Offers psychologist Baldwin's theory as an approach to the development of social understanding emphasizing gradual differentiation of self and other and rooting this process in embodied activity within a social context. Argues that Baldwin's account provides a stronger starting point for conceptualizing the infant's discovery of other, self, and mind than the analogical assumption. Suggests amendments to the Baldwin theory grounding self-other differentiation in collaborative interactions between self and other. (Author/KB)