Fodor has argued against developmental psychology. He contends that most concepts are innate, that little of importance can be learned, and that stage development cannot occur. Fodor considers mental representations to be static encodings. He is correct in arguing that new kinds of encodings cannot be learned. Novel encodings are unlearnable, however, because encodings are not a coherent foundation for knowledge in the first place. The alternative is a conception of representation as interactive. From an interactive standpoint, representation can be explicated coherently, and learning and stage development can be explicated without paradox. To the extent that developmental frameworks equate knowledge with encodings, they will be vulnerable to Fodor’s arguments. The alternative is to build consistently interactive models of knowledge and development.