In a recently published book, Roger Shiner shows that understanding the fundamental discrepancies between different legal theories is important for a better understanding of law itself. He argues that one of the most important tasks of legal philosophers is to take into account the dynamics or conceptual movements generated by positivism and antipositivism. Our paper intends to show that Shiner's analysis can be developed and modified when other relevant elements are introduced into the universe of discourse. We emphasize the importance of a positivistic conception of legal science. According to Shiner, an adequate theory of law must reproduce the way in which legal norms work in the lives of the participants who accept the law. After analyzing the distinction between norms and norm propositions and the relationship between legal science and the external point of view, we show that legal positivism is not committed to reproducing the internal point of view to law.