 Thus, with pronouns in discourse anaphora, we have examples of pronouns that can neither be understood as picking up their referents from their antecedents nor as being variables bound by their antecedents. Discourse anaphora provides further interesting examples to philosophers and linguists when the antecedents are under the scope of quantifiers, modals, or negation. For example, the pronouns in (19), (20), and (22) are infelicitous, but those in (21) and (23) are felicitous. This is something further that an account of discourse anaphora needs to  explain.[8]