Many conflicting debates on the application of the principle of mass strike (Massenstreik) in the German Social Democratic Party (SPD) bear witness to the slow agony of Marxist ideals within the mass party. From the fragile victory of the ideals advocated by the radical faction of the party against those of the reformers, between 1900 and 1906, the return of the pendulum after the first Russian revolution was merciless. Between 1906 and 1910, in the eyes of the leaders of the party, legal-parliamentary logics progressively became the only legitimate way to go. This change in tactics and strategy to gain power, was fiercely challenged by several influential party activists. The intellectual conflict between Rosa Luxemburg and Karl Kautsky, that broke out publicly in 1910 while the protest movements in Germany were very strong, allows us to understand, through a discourse analysis of these Marxist thinkers, the reasons that led the SPD to not apply the mass strike, even though the principle had been voted in during the 1905 Jena Congress. Based on her pseudo-serendipity outlook, Luxemburg firmly believed that the time was favorable for implementing the mass strike. Kautsky’s temporal and electioneering interpretation led him instead to criticize the pseudo-serendipity effects, not controlled by the SPD, that surrounded this type of political action.