We argue for an example of “core cognition” based on Diamond and Carey's (1986) work on expertise and recognition, which is not made use of in The Origin of Concepts. This mechanism for perceptual learning seems to have all the necessary characteristics in that it is innate, domain-specific (requires stimulus sets possessing a certain structure), and demonstrably affects categorisation in a way that strongly suggests it will influence concept formation as well.

Carey leaves unaddressed an important evolutionary puzzle: In the absence of a numeral list, how could a concept of natural number ever have arisen in the first place? Here we suggest that the initial development of natural number must have bootstrapped on a material culture scaffold of some sort, and illustrate how this might have occurred using strings of beads.

Carey proposes a theory of conceptual development that specifies innate conceptual representations that get learning started. Those representations are the output of innate domain-specific input analyzers. I contend that innate core cognition about agency is itself a gradual construction and that the role of Quinian bootstrapping needs elaboration to account for the development of intuitive theories of psychology.

The Origin of Concepts sets out an impressive defense of the view that children construct entirely new systems of concepts. We offer here two questions about this theory. First, why doesn't the bootstrapping process provide a pattern for translating between the old and new systems, contradicting their claimed incommensurability? Second, can the bootstrapping process properly distinguish meaning change from belief change?

Carey's superb discussion of the origin of concepts is extended into the field of cognitive ethology. I also suggest that agency may be a default mechanism, often leading to over-attribution. The problem therefore becomes one of specifying the conditions in which agency is not attributed. The significance of attentional/focusing abilities on conceptual development is also emphasized.

Are infants' initial object representations innately specified? We examine the development of perceptual completion in infants by highlighting two issues. First, perceptual completion is supported by neural mechanisms that rely on experience with the environment. Second, we present behavioral and modeling data that demonstrate how perceptual completion can emerge as a consequence of changes in visual attention and oculomotor skill.

Carey's book describes many cases in which children develop new concepts with expressive power that could not be constructed out of their input. How does she side-step Fodor's paradox of radical concept nativism? I suggest that it is by rejecting the tacit assumption that psychology can only explain concept acquisition when it occurs by rational inference or other transitions that are explicable-by-content.

According to Carey (2009), humans construct new concepts by abstracting structural relations among sets of partly unspecified symbols, and then analogically mapping those symbol structures onto the target domain. Using the development of integer concepts as an example, I give reasons to doubt this account and to consider other ways in which language and symbol learning foster conceptual development.

Carey focuses her attention on a mechanism of concept learning called “Quinian bootstrapping.” I argue that this form of bootstrapping is not dependent upon language or other public representations, and outline a place for language in concept learning generally. Language, perception, and causal reasoning are all sources of evidence that can guide learners toward discovering new and potentially useful categories.

I make two points in this commentary on Carey (2009). First, it may be too soon to conclude that core cognition is innate. Recent advances in computational cognitive science and developmental psychology suggest possible mechanisms for developing inductive biases. Second, there is another possible answer to Fodor's challenge – if concepts are merely mental tokens, then cognitive scientists should spend their time on developing a theory of belief fixation instead.

The commentators raised issues relevant to all three important theses of The Origin of Concepts (henceforth TOOC). Some questioned the very existence of innate representational primitives, and others questioned my claims about their richness and whether they should be thought of as concepts. Some questioned the existence of conceptual discontinuity in the course of knowledge acquisition and others argued that discontinuity is much more common than was portrayed in TOOC. Some raised issues with my characterization of Quinian bootstrapping, and others questioned the dual factor theory of concepts motivated by my picture of conceptual development.