The concepts of “public conscience” and “principles of humanity” have played a crucial role in the evolution of international law in the last century. The ambiguity of the terms, and the lack of a clear definition and scope, have permitted a creative application of the principles and have fostered extensive interpretations of norms. This post intends to examine these non-legal concepts, in an attempt to further strengthen their contribution to the development of international law.
The role of public conscience and dictates of humanity in the evolution of international law
The international law principles of “laws of humanity” and “dictates of public conscience” have gained relevance during the 19th Century. First mentioned in the so-called Martens Clause, these principles were reiterated, albeit with varied wording, in several humanitarian law and human rights treaties. Their role and purport in international law were examined by the International Court of Justice and by human rights bodies. International Criminal Tribunals, from Nuremberg to the ICTY, also relied on these principles. They are currently recognized as principles of international law, applicable in times both of armed conflict and of peace.
The existence of a public conscience that expresses “sentiments of humanity” is a phenomenon conceived at the end of the 18th Century and has been growing ever since. The affirmation of this notion in international law allowed progressive interpretations of international agreements by judges and treaty bodies, and a constant evolution of customary law.
The notion of public conscience, meaning public opinion, or vox populi, played a crucial role in promoting negotiations of treaties and conventions. In so doing, it shaped a “large body of public international law derived from humanitarian sentiments and centred upon the protection of the individual”.
After the Second World War, indeed, the diffusion of democratic regimes in various continents, with the parallel phenomena of decolonisation, globalisation, and the – albeit partial – democratisation of the international system, provided the public opinion with a fundamental role in the evolution of international law. Media development, together with technologies, gave further strength to the phenomenon. Across the decades, plenty of observers monitored and reported the positions of States delegations in diplomatic meetings. In so doing, the presence of civil society mitigated the adoption of decisions based purely on State interests, and promoted decisions taken in the interests of other sectors of society, or again, for the common interests of mankind.
As for the notion of humanity, it has also played a crucial role in the conclusion of international agreements in the last century. The history of the law of treaties experienced a gradual change. From bilateral treaties concluded in the name of state interests, and mainly under the principle of reciprocity, multilateral treaties thrived, throughout the 20th Century and especially from the aftermaths of World War II, with a different purpose: to safeguard the common interests of mankind.
Public opinion is considered to have crucially contributed, for instance, to the adoption of treaty prohibitions on bacteriological (biological) and chemical weapons; to the negotiation of the 1997 Ottawa treaty, a disarmament treaty prohibiting antipersonnel land mines; and to the inclusion, in the Rome Statute of the International Criminal Court, of the war crime of conscripting and enlisting children into armed forces or groups. 
This view of the impact of public opinion on the adoption of treaties implies a univocally positive influence of public opinion on the evolution of international law: in so doing, it gives an oversimplified perspective of the “public conscience” notion , which takes for granted that the vox populi only advocates positive instances of protection of human dignity and peaceful relations in the international community. Rather, the public conscience has a wide range of opinions and sentiments to be expressed, e.g. discriminations and hatred based on identity. So far, its voice was generally expressed by NGOs advocating progressive instances of humanitarian concern and of human rights protection. Should the trend of public involvement persist, different opinions and sentiments, not necessarily corresponding to the interests of humanity, could enter the international debate. The complexity of the concepts at stake invites a deeper reflection, in order to fully enquire into the potential value of these principles.
Sentiments of humanity, a possible definition
In order to find a definition for “sentiments of humanity” it is worth using the theory offered by a recent branch of psychology, which stems from an interpretation that is spread widely over various cultures since ancient history. This theory distinguishes between three kinds of human “sentiments”, which reflect istinctivity, emotivity and rationality. The three originate from different parts of the brain, respectively: the cerebellum, the limbic system and the neocortex, typical of different phases of the evolution of the human species. The three can be defined with the greek words of the three kinds of love: eros, philia and agape.
Eros is the instinctual feeling. It is related to anger, to joy, to sexual passion, but it is also related to inner values, e.g. a sense of justice. The deep feeling that allows distinction between what is right and what is wrong. In this interpretation, the concept of eros encompasses its etymological opposite, thanatos, by including both positive and negative instincts. Agape is the emotive side of love, reflecting the Latin word caritas. It relates to affection and a sense of protection towards the family. It is the love between mother and son, brother and sister, and also the kind of faith that links religious entities to human beings. Finally, philia is the admirative and contemplative love. It allows understanding and cognisance of being part of the entire humanity, to feel empathy for other human beings, not only for family or national links, but in the quality of members of mankind.
Each kind of sentiment has a certain impact on positions and opinions that concern the international community. For example in a situation of armed conflict, Eros is logically associated to violence, to the brutal instinct that leads people to harm other people. At the same time, it can inspire action against war and its consequences. For instance, it might be the instinctual feeling that inspired the first development of the laws of armed conflict, with Henry Dunant’s action after the battle of Solferino. The most powerful leaders are similarly inspired by strong inner values of righteousness and justice.
In the same way, agape’s impact is twofold. As an emotive love, it can foster solidarity among people; it can rebuild confidence and trust in communities. But agape can also have a negative impact as far as it constitutes an exclusive, and not an inclusive, sentiment. The feeling of agape is not directed towards any other human being, it is not erga omnes. Rather, it is directed to a specific group of people, of the same family, the same identity. Consequently, agape contributes to building divisions between people and nations. Furthermore, since agape encompasses love towards a divinity, it can foster religious hatred or fanaticism.
Philia is the only kind of love to inspire empathy towards all human beings, without personal gain, without distinction of nationality, religion or any other identity ground. It can be defined as the consciousness of being interlinked to all other human beings. It allows one to feel and conceive that mankind has common interests to pursue. Philia is the specific “love towards humanity” that contributed to the evolution of international law. Fundamental concepts of international law such as “crimes against humanity”, the ICRC’s fundamental principle of humanity and the concept of “public conscience” mentioned in the Martens Clause, are permeated by this “humanitarian sentiment”, as it is the inalienable and universal human dignity, which is the basis of human rights law.
In the last century, public conscience has played a crucial role in the evolution of international law, and it can still contribute to the development of humanitarian protection and human dignity in general. However, it is necessary not to overlook the possibility of negative manifestations of public conscience and to promote only one specific aspect, i.e., the consciouness of being part of the same humanity, or philia. This is the notion that so far has emerged in international negotiations, constituting the background condition allowing international actors to advocate international law agreements and, ultimately, pursue the common interests of mankind.
 First included in the Hague Convention II with Respect to the Laws and Customs of War on Land of 1899.
 Theodor Meron, The Humanization of International Law, Brill Nijhoff, The Hague, p. 21, 2006.
 Meron, op. cit., p. 23.
 International Court of Justice, Corfu Channel Case, Individual Opinion by Judge Alvarez, 1949.
 Tetsuya Toyoda, Influence of Public Opinion on International Law in the Nineteenth Century, Alberta Law Review, Vol 46, No 4, 2010.
 Jean Pictet, The need to restore the Laws and Customs relating to armed Conflicts, in International Review of the Red Cross, 9, pp 459-483, 1969.
 “In fields such as public health, communications, maritime security, protection of maritime resources, literary, artistic and scientific property, metrological unification, and protection of certain basic human rights, multilateral treaties were called upon to serve an entirely new purpose: the defence of the common interests of mankind.”
Paul Reuter, Introduction to the Law of Treaties 2-3 (2nd ed. 1995) cit. in Meron, op. cit.
 The three examples are proposed by Theodore Meron, op. cit. p. 21-23.
 Claudio Naranjo, Character and Neurosis: An Integrative View. (Gateways). Nevada City, 1994.