 Because classes would at first seem to be individuals of some sort, but on analysis are found not to be, Russell speaks of them as “logical fictions,” an expression which echoes Jeremy Bentham’s notion of “legal fictions.” (Hart 1994, 84) (See entry on  law and language).  That a corporation is a “person” at law was for Bentham merely a fiction that could be cashed out in terms of the notion of legal standing and of limits to the financial liability of real persons. Thus any language about such “legal fictions” could be translated in other terms to be about real individuals and their legal relationships. Because statements attributing a property to particular classes are replaced by existential sentences saying that there is some propositional function having that property, this construction also can be characterized as showing that class expressions, such as ‘\(\{x:Fx \}\)’, are incomplete symbols. They are not replaced by some longer formula expressing a term. On the other hand, the definition should not be seen as avoiding ontological commitment entirely, as showing that something is literally a “fiction”. Rather it shows how to reduce classes to propositional functions. The properties of classes are really properties of propositional functions and for every class said to have a property there really is some propositional function having that property.