Abstract: The article shows that in Marx’s texts from all periods of his work there are many categories with the existential semantics; nevertheless, they are not largely considered as significant categories in the terminological thesaurus of Marx’s thought. Such Marx’s key concepts as suffering, passion, sensuality, indifference, inhumanity, dehumanization, bestiality, enjoyment, anguish, joy of life, abomination, etc., remain beyond the analysis of his philosophy. Thus, the article raises the problem of the possibility of constructing a system of existential categories of Marx's philosophy along with a system of social and philosophical categories. The attempts made in the history of Marxist philosophy to take as the basic category of Marx’s existential philosophy such concept as alienation, embodiment, sensuality, need, lack, hardship, life, objectivity, human relationship to the world is considered. The author proposes to use the category of suffering (Leiden), which substantiates a fundamental characteristics of human existence as a human being through his/her partial (compassionate) attitude and the communication (Verkehr) with the world, as the basic concept for the construction of the system of Marx’s existential categories. Moreover, the attempt is made to develop the categorical consistency: suffering – praxis externalization (Äußerung) / assignment (Aneignung) – communication (Verkehr) – indifferent attitude to the world – inauthentic, alienated being in the world (Entäußerung, Entfremdung) –emancipation – true human being (Selbstbetätigung).
Keywords: Marx's philosophy, existential philosophy, system of philosophical categories, original category, suffering, categorical consistency.