 Arp (2006) defends a hypothesis about a kind of module—scenario visualization—a psychological adaptation that arose in our hominid history in response to the demands of tool making, such as constructing spear throwing devices for hunting. Arp presents his hypothesis in the context of demonstrating the superiority of his approach to evolutionary psychology, which he calls “Narrow Evolutionary Psychology,” over “Broad Evolutionary Psychology,” with respect to accounting for archaeological evidence and facts about our psychology. While Arp’s hypothesis is innovative and interesting, he by no means defends it conclusively. This is partly because his strategy is to compare his hypothesis with archaeologist Steven Mithen’s (see e.g. 1996) non-modular “cognitive fluidity” hypothesis that is proposed to account for the same data. The problem here is that Mithen’s view is only one of the many alternative, evolutionary explanations of human tool making behavior. While Arp’s modular thesis may be superior to Mithen’s, he has not compared it to Sterelny’s (2003; 2012) account of tool making and tool use or to Boyd and Richerson’s (see e.g. 2005) account and hence not ruled these accounts out as plausible alternatives. As neither of these alternative accounts rely on the postulation of psychological modules, evolutionary psychology is not adequately defended.