Author: Başak Etkin & Alex Green

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A. Positivism as Method and IdeologyEdit

I. An International Legal History of PositivismEdit

1. Early Natural Law Thinkers and the Positivist TurnEdit

2. Lassa Oppenheim on the 'Science' of International LawEdit

3. Hans Kelsen and the Pure Theory of (International) LawEdit

4. HLA Hart and International LawEdit

2. Legal Positivism within Legal PhilosophyEdit

1. The Separation ThesisEdit

2. Legal Validity and the Sources of LawEdit

3. 'Conceptual' and 'Normative' PositivismEdit

4. State Consent and Legal PositivismEdit

B. Critiques of PositivismEdit

Legal positivism, in the sense canvassed here, is the view that legal norms are determined or ‘fixed’ as part of any given legal order ultimately on the basis only of their pedigree in relation to a given sets of social facts. The inverse view, held by ‘non-positivists’, is that international legal norms are necessarily determined not only by social facts but also by facts about political morality.[2] Take, for example, a claim such as ‘the 1969 Vienna Convention on the Law of Treaties expresses true propositions of international law’. For the legal non-positivist, this statement will only be true to the extent that the law-determining function of the Vienna Convention is morally valuable in some way.[3] This reliance upon political morality, perhaps counter-intuitively, is also entailed by the beliefs of normative positivists, like Oppenheim or Weil, who aver that for moral reasons international legal norms must be identified with recourse to social facts alone. To continue with the same example, a normative positivist and a committed non-positivist might both accept that the Vienna Convention helps to determine norms of international law because treaties in general have a coordinating function, which is valuable vis-à-vis the stability and predictability of international relations. For both schools of thought, in other words, treaty texts help to fix the content of international legal norms because there are compelling reasons why those texts should have this effect.

What, then, distinguishes non-positivists from normative positivists? Non-positivists, whilst agreeing that facts about political morality partly determine the content of the law, disagree that moral reasoning should be excluded from the identification of international legal norms at a more concrete level.[4] Normative positivists, as noted above, argue that international law should be identified with recourse to social facts alone. According to their view, excluding moral considerations from legal reasoning is, amongst other things, conducive to international stability, insofar as it avoids the proliferation of inter-state disputes. For the non-positivist, however, the exclusion of moral considerations from legal reasoning is wrongheaded, either because they believe normative positivists to be mistaken about the allegedly destabilising effects of moral reasoning,[5] or because they believe identifying international legal norms to be impossible on the basis of social facts alone. In what follows, we examine a few reasons why one might reject legal positivism wholesale, as it were, and adopt a non-positivist approach instead.

I. Insufficient ConsensusEdit

As we have seen, central to the positivism of Hart, Raz, and others, is the notion that legal validity turns on the existence of one or more rules of recognition. This claim can also be put in the following terms. Within any given legal order, the norms of that order are ultimately determined exclusively in relation to the convergent behaviours and attitudes of law applying officials; the social facts that such officials treat as being sources of law become sources for that reason.[6] Within international law, as we have seen, the relevant legal officials include state representatives and international adjudicative bodies, to name but two examples. One possible reason for rejecting positivism of this kind, at least as far as international law is concerned, is the belief that insufficient convergent in official attitude or behaviour exists within that system, such that no rule of recognition can be said to exist there.[7] This, interestingly enough, is close to the view that Hart himself professed about international law,[8] even if it has become unpopular amongst positivist international lawyers.[9] Recent scholarship has renewed attacks against positivism within international law along these lines.[10] Importantly, such criticisms raise issues for not just for analytical positivism but also for normative varieties. This is so because if international law possesses no rules of recognition (or some set of norms fulfilling the same function and determined both ultimately and exclusively by social facts) then legal reasoning in a fully positivist mode is impossible, no matter how advantageous it might be in principle.

2. ‘Rational’ Determination and Social FactsEdit

Another doubt one may have about rules of recognition stands in relation to their law determining function as such. Even if there are sufficiently convergent attitudes and behaviours amongst international legal officials to constitute one or more rules of recognition, it is unclear why these attitudes and behaviours alone should be treated as having a law determining effect.[11] According to a broadly Hartian view of legal validity, the law determining function of official practices follows effectively by definition. However, on the plausible assumption that legal norms must be identified to exist for a good reason, it is not obvious why this definitional move should hold.[12] This concern arises because the attitudes and practices of legal officials themselves are social facts, with no necessary normative implications, and therefore cannot provide such reasons in and of themselves.[13] Importantly, this critique is inapplicable to normative positivism, which holds that facts about political morality can explain why ultimate and exclusive recourse to a particular set of social facts should be observed.[14] Nonetheless, concerns about the ‘rationality’ of positivism remain applicable to its purely analytical variants, notwithstanding this fact.

