 The idea that there is some sort of bipartite distinction to be made between abilities has been a prominent theme in contemporary work on ability. It has been endorsed and developed, in different contexts, by Glick (2012), Vihvelin (2013), and Whittle (2010). It is an open question whether the bipartite distinctions in ability introduced by these authors are the same as one another, or the same as the one introduced here. It could be that there are several bipartite distinctions to be made in this area, or that we simply have one distinction under several names.