The predicates prefixed with the definite article that refer to one and only one individual are definite descriptions, while those prefixed with the indefinite article, some, all and so on that can refer to more than one individuals are indefinite descriptions. Can the definite descriptions identify the essence of individuals and take the place of proper names?

Existence and essence is a theme of existentialism, but here I will examine the relation between them from the viewpoint of linguistic philosophy.