The concept of powerful knowledge (PK) has central dichotomies and contradictions, which this article questions. The origins, meaning, purpose and reality of PK are considered. PK is based in social realism, and the article suggests how critical realism could inform more illuminating analyses of knowledge and power. The two versions of realism are compared for their different approaches to dichotomies and dialectic, and to types of knowledge as sacred or profane. The dichotomies assumed in PK theory, which will be reviewed, are: separating concepts from values; informal everyday experience versus formal academic education; separating disciplines versus interdisciplinarity; passive versus active learning and curriculum versus pedagogy; and policies versus theories of power and knowledge. The article concludes that these dichotomies are unrealistic and unhelpful. If teaching informed by PK theory is to benefit students and society, and if knowledge is to be associated with power, it will be helpful to overcome or revoke the dichotomies, which are better understood through dialectical analysis, as shown throughout the article.