Hart's Minimum Content of Natural Law

Although a positivist, Hart accepted that some truth lay in natural law. In The Concept of Law he described a 'minimum content of natural law': rules that any legal system must contain if it is to serve the basic aim of human survival. He grounded these not in divine reason but in simple facts about humans. People are vulnerable to bodily harm, so laws must restrict violence. They are approximately equal, so no one can dominate everyone for long without cooperation. Their altruism is limited, so rules are needed to curb selfishness.

Resources are limited, so some form of property is necessary. And people have limited understanding and strength of will, so sanctions are needed to back rules for those tempted to break them. Hart's argument shows that the line between natural law and positivism is less sharp than it seems: even a positivist can admit that human nature shapes what any workable legal system must include, while still denying that injustice cancels legal validity.