ABSTRACT
Species monists claim that all species are members of one, fairly homogeneous kind of entities (the species category) that can be characterised by one metaphysical account of what species are. Species pluralists disagree and hold that the term ‘species’ covers a diversity of entities, such that there is no unified metaphysical account of the nature of species – there are different accounts for the different kinds of entities, but no account that covers them all. While at present, species pluralism is the dominant position, it leaves one important question unanswered: if the term ‘species’ refers to a variety of kinds of entities, what makes them all into species, and why do we treat them as somehow comparable kinds of entities? This chapter answers that question by exploring a middle way between species monism and species pluralism. This involves distinguishing between the theoretical meaning of ‘species’ and the practical usages of the term. I argue that while ‘species’ is a homonymic term in biological practice, it still is possible to identify a theoretical idea that unifies the different usages to a certain extent. This idea, I suggest, is that the term ‘species’ does not denote a kind of entities but rather, a status that can be attributed to a group of organisms on theoretical grounds. Following the view of species developed by Dobzhansky in the 1930s–1940s, I suggest that the theoretical basis for such a status attribution is the question of whether a group represents a stage in the evolutionary process.
