 Let’s turn to the taxon question: Why are certain organisms members of species S? Relational essentialists argue that modern species concepts posit relational properties, such as interbreeding, genealogy, and occupying a specific niche, as the defining features of species. Relational essentialists tell us that biologists do not posit intrinsic properties as the defining features of species. Devitt responds (2008) that citing the relations among the organisms of a species does not explain why particular organisms are members of a certain species. According to Devitt, saying that organism O can interbreed with other Homo sapiens leaves unanswered why those other organisms are Homo sapiens. Then there’s an unanswered regress: why are any of them Homo sapiens? According to Devitt, to answer that question we must cite essential intrinsic properties in organisms.