This dissertation examines Soviet and Polish science fiction from the 1960s to 1980s as a political genre that investigates power and society. The problem of alterity is central for this genre: it is ungovernable because it is incomprehensible. Science fiction of this kind explores the possibilities and impossibilities of living with the Other that can impact social organization dramatically and lethally while that Other cannot be impacted in return. Living peacefully with such alterity is the fundamental premise of pluralism as a principle of social organization, according to the conclusions of the study. The dissertation explores alterity in science fiction by Ivan Efremov (1908–1972), Arkady and Boris Strugatsky (1925–1991 and 1933–2012), Stanisław Lem (1921–2006), and Volodymyr Savchenko (1933–2005). My goal is to reveal in their works a transformative epistemological shift that had manifested itself through the tropes of alterity. Among these tropes the dissertation highlights aliens and alien civilizations, artificial intelligence, anisotropic universe, distant planets endowed with unique natural attributes, the more abstract unknown, and non-human elements running out-of-control within human species. I also examine specifically science-fictional notions such as the bull and progressor, which represent the intelligentsia’s relations with power and the masses. The analyzed literary worlds also represent their authors’ views of alternative societal organization, ruled by the powerful alterity such as a mega-computer or alien super-intelligence. Another important trope of alterity is based upon a simultaneous performance of contradictory competing logics that create an effect known as parallax: the reader may interpret the same characters and/or stories in multiple, mutually incompatible, ways. Beyond avoiding censorship, these tropes set the stage for the authors’ utopias, in which the Other appears as an impenetrable alterity that affects those who encounter it. For these writers, alterity serves as the tool for problematizing progress, as it was imagined after World War II by the majority of political elites under socialism and in the West. I suggest that their science fiction contributed, among many other factors, to the lexicon and the imaginary of a cohort of political dissidents and Communist Party functionaries alike who translated science-fictional themes into political science terms to shape Perestroika’s discourse. The dissertation, thus, establishes a historical connection between Soviet and Polish science fiction of the post-Stalin period and the ways in which democracy was discursively constructed in Russia, Ukraine, Poland, and other former socialist nations.