Question: Which English jurist largely developed legal positivism?

Context articles: Lon L. Fuller
Law's Empire
Legal positivism
Hozumi Yatsuka
Heinrich Triepel
Jeremy Bentham
The Concept of Law
Legal realism
Legal Positivism (book)
Matthew Kramer

Lon Luvois Fuller (June 15, 1902 – April 8, 1978) was a noted legal philosopher, who criticized legal positivism and defended a secular and procedural form of natural law theory.
 Fuller was professor of Law at Harvard University for many years, and is noted in American law for his contributions to both jurisprudence and the law of contracts.
 His debate in 1958 with the prominent British legal philosopher H. L. A. Hart in the "Harvard Law Review" (Vol.
 71) was important in framing the modern conflict between legal positivism and natural law theory.
 In his widely discussed 1964 book, "The Morality of Law", Fuller argues that all systems of law contain an "internal morality" that imposes on individuals a presumptive obligation of obedience.
 According to law professor Robert S. Summers, "Fuller was one of the four most important American legal theorists of the last hundred years."
Law's Empire is a 1986 text in legal philosophy by the late Oxford scholar Ronald Dworkin which continues his criticism of the philosophy of legal positivism as promoted by H.L.A. Hart during the middle to late 20th century.
 The book notably introduces Dworkin's Judge Hercules as an idealized version of a jurist with extraordinary legal skills who is able to challenge various predominating schools of legal interpretation and legal hermeneutics prominent throughout the 20th century.
 Judge Hercules is eventually challenged by Judge Hermes, another idealized version of a jurist who is affected by an affinity to respecting historical legal meaning arguments which do not affect Judge Hercules in the same manner.
 Judge Hermes' theory of legal interpretation is found by Dworkin in the end to be inferior to the approach of Judge Hercules.
Legal positivism is a school of thought of analytical jurisprudence, largely developed by eighteenth- and nineteenth-century legal thinkers such as Jeremy Bentham and John Austin.
 While Bentham and Austin developed legal positivist theory, empiricism and logical positivism set the theoretical foundations for such developments to occur.
 The most prominent legal positivist writing in English has been H. L. A. Hart, who in 1958 found common usages of "positivism" as applied to law to include the contentions that:
Hozumi Yatsuka (穂積 八束 , March 20, 1860 – October 5, 1912) He entered University of Tokyo at the age of nineteen after studying English for six years because many professors were foreigners who lectured in their own language.
 In 1883 after his graduation he entered the graduate school to continue his studies of political science.
 In August 1884 he went to Germany to study European institutional history and constitutional law.
 During his stay in Germany he studied at three universities: Heidelberg, Berlin and Strasbourg.
 In Strasbourg he studied under Paul Laband whose influence on Hozumi was profound.
 Laband was the foremost German representative of the school of legal positivism.
 In this usage positivism means an exclusive preoccupation with positive law, the law actually promulgated by a competent lawgiver.
 The central concept of Laband's theory was that of the legal personality of the state.
 He grounded sovereignty in this legal personality above and apart from its constituent members.
Heinrich Triepel (12 February 1868, Leipzig – 23 November 1946) was a German jurist and legal philosopher.
 From 1913, he was professor of law in Berlin.
 He took critical aim at legal positivism, which at the time was the dominant legal conception in the German-speaking world.
Jeremy Bentham ( ; 15 February 1748 [O.S. 4 February 1747] – 6 June 1832) was an English philosopher, jurist, and social reformer regarded as the founder of modern utilitarianism.
The Concept of Law (ISBN  ) is the most famous work of the legal philosopher H. L. A. Hart.
 It was first published in 1961 and develops Hart's theory of legal positivism (the view that laws are rules made by human beings and that there is no inherent or necessary connection between law and morality) within the framework of analytic philosophy.
 In this work, Hart sets out to write an essay of descriptive sociology and analytical jurisprudence.
 "The Concept of Law" provides an explanation to a number of traditional jurisprudential questions such as "what is law?"
, "must laws be rules?"
, and "what is the relation between law and morality?"
.
 Hart answers these by placing law into a social context while at the same time leaving the capability for rigorous analysis of legal terms, which in effect "awakened English jurisprudence from its comfortable slumbers".
 As a result Hart's book has remained "one of the most influential text of analytical legal philosophy", as well as "the most successful work of analytical jurisprudence ever to appear in the common law world"
Legal realism is a naturalistic approach to law.
 Legal realists believe that the legal science should investigate law exclusively with the value-free methods of natural sciences, also called 'sciences of the real' in some Continental languages (e.g., 'Realwissenschaften', in German).
 Some legal realists (e.g., Leon Petrażycki and Max Weber) also hold that there should exist, too, a legal dogmatics, which is independent of legal science proper but, this notwithstanding, can be regarded as a science in its own right (and so, despite its being a non-real, or formal, science).
 However the focus of all legal realists is on legal science proper.
 Due to their value-free approach, legal realists are opposed to natural law traditions.
 Legal realists regard these traditions as historical and/or social phenomena to be explained by making use of a variety of psychological and sociological hypotheses.
 They are also opposed to any form of linguistic turn in jurisprudence.
 When applied to law, they regard the linguistic turn as a sort of 'emasculation' (Enrico Pattaro) of legal phenomena.
 This is so because legal realists conceive legal phenomena as psychical phenomena, and, notably, as a form of "moral motivation" of human behavior (to be investigated with the methods of psychology and/or neurosciences).
 All this implies that legal realists are opposed to most versions of contemporary legal positivism.
 A further difference from all sorts of legal positivism is that legal realists refuse to confine their investigations to state law and/or positive law.
 Moreover, legal realists have a conception of law that stretches far beyond legal pluralism—so popular in many versions of classical and contemporary sociology of law.
 This is one of the reasons why legal realism cannot be regarded as a sort of sociology of law (other reasons being: legal realists' psychologism and their refusal of the linguistic turn—a turn that affected, too, sociology of law).
 Apart from Max Weber (who, owing to a variety of reasons, is mostly conceptualized as sociologist rather than as a legal realist), there are two strands of legal realism in this sense: Scandinavian legal realism, founded by Axel Hägerström (1868–1939), and Polish-Russian legal realism, founded by Leon Petrażycki (1867–1931).
 Both realisms, owing to their similarities (and despite their founders' ignoring one another), are sometimes referred to as 'continental legal realism' (in the singular).
Legal Positivism (Il Positivismo Giuridico) is a book by the Italian jurist Norberto Bobbio about one of the ontological elements of "foundations of law" — the "jusphilosophical school" called "juspositivism" or "legal positivism".
Matthew Kramer FBA (born 9 June 1959) is an American philosopher, currently Professor of Legal and Political Philosophy at the University of Cambridge and a Fellow of Churchill College, Cambridge.
 He writes mainly in the areas of metaethics, normative ethics, legal philosophy, and political philosophy.
 He is a leading proponent of legal positivism.
 He has been Director of the Cambridge Forum for Legal and Political Philosophy since 2000.
 He has been teaching at Cambridge University and at Churchill College since 1994.