 Hart, by contrast, did not understand his project as centrally focused on the grounds of law. Hart [1961] offered various, non-equivalent characterizations of his central task. In the first chapter, he suggests as a central aim the differentiation of law from a variety of other phenomena, specifically morality, religion, and coercion. In the preface, however, Hart suggests that his study might be regarded as an essay in “descriptive sociology.” The answer to the former question would rely on what Dworkin [2006] called a taxonomic concept of law that distinguished law from other social phenomena; the latter question, by contrast, demands what Dworkin [2006] called a sociological concept of law that furthers the aims of social science.