3. The ‘Positive’ Non-Positivist CaseEdit

Finally, one might wish to appeal directly to political morality within legal reasoning for more positive reasons. In the first place, on the assumption that either of the first two critiques presented above are true, then reliance upon more than just social facts alone is inevitable when identifying international law, at least at higher levels of abstraction. This being so, there is no point, or so the argument might go, in pretending otherwise. It is preferable to be transparent about one’s reliance upon political morality, instead of obscuring it behind a positivist veneer. Alternatively, one might believe that direct recourse to moral considerations within legal reasoning would be conducive to the promotion of global justice, if for no other reason than it focuses attention on the most morally salient aspects of a given international dispute.[15] Considerations of this sort have motivated a range of contemporary non-positivist scholarship, both in relation to international law in general,[16] and as regards more discrete regimes, such as the law of statehood,[17] international trade law,[18] or the law of human rights.[19]

Further ReadingsEdit

  • Source I
  • Source II


  • Summary I
  • Summary II

Table of ContentsEdit

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Part I - History, Theory, and Methods

Part II - General International Law

Part III - Specialized Fields


  1. The first footnote. Please adhere to OSCOLA when formating citations. Whenever possible, provide a link with the citation, ideally to an open-access source.
  2. Hasan Dindjer, ‘The New Legal Anti-Positivism’ (2020) 26(3) Legal Theory 181.
  3. Alex Green, ‘The Precarious Rationality of International Law: Critiquing the International Rule of Recognition’ (2022) 22(8) German Law Journal 1613, 1626.
  4. Ronald Dworkin, Law’s Empire (Hart 1986) 114-130, 238-258. The distinction as presented here may elide non-positivism and ‘soft’ positivism, which accepts that moral reasoning can indeed form part of legal reasoning but only to the extent that moral norms are ‘incorporated’ within the law by norms that are themselves determined ultimately and exclusively by social facts. For more on soft positivism, see: Eleni Mitrophanous, ‘Soft Positivism’ (1997) 17(4) Oxford Journal of Legal Studies 621.
  5. Nahuel Maisley, ‘Better to See International Law this Other Way: The Case Against International Normative Positivism’ (2021) 12(2) Jurisprudence 151.
  6. Green (n XXX) 1619-1620.
  7. Ibid 1627-1633.
  8. H.L.A. Hart, The Concept of Law (OUP 1994) 236.
  9. Jeremy Waldron, ‘International Law: “A Relatively Small and Unimportant” Part of Jurisprudence?’ in Luís Duarte d’Almeida, James Edwards, and Andrea Dolcetti (eds.), Reading H.L.A. Hart’S ‘The Concept of Law’ 209, 219–22 (Bloomsbury 2013); Mehrdad Payandeh, ‘The Concept of International Law in the Jurisprudence of H.L.A. Hart’ (2010) 21 European Journal of International Law 967, 989–93.
  10. Green (n XXX); David Lefkowitz, ‘What Makes a Social Order Primitive? In Defense of Hart’s Take on International Law’ (2017) 23(4) Legal Theory 258.
  11. Mark Greenberg, ‘Hartian Positivism and Normative Facts: How Facts Make Law II’ in Scott Hershovitz (ed.), Exploring Law’s Empire: The Jurisprudence of Ronald Dworkin (OUP 2006) 273.
  12. Mark Greenberg, ‘How Facts Make Law’ (2004) 10 Legal Theory 157, 164.
  13. Greenberg (n XXX).
  14. Green (n XXX) 1626-1627.
  15. John Tasioulas, ‘Customary International Law and the Quest for Global Justice’ in Amanda Perreau-Saussine and James Murphy, The Nature of Customary Law (CUP 2007) 326-329.
  16. Fernando Teson, A Philosophy of International Law (Perseus 1998); Ronald Dworkin, ‘A New Philosophy for International Law’ (2013) 41(1) Philosophy & Public Affairs 2.
  17. Alex Green, Statehood as Political Community: International Law and the Emergence of New States (forthcoming, CUP 2023).
  18. Oisin Suttle, Distributive Justice and World Trade Law: A Political Theory of International Trade Regulation (CUP 2018).
  19. George Letsas, A Theory of Interpretation of the European Convention on Human Rights (OUP 2007).