Nature has not willed man to be self-sufficient. Dependence is his very psychology. What is true of man is also true of States, for it is the people who make the State and the State exists for the people.
If mutual intercourse between States is not recognised and established, society is bound to stagnate. Modern economic, scientific, social and cultural developments have further cemented the ties of mutual interests and common affinity.
In fact, in the civilised world of today citizens of one country very largely share in the thought, the art, and the literature of the neighbouring communities.
Mutual contact between States is strengthened if citizens of countries politically separate, for instance, India and Pakistan, speak a common language or “where a kindred descent enables them to look back to the same history and traditions in the past.”
The relations between States demand their regulation in the same way as many subjects himself to certain rules of conduct in his dealings with his fellow-citizens.
In the beginning, the rules of conduct between States were rudimentary and not uniform in character. Now there is an increasing tendency to conform them to a definite code of conduct.
Uniformity and definiteness are necessitated by the greater economic and social interdependence of peoples or nations. Without such rules there would be confusion and chaos and all causes of disputes would have to be settled by the arbitrament of war.