The law of nature as a source of international law, reasone by correlation with the supposed primeval state of man, agrees that all independent political community is, by virtue of its independence, in a state of nature towards other communities; but they diverge in their conception as to what was the state of man in primeval nature.
Some assert that it was a contented being at peace with neighbors and observing the Golden Rule, while others maintain that from the dawn of history man has been affianced in a desperate struggle for existence not simply with nature but with his fellow men and is therefore naturally rapacious. The founder of what we may call the Pure Law of Nature School was Samuel Pufendorf (1632-1694), who occupied the first chair of the Law of Nature and Nations recognized in a university, namely, that at Heidelberg.
His most important work, De Jure Naturae et Gentium, was published in 1672. Pufendorf begins with the intention that in a state of nature, precursor to any act of man, all men must be considered as equal, that is, every man must enjoy a natural liberty in which he acts in his own right and is matter to the power of no other man (Pufendorf, 1934, p. 158); but man, he says, never did live at one and the same time in such a simple state of nature, for, according to Holy Writ, the family relationship began with the formation of man, and "therefore," to quote his words,
"a state of nature never really existed, except in some altered form, or only in part, as when, indeed, some men gathered collectively with others into a civil state, or some such body, but retained a natural liberty against the rest of mankind; though the more groups there were in this division of the human race, and the smaller their membership, the nearer it should have approached a pure state of nature. " "And so," he adds, "it was not the first men but their descendants who began indeed to live in a state of nature. " (p. 163. )
Natural law scholars usually believe that rules of international law are, at least in some way, part of an established order which inevitably predated the development of any contemporary legal system. Yet societies are forceful, even if the basic rules which structure their legal systems profess not to be. In the absence of an overarching sovereign the international legal system can be considered mainly dynamic legal system. At some point its members may consequently conceive — or conceivably they have already conceived in a different way of their requirements in terms of basic, peremptory rules.
The majority international lawyers would recognize that jus cogens rules themselves have not always existed. Consequently, it would seem that jus cogens rules cannot be rules of natural law, nor be based on such rules. Secondly, it is probable to understand general principles of law as being a kind of expected law based on the general principles, constitutional and statutory provisions, and court judgments of diverse national legal systems as forms of State practice (Guggenheim, Paul 1953).
Though jus cogens rules deny the right to form legal exceptions, there are several reasons why Lauterpacht's and the majority other people's understanding of general principles of law can be seen as at least partially subsumed by the larger process of customary international law, and why explanations which think about jus cogens rules to be derived from general principles of law must therefore be treated as locating those rules within the usual process (Cheng, Bin 1953).