Species pluralists respond to this objection by suggesting criteria for judging the legitimacy of a proposed species concept (Dupré 1993, Ereshefsky 2001). Such criteria can be used to determine which species concepts should be accepted into the plurality of legitimate species concepts. Candidate criteria are the epistemic virtues that scientists typically use for determining the scientific worthiness of a theory. For example, in judging a species concept, one might ask if the theoretical assump