The article is about the conflict of interpretation of the conception of capitalist rationality in the frame of Post-Sombart’s debates. Contemporary theorists in the accounting history propose different conflict interpretation of Sombart’s theory. These interpretations let to elaborate new approach to the problem of the development of capitalist rationality and capitalism as a whole. It is maintained that the moral rhetoric based on the principle of justification in connection with practices of accounting is the origin of capitalist rationality. The principle of justification of dealing based on calculation functions as the moral argument justified man’s inclusion in the capitalist relationship. Capitalism is thinking not only as economical system but also as a discourse based on the rhetorical practices. These practices are the moral arguments legitimized business and entrepreneurial relations in everyday life.