 Brandon (2006), however, argues that “eliminating heterozygosity” is not sufficient to show that drift is directional, given that (as Stephens would readily acknowledge) if there were two alleles at a locus, beginning at equal frequencies, we could not predict which of the two alleles would go to fixation, only that one of them would; Brandon likens this to saying that “a 20-Newton force is acting on object A”, (2006: 325), which, he seems to imply, is not a directional claim. Moreover, he argues, drift is not a separate process from selection. Thus, drift, on Brandon’s view, is not a force (but it is a law; more on that below). Joshua Filler (2009) responds to Brandon by defending a more elaborated account of what a force is (in part drawing on Bigelow et al. 1988); on that elaborated account, drift’s direction can be seen as less specific than selection, mutation, and migration, but it gives some directional information. Thus, Filler argues, it can be seen as less “forcelike” than selection, mutation, and migration, but it is still a force. Charles Pence (2017), however, worries that Filler’s modifications to our understanding of “force” may be ad hoc, so he offers an alternative defense of the claim that drift is a force. First, Pence argues, we already countenance forces that have stochastically specified directions, such as Brownian motion, and drift is analogous. Second, we can create an evolutionary thought experiment where drift is absent, showing that it is not constitutive of all evolving systems; this is intended to respond to Brandon’s claim that drift is not separable. Importantly, however, Pence points out that there are essential questions that the entire debate has yet to address: “what exactly the use of ‘forces’ is to do for us, and when explanations utilizing a force metaphor are useful or perspicuous” (Pence 2017: 1975).