We argue that Russell’s treatment of propositions containing non-existent denotations is the prelude of a strategy for discerning the predictive content of any proposition with descriptions (and incomplete symbols), insofar as its indeterminacy is classifiable as a possible extension. We argue, further, that Russell’s theory of propositional functions is dedicated to explaining the discernibility of hypothetical propositions, through representing (what we call) the superextension of assertoric modal propositions. The indeterminacy of the truth of hypothetical propositions is thus paired with a second- order classification condition, expressing its conjectural content as the projected scope of instantiation of a propositional function; which in turn is the superextension of a modal predicate. Russell’s theory is his non-pragmatic answer to the problem of assertability in unstable and uncertain conditions. It involves a sophisticated thesis about the discernibility of complex contents, such as those represented by analogical and approximate denotations (descriptions, fictions, etc.), which classify more than one possibility of instantiation in different modal and intensional contexts. We will conclude this article by testing the assumption that Russell’s theory favors a coherentist theory, seeing that as it admits assertability conditions that are super-mapped in a system, or that derive from different orders of referential layers.