Common references to rights can be divided into legal rights and moral rights, depending on whether the claim in question is grounded on the authoritative sources (e.g., statutes, judicial decisions, or constitutional provisions) of a particular legal system, or on a moral theory. Jeremy Bentham famously argued that talk of moral rights (or natural rights or human rights) was simple nonsense, nonsense upon stilts. The idea is that while legal rights have a clear correlate in the world, in legal texts and the willingness of legal officials to enforce them through various enforcement procedures, no such clear correlate exists for moral rights. However, this skeptical view of moral rights is not shared by many