Natural law assumes that there is a body of law setting a complete and immutable standard of judgment and that knowledge of this body of law can be obtained by the rational contemplation of by consulting a divine revelation.
A recent theory of natural law, by Rudolf Stammler, has sacrificed immutability and declared that natural law might have a changing content. Other doctrines have set side by side with a natural law, grounded in reason and a permanent sense of justice, another law arrived at by “convention,” that is, by a formal set of rules of conduct based on convenience or utility.
This latter body, known as “positive” law, is for enforcing officials, as much entitled to be called law as that which is derived from reason and the nature of man, although the latter is of greater moral authority.
The conception of law a body of formal rules that can be drawn up and learned, like the axioms or “common notions” of Euclidean geometry, is of course quite incorrect. But it is a fact that in civilized countries, especially in those that derive their civilization from the Mediterranean area, there are a great many rules of conduct which, whenever the questioned is presented, the courts would declare to be legal rules and which are almost the same for nearly all the areas of that civilization.
These rules concern the graver crimes of violence and fraud, whether directed against person or property. In the Western group, there is also a general agreement among the laws of every country in the organization of the family.
For example, monogamy is the only valid form of marriage, and the duty of support of minor children, that is, children below eighteen or twenty-one years old, is imposed on the parents. In Asia, and Africa, polygamy is generally lawful, except that economic conditions usually, but not always, make the prevailing family from monogamous, despite the legality of polygamy.
In both areas, again, private properly is a legal institution except in the Soviet Union and in those countries which have come under its influence or direct control. But even in these so-called communist countries, private property in some goods is recognized and is protected by law.
Neither monogamy nor the institution or private property can be said to be inescapably derived from the nature of man. But the wide acceptance of both by so large a part of civilized mankind make it possible to speak of a general law which, with its rejection of acts of violence and fraud, can form the nucleus of comparable systems in nations which otherwise show a great diversity of customs.
While a “general law” of civilized man is a term that has only the content just described, it may be seen that large areas can be described terms of “countries of the civil law” and “countries of the common law.”
Between them, they include the majority of civilized nations.