But the study of law is neither science nor metaphysics; since law is a normative phenomenon, there must always be a practical reason for studying law. As a normative construct, law attempts to correct human behaviors according to some norm. It is the attempt to determine this normative facet of law that troubles both law-makers and philosophers of law. As we see in modern philosophies of law, there are two primary ways of understanding the normativity of law, which are based either on a natural law tradition (represented primarily by L.L. Fuller), and legal positivism, which attempts to break laws down into social facts, as opposed to facts of nature.
The natural law tradition as it applies to the philosophy of law is represented primarily by the 20th century philosopher L.L. Fuller, who developed eight ways to fail for any legal system in his work The Morality of Law (1967) . On Fuller’s word, if any of the eight normative principles are not represented within a government, a system will not be “legal”. Fuller argues for these principles to the extent that they represent the “internal morality of law” and that one is guided by such principles to create just laws, and straying from them makes one liable to creating evil laws (Fuller, 1967, p. 39). To that extent, Fuller seems to be following St. Augustine, a natural law philosopher, who said famously, “Unjust law is not law” (Marmor, 2001). On Fuller’s view, proper laws cannot be made without some reference to morality, making it a natural law thesis.
Legal positivism stands opposed to the natural law tradition, rejecting any natural basis for laws in “natural facts” for morality. H.L.A. Hart, who belongs to the legal positivist tradition, adheres to the (2) conventionality thesis, thinks conditions for legal validity exist within standards of recognition that produce best practices in making or modifying law. These stand because they are