Abstract
The nature of vagueness is investigated via a preliminary definition and a discussion of the classical sorites paradox ; this is carried further by asking for the origins of vagueness and a critique of several attempts to remove it from language. It is shown that such attempts are ill motivated and doomed for failure since vagueness is not just a matter of ignorance but firmly grounded in epistemic and metaphysical facts. Finally, the philosophical interest of real vagueness is illustrated by the concept of “natural kind”, which is essential to realism/anti-realism debates.