It is proposed that NP's determined by the generic indefinite article represent abstract concepts, and as such are not inherently different from indefinite NP's appearing in copulative predicates. A derivation for generic indefinite NP's that reflects this is formulated (and evidence is adduced to show that any cannot underlie generic a ); this is shown to be explanatory as regards the phenomenon itself, its relationship to other kinds of generic NP's, and its relationship to other kinds of indefinite NP's. It also enables us to formalize the notion of ‘generic sentence’.