Consequently, Sartre became a domestic target of the paramilitary Organisation armée secrète (OAS), escaping two bomb attacks in the early '60s. He later argued in 1959 that each French person was responsible for the collective crimes during the Algerian War of Independence. (He had an Algerian mistress, Arlette Elkaïm, who became his adopted daughter in 1965.) He opposed U.S. involvement in the Vietnam War and, along with Bertrand Russell and others, organized a tribunal intended to expose U.S. war crimes, which became known as the Russell Tribunal in 1967.

His work after Stalin's death, the Critique de la raison dialectique (Critique of Dialectical Reason), appeared in 1960 (a second volume appearing posthumously). In the Critique Sartre set out to give Marxism a more vigorous intellectual defense than it had received until then; he ended by concluding that Marx's notion of "class" as an objective entity was fallacious. Sartre's emphasis on the humanist values in the early works of Marx led to a dispute with a leading leftist intellectual in France in the 1960s, Louis Althusser, who claimed that the ideas of the young Marx were decisively superseded by the "scientific" system of the later Marx. In the late 1950s, Sartre began to argue that the European working classes were too apolitical to carry out the revolution predicated by Marx, and influenced by Frantz Fanon started to argue it was the impoverished masses of the Third World, the "real damned of the earth", who would carry out the revolution. A major theme of Sartre's political essays in the 1960s was of his disgust with the "Americanization" of the French working class who would much rather watch American TV shows dubbed into French than agitate for a revolution.

Sartre went to Cuba in the 1960s to meet Fidel Castro and spoke with Ernesto "Che" Guevara. After Guevara's death, Sartre would declare him to be "not only an intellectual but also the most complete human being of our age" and the "era's most perfect man". Sartre would also compliment Guevara by professing that "he lived his words, spoke his own actions and his story and the story of the world ran parallel". However he stood against the persecution of gays by Castro's government, which he compared to Nazi persecution of the Jews, and said: "In Cuba there are no Jews, but there are homosexuals".

During a collective hunger strike in 1974, Sartre visited Red Army Faction member Andreas Baader in Stammheim Prison and criticized the harsh conditions of imprisonment.

Towards the end of his life, Sartre began to describe himself as a "special kind" of anarchist.