 A second challenge to massive modularity is posed by the ‘Domain Integration Problem’ (Carruthers, 2006). The problem here is that reasoning, planning, decision making, and other types of high-level cognition routinely involve the production of conceptually structured representations whose content crosses domains. This means that there must be some mechanism for integrating representations from multiple domains. But such a mechanism would be domain general rather than domain specific, and hence, non-modular. Like the Input Problem, however, the Domain Integration Problem is not insurmountable. One possible solution is that the language system has the capacity to play the role of content integrator in virtue of its capacity to transform conceptual representations that have been linguistically encoded (Hermer &amp; Spelke, 1996; Carruthers, 2002, 2006). On this view, language is the vehicle of domain-general thought. 