 The phylogenetic diversity measure illustrates how the pattern—process framework differs from the objects and differences approach. For PD, the objects are species (or other taxa) and the units that we would like to count-up are features (or characters). The use of phylogeny (the “tree of life”) to make inferences about the relative feature diversity of different sets of species is a way to overcome our lack of knowledge about all the features of different species. Maclaurin and Sterelny (2008: 20) incorrectly interpreted PD as an application of the objects and differences approach, with species as objects and differences given by “genealogical depth”. Instead, a pattern (phylogeny) among the species is used. This pattern allows inferences about the biodiversity units of interest—here, features or characters of species.