Petrusek studied philosophy and history between 1954-1959 at Masaryk University in Brno. He wrote his thesis on "World view of Tomáš Garrigue Masaryk" and Masaryk's contribution to sociology became one of Petrusek's lifelong interests. After an obligatory army service, Petrusek became a professor of philosophy and formal logic at Pedagogical Institute in Zlín, but actively worked in sociology, a limited field in 1950s Czechoslovakia. During short time of liberalization, the Prague Spring, Petrusek earned his doctoral degree and worked at the Institute of Social-Political Sciences at Charles University. During this time, under the lead of another prominent Czech sociologist of that time, Pavel Machonin, Petrusek co-authored probably the most important work of sociology in communist Czechoslovakia till that time, "Československá společnost - Sociologická analýza sociální stratifikace", as well as "Malý sociologický slovník" for which he prepared numerous entries. Shortly after 1968 Warsaw Pact invasion of Czechoslovakia, in 1970, Petrusek was expelled from the communist party and banned by the communist regime from publishing and actively pursuing research during the whole period of normalization until the end of communism in 1989, except one book, the Introduction to Study of Sociology, a textbook published in 200 copies by Charles University. Under these circumstances, he worked within a frame of "alternative sociology", based on analysing literature as well as performing arts, which, combined with his deep knowledge of classical and contemporary sociology. He used this approach to analyse social themes in former Czechoslovak society such as gender, social stratification, problematics of higher education as well as approaching post-communist times without access to the usual tools of sociological research.
After 1989
Soon after the Velvet Revolution in 1989, Petrusek habilitated himself as a Docent of Sociology at Faculty of Philosophy, Charles University. During an attempt of dissolution of Faculty of Journalism, which was heavily controlled by communists, Petrusek persuaded the rector of the university, Radim Palouš, to attempt to transform the faculty into modern educational institution, the present Faculty of Social Sciences. Later on, Petrusek served as a dean for two terms between 1992 and 1997, after which he was one of the 10prorectors of the university in 1997–2000. During these later years of his life, Petrusek published and re-published large collection of materials that were previously released semi-officially in samizdat, as well as a number of new works both in theoretical sociology, as well as textbooks of practical sociological methods and history of sociology. One of his last monographies, "Societies of late time", contemplates the state of Czech society and strives to "answer the question in which society we live in".
