The fundamental concept of classical liberalism is the idea of negative freedom: freedom as the absence of coercion. But what is coercion? Why is coercion considered an evil from a liberal perspective? Friedrich A. von Hayek develops a definition of the pair of concepts freedom and coercion, which remains incomplete and raises some fundamental questions about his moral philosophy and theory of cultural evolution. Philipp Batthyány undertakes an immanent definition of Hayek's concept of coercion and provides a justification for the reprehensibility of coercion as a fundamental evil in society. By incorporating essential parts of the unpublished estate, he analyzes Hayek's entire work with regard to the underlying conception of freedom and coercion, thereby filling an important gap in Hayek research.