   The above view can be paraphrased, somewhat crudely, as the claim that any truth seemingly about a class can be reduced to a claim about some or all of its members. For example, it follows from this contextual definition of class terms that the statement to the effect that one class A is a subset of another class B is equivalent to the claim that whatever satisfies the defining propositional function of A also satisfies the defining propositional function of B. Russell also sometimes described this as the view that classes are “logical constructions”, not part of the “real world”, but only the world of logic. Another way Russell expressed himself is by saying that a class is a “logical fiction”.  While it may seem that a class term is representative of an entity, according to Russell, class terms are meaningful in a different way.  Classes are not among the basic stuff of the world; yet it is possible to make use of class terms in significant speech, as if there were such things as classes. A class is thus portrayed by Russell as a mere façon de parler, or convenient way of speaking about all or some of the entities satisfying some propositional function.