The goal of the paper is to describe Jakub Karpiński’s sociology and specifically – his theory of Communism. It extends the Girardian concept of „novelistic conversion” to show that sociologists, just as novelists, undergo conversion that makes them realize that they are dependent on something they can give witness to. Already in the beginning of his academic career, Karpiński decided to serve his scholar and national community. His further work articulated what he fought against and what he fought for. In consequence, he constructed an integral theory of Communism, which validates, describes the bygone system as well as points to ways of overcoming it: truth and solidarity.