Although Piaget’s psychological theory is developmental and ‘dialectical’ in a general way, lack of a developed philosophical basis leads to the subordination of a dialectical approach to static, anti-dialectical concepts. A study of Hegel’s theory of interaction and contradiction shows that the dialectical theory has a more precise meaning. Because Piaget regards mastery of formal-logical categories of identity, noncontradiction and object permanence as a basic framework for analysis of the child’s thought processes, dialectical features of the child’s thought are seen as ultimately yielding to static, metaphysical thought processes. Suggestions in Piaget’s later thought that even such categories are relative and transitory points to the need of developed, scientific dialectics, both as a further stage of intellectual development and as a framework for conceptualizing the dynamics of intellectual development at all stages.