Article. Questions of Philosophy . — 1974. — No. 2 . — C. 116-126. The mathematicalization of a particular field of knowledge has become almost equivalent to the penetration into this field of concepts and methods of set theory. But when a field of science occupies such an important position, it becomes absolutely necessary to clarify both the questions of the logical validity of the theory itself, and the questions of the adequacy of this theory to those real objects and processes that it is designed to describe and explain. Accordingly, the article deals with the problems associated with the relationship of the concept of set to various categories that more directly describe reality.