The dispute over the construction of a social system theory, which took place in Harvard between P.A. Sorokin (1889–1968) and T. Parsons (1902–1979), is still drawing the attention of historians and theorists of sociology. Both scientists were greatly respected by the scientific community of those times, both had their unique vision on creating a social theory and, of course, each of them claimed priority in the development of their respective system-sociological theory. According to P.A. Sorokin, who in 1951 was promoting his work “Similarities and Dissimilarities Between Two Sociological Systems” among colleagues from his department and beyond it, T. Parsons’ essays on the topic of social system theory are suspiciously similar to P.A. Sorokin’s lectures and essays — an opinion which in turn was refuted by Parsons. In response to Sorokin’s claims, T. Parsons claimed that his theoretical concept had been influenced more by other authors than by P.A. Sorokin. He also pointed to the process of convergence in system theory and highlighted plenty of other differences between their system theories. All researchers noticed the severity of this conflict, but when we look to the circumstances of the end of this conceptual debate, we find that it is not entirely clear whether it was even resolved, and more importantly — how the conflict actually ended. Analysis of this historical case conducted through the lens of Luhmann’s communicative theory helps get a clearer understanding of the problem. It allows for separating the conceptual implications of the dispute from its other aspects – personal, career, psychological, institutional aspects — which ultimately allowed looking into the conceptual essence of the conflict. The use of new and previously little-known German archival documents, copies of sociologists’ personal letters, journal reviews on sociological theory, journal publications about the conflict allowed to establish the importance of the role played by respected German sociologist L. von Wiese (1876–1969), a personal friend of P.A. Sorokin and an expert in theoretical sociology, in deescalating the conflict and ending the dispute in 1952.