Editing Jurisprudence (section)

====H.&nbsp;L.&nbsp;A. Hart====
{{Main|H. L. A. Hart}}

In the English-speaking world, the most influential legal positivist of the twentieth century was [[H.&nbsp;L.&nbsp;A. Hart]], professor of jurisprudence at [[Oxford University]]. Hart argued that the law should be understood as a system of social rules. In ''[[The Concept of Law]]'', Hart rejected Kelsen's views that sanctions were essential to law and that a normative social phenomenon, like law, cannot be grounded in non-normative social facts.

Hart claimed that law is the union of primary rules and secondary rules.{{sfn|Hart|2012|pp=79–99}} Primary rules require individuals to act or not act in certain ways and create duties for the governed to obey.
Secondary rules are rules that confer authority to create new primary rules or modify existing ones.{{sfn|Hart|2012|p=81}} Secondary rules are divided into rules of adjudication (how to resolve legal disputes), rules of change (how laws are amended), and the rule of recognition (how laws are identified as valid). The validity of a legal system comes from the "rule of recognition", which is a customary practice of officials (especially barristers and judges) who identify certain acts and decisions as sources of law. In 1981, Neil MacCormick<ref>{{Cite web|url=http://www.law.ed.ac.uk/staff/neilmaccormick_51.aspx|title=The University of Edinburgh|archive-url=https://web.archive.org/web/20060601221401/http://www.law.ed.ac.uk/staff/neilmaccormick_51.aspx|archive-date=1 June 2006|url-status=dead|access-date=24 May 2006}}</ref> wrote a pivotal book on Hart (second edition published in 2008), which further refined and offered some important criticisms that led MacCormick to develop his own theory (the best example of which is his ''Institutions of Law'', 2007). Other important critiques include those of [[Ronald Dworkin]], John Finnis, and [[Joseph Raz]].

In recent years, debates on the nature of law have become increasingly fine-grained. One important debate is within legal positivism. One school is sometimes called "exclusive legal positivism" and is associated with the view that the legal validity of a norm can never depend on its moral correctness. A second school is labeled "inclusive legal positivism", a major proponent of which is Wil Waluchow, and is associated with the view that moral considerations {{em|may}}, but do not necessarily, determine the legal validity of a norm.