Purpose. The purpose of the article is to analyze and systematize the views of social and political thinkers of Galicia in the 19th - beginning of the 20th centuries. on the right and manner of organizing a nation-state as a cathedral. Method. The methodology includes a set of general scientific, special legal, special historical and philosophical methods of scientific knowledge, as well as the principles of objectivity, historicism, systematic and comprehensive. The problem-chronological approach made it possible to identify the main stages of the evolution of the content of the idea of catholicity in Galicia's legal thought of the 19th century. Results. It is established that the idea of catholicity, which was borrowed from church terminology, during the nineteenth century. acquired clear legal and philosophical features that turned it into an effective principle of achieving state unity and integrity. For the Ukrainian statesmen of the 19th century. the idea of catholicity became fundamental in view of the separation of Ukrainians between the Russian and Austro-Hungarian empires. The idea of unity of Ukrainians of Galicia and the Dnieper region, formulated for the first time by the members of the Russian Trinity, underwent a long evolution and received theoretical reflection in the work of Bachynsky's «Ukraine irredenta». It is established that catholicity should be understood as a legal principle, according to which decisions are made in dialogue, by consensus, and thus able to satisfy the absolute majority of citizens of the state. For Galician Ukrainians, the principle of unity in the nineteenth century. implemented through the prism of «state» and «international» approaches. Scientific novelty. The main stages of formation and development of the idea of catholicity in the views of social and political figures of Halychyna of the XIX – beginning of the XX centuries are highlighted in the work. and highlighting the distinctive features of «national statehood» that they promoted and understood as possible in the process of unification of Ukrainian lands into one state. Practical significance. The results of the study can be used in further historical and legal studies, preparation of special courses.