 The ‘Core Cognition’ hypothesis. Many developmentalists in this camp share a commitment to the ‘Core Cognition’ (sometimes called ‘Core Knowledge’) hypothesis (Carey 2009; Carey &amp; Spelke 1996; Spelke et al. 1992; Spelke 1998, 2000, 2003). According to this hypothesis, evolution has equipped our species (and other species too) with an innate repertoire of conceptual representation types, that is, representations that cannot be reduced to the perceptual primitives favored by the Empiricists or the sensory-motor primitives favored by Piagetians. Rather, evolution has shaped our perceptual input analyzers to detect certain types of entities in the world, and has provided us with principles—embodied in our cognitive machinery—that determine how we (at least initially) think about such entities. These different types of entities are few in number. To date, there is a consensus among proponents of this hypothesis that the innately specified core domains include physical objects, number, and minds.[19] Proponents of the Core Cognition view defend a moderate Nativism; they leave work for learning mechanisms, which, together with maturation, take the infant from limited ‘core’ conceptual systems to the broad and highly elaborated knowledge of the world that adults have. In some cases, adult knowledge extends the core; in others it ‘over-writes’ it. The conceptual machinery that embodies a core domain is often referred to as an ‘intuitive theory’—for instance, a folk physics or folk psychology (sometimes theory of mind)—to highlight the fact that each supports patterns of conceptualization of input and inference.  There is intense ongoing work on core domains, and research paradigms are being extended to non-human animals and across cultures.  In the sections that follow, we review select findings on three domains: physical objects, number, and intentional agents.[20] We concentrate on very early development. While it is often difficult to say what exactly the research reveals about the young child’s knowledge (for methodological as well as philosophical reasons), the earlier some distinctive elements of a competence are present, the less likely that it was learned solely on the basis of experience.