Liberty Matters

Ius Gentium, the Law of Nations, and the Law of Nature at the Birth of Liberalism

Fernando Tesón rightly insists on a distinction that is part and parcel of modern international law: that between positivism and natural jurisprudence. I say rightly, because it is on these dimensions that modern international law developed. The question is: what has it to do with Grotius? And another: what with liberalism?
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The old distinction in Roman law was between ius civile and ius gentium, respectively, the law that applies to citizens of Rome and that which applies to all people indistinctively. For the practice of Roman imperialism, this was a useful distinction, no doubt, but it had nothing to do with international law: the normative cadre of Roman imperialism had its origins in the legal concepts of Roman ius civile. Thus part of the problem is the equivocal expression ius gentium, meaning both that law that is shared by all peoples and (yet only from somewhere around the 17th and 18th centuries) the law that holds between nations. For example, when in 1672 Samuel Pufendorf titled his magnum opus De iure naturae et gentium (On the Law of Nature and Nations) he made it a point of principle to identify the two, criticizing Grotius for failing to do so. About international law Pufendorf had preciously little to say, i.e., because he strongly believed that nations were in a state of nature relative to each other, and thus considered the law of nature sufficient as a normative context. Whatever Grotius and Pufendorf were discussing, it was not the status of international law, but the law of nature.
Now if we agree with Hayek (Law, Legislation, and Liberty: A New Statement of the Liberal Principles of Justice and Political Economy, vol. 2 The Mirage of Social Justice [University of Chicago Press, 1976], p. 59.) that the term natural law “ought to be avoided,” then we might want to know what other term to use: human rights? (global) justice? (international) law? The choice is somewhat arbitrary since each of these has good claims to being the heir of natural law. I will opt for the human-rights/global-justice pair, also because historians of international law are canvassing the effects in their field (e.g., Martti Koskiennemi). That Grotius is relevant to human rights seems obvious, and to the second concept as well, if we accept the following definition:
Global public reason is a standpoint “from which positions are to be justified by way of giving reasons people of different moral or political backgrounds could accept.” [Mathias Risse, On Global Justice (Princeton: Princeton University Press, 2012), p. 94.]
And this is in the spirit of Grotius, who understood natural law indeed to be a set of normative principles that are valid independent of religious or political preferences. Hayek for good reasons questions the very idea of immutable principles – both the immutability and the principledness, evidently – and I would suggest that it makes best sense of Grotius to see him lean in that direction too.
This issue of global public reason is best developed by drawing attention to a topic very central to Grotius, viz., consensus, that we might translate as agreement, shared judgment, or consent, depending on the precise context. The term is first introduced in his major conjuring trick, by which he removed God from the equation. Natural law, he says, are the moral principles pertinent to man, and naturally these depend on God the Creator of the world. In order to know these principles, however, Grotius does not point towards our religious understanding of God, but to our own understanding of our own nature, as created by God. Our moral principles are those that belong to our nature, and we have to study our own nature in order to find out. German theologians in the 17th and 18th centuries called this derogatorily “naturalism,” as if it was a way of handing over moral responsibility to naked nature. But that was not the case: in order to find out the nature of man and its moral implications, we need to study, and as Alexander Pope said so famously: ‘The proper study of mankind is man.”  And the hallmark of good results is that they can command agreement among the researchers: consensus. As we all know, such a consensus sometimes is a travesty, because based on “political correctness,” on brutal power even, or ideological bias, sometimes on ignorance of true causes. So in the end, “consensus” is a process concept; it has to be amended and corrected; consensus thrives by dissension and debate. Grotius, e.g., points at consensus when showing that his core notion of self-defense is recognized by all philosophical currents, including the Skeptics. (Part of his eclecticism has to do with the importance of consensus in natural-law argument.)
Why do we want to know the moral principles belonging to man? Grotius’s answer was that moral principles that mankind can universally agree on allow us to end and/or prevent wars, since wars are only justified in case of a lesion of these principles. This argument is circular, evidently, but the circle is sufficiently large to make it worthwhile.
It is different with other agreements. People(s) can agree on many things: on religious obligations, on political obligations, on manifest destinies or tax regimes, on international alliances or trade agreements. All these agreements have the force of law implied in their respective agreements, and it is a separate intellectual and/or political game to sort out the precise implications of such arrangements.
The effort to find out what moral principles are inherent in man’s nature is thus based on consensus, on reasons acceptable to all concerned. And here is the great difference with consent. When I consent to something, I am considered obligated because of the act of consenting. But when I agree to a reason, it is not the act of agreeing that has moral force on me, but the content of the reason.
If I agree to become a slave (because I have good grounds to fear that I otherwise might be killed), then I engage in a legal form that is dictated by the polity I live in. In the times of Hobbes (who elaborated on this example from Grotius), slavery was accepted in many parts of the world. (See the discussion between John Cairns and Gustaaf van Nifterik in Grotiana vol. 22/23, 2001-2002, pp. 197-244.) Although one may doubt whether slavery conforms to the moral principles inherent in mankind, there was at that time no consensus that it did not. Besides, in the Grotian example the voluntary slaves are those taken prisoner in a just war and who have forfeited their property and life by unjust warfare. It is the Nuremberg Tribunal version of natural law, not the war of all against all of Hobbes. But no doubt later, “more advanced” ages have seen new consensus on reasons grow, and the direction of these new developments are in interesting ways in line with Grotian ideas.
In John Rawls’s The Law of Peoples (Cambridge, Mass.: Harvard University Press, 1999), we find an important attempt to develop a consensus based universal set of moral principles. Mathias Risse’s On Global Justice is a more recent elaboration of a similar set-up. Interestingly, Risse takes recourse to Grotius throughout the book, claiming that especially in the concept of the earth as the common property of mankind, and in the way in which Grotius developed private property out of it, we find ingredients for global public reason. And thus it is all about liberalism as well, especially as it turns out that the basic ingredients that go into the equation are property and trade.