Abstract
The article describes the most inconsistent and contradictory modal categories of obligation and necessity presented in linguistics. Many scientific papers have been devoted to the study of modality in general and its particular varieties. Interest in its research is caused by the increased attention to the role of language as a means of communication and individualization of the human thought and speech process. The relevance of the problem is also in line with the general trend of improving, ordering, and systematizing the conceptual and terminological apparatus of linguistics. Subjective modality has a multiple semantics, various means of expression, and a number of possible relationships between form and content in the process of speech functioning. These characteristics result in contradictory and confusing interpretations of these categories in science. The research objective was to determine the content basis of these modalities and show how they are interdependent. The study was based on the methods of analysis, comparison, and generalization. The article focuses on the relationship between obligation and necessity in the general field of modality, as well as on their linguistic nature. The types of unreal modality proved to be different varieties of modality with a common area of semantics and use. The author generalized an extensive theoretical material on the categories of obligation and necessity, identified their meanings, and provided a basis for further research. The results of the analysis can also be used in courses of theoretical and applied philology.

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