 A survey of the sorts of values biologists used in the second half of the 20th Century for accepting or rejecting species concepts shows that biologists typically used epistemic values. Many biologists wanted species concepts that helped biologists make inferences about the members of particular species (for example, Mayr 1982 and Eldridge and Cracraft 1980). That is, species concepts should pick out those species taxa such that if we know that an organism belongs to a particular species, we can infer that this organism probably has a particular property. To put it another way, species concepts should identify species that allow us to make projective inferences. Other epistemic values that biologists want species concepts to have include simplicity, generality, and uniformity (see Ereshefsky 2001 for further discussion).