This paper argues that there is a difference between the concept of law and the validity of law. Whereas the concept of law provides the criteria of what law is, its validity signifies that law belongs to a certain system of meaning (e.g., a social, moral, or legal order). Accordingly, a norm that can properly be called law may or may not have legal, social, or moral validity (first thesis: separation of concept and validity of law). The first function of validity is to distinguish a particular system of meaning from others (second thesis: separation of different forms of validity). The validity of legal norms may depend on other systems of meaning such as morals (justice, equality, etc.) or social behavior (effectiveness, enforcement, acceptance, etc.) or not (third thesis: moral or social validity is not a necessary condition for the validity of law). Only norms that are law and are legally valid are also legally binding (fourth thesis: validity of law is a necessary condition for its bindingness).