Whereas states are borne out of societies through the association of men with the aim of their common protection and self-preservation, international law is borne out of the association between various states and their preservation vis-à-vis one another. Originally borne out of the necessity to govern the practice of diplomacy and war, international law now largely addresses the customs and conventions which govern commerce between states. To a large extent, contemporary international law is borne out of international commerce. Conventions such as the “Law of the Seas” and so forth are borne out of the necessity to govern the conduct of international commerce between states in a growingly interconnected world.
On the other hand, the conventional law that addresses issues such as commerce, diplomacy, and war is borne out of natural law, according to experts in the field of international law. In essence, there is natural law on one hand, and conventional law on the other hand. Thus, for conventional law to be legitimate, conventional law must conform to natural law. In turn, natural law is derived largely from either philosophy or religious canon and scriptures. In sum, natural law – and thus conventional law – is intended to keep everything in its natural state, whereas war is an aberration and is a departure from a natural state. As Hugo Grotius wrote: “So that preserving ourselves in a natural state, and holding to every thing conformable, and averting everything repugnant to nature is the first duty.”
Thus, the primary aim of war is “the preservation of our lives and persons,” according to Grotius. In turn, there is lawful war, distinct from unlawful or unjust war aimed at hegemony, and it is aimed at self-preservation and “the possession or acquirement of things necessary and useful to life” and in turn conforms to natural principles such as self-defense and self-preservation. As a result, our understanding of what constitutes the “propriety” of war stems from our knowledge of natural principles. As Grotius wrote:
“But from the knowledge of these principles, a notion arises of their being agreeable to reason, that part of a man, which is superior to the body. Now that agreement with reason, which is the basis of propriety, should have more weight than the impulse of appetite; because the principles of nature recommend right reason, as a rule that ought to be of higher value than bare instinct.”
“As the truth of this is easily assented to by all men of sound judgment without any other demonstration, it follows that in inquiring into the laws of nature the first object of consideration is, what is agreeable to those principles of nature, and then we come to the rules, which, though arising only out of the former, are of higher dignity, and not only to be embraced, when offered, but pursued by all means in our power.”
And after deriving international law from natural principles or natural law, what preserves international law, according to Grotius, is nothing other than the “good faith” of individuals and states. As Grotius wrote: “For good faith…is not only the principal hold by which all governments are bound together, but is the key-stone by which the larger society of nations is united.” Without good faith between individuals and nations, even the complexities and necessities of commerce which bring nations together can be overridden, for as René Guénon argued, commerce alone breeds bare interests, and the brute pursuit of bare interests can lead to conflict and war, as evinced in recent years.