Joe Biden believes there is something in the philosophical tradition called an “evolving view of natural law:”
Natural law reasoning must be dynamic, capable of change. Only with expanding conceptions of “due process,” “equal protection,” and rights “reserved to the people” can the development of individual rights and liberties keep pace with the other changes in our country.
Biden deployed this mythical philosophical creature in 1991 when trying to block Justice Clarence Thomas from sitting on the Supreme Court. People interested in ethical theory know that natural law is opposed to relativism and historicism. Contrary to the idea that justice is reducible to national will and its history, natural law is the theory that right and wrong do not change because what it means to be human does not change. It is the claim that reason discerns the moral implications of our most basic desires, determining that certain things must be avoided and others pursued. These moral-bearing inclinations are few, and the obligations linked to them are also few. For this reason, and because our social lives are complex, a natural law theorist acknowledges that these rational obligations must be supplemented by adjudications from positive law. Positive law—human and divine—does change with history. Tastes, mores, and circumstances evolve; deliberative bodies and judiciaries of varied polities craft, revise, and dispense with myriad laws as sensibilities and national conditions change.
Natural law does not change, but human positive law does. (Even divine positive law can change. The Christian God, at least, posits laws which he then later changes—marriage laws, for instance). In natural law reasoning, therefore, there is considerable need for human law to supplement natural law. Thomas Aquinas argues, for instance, that natural law demands murder be punished, and punishment may include the death penalty. However, what punishment is exacted for murder is left to the polities of different lands to determine for themselves. Punishment is set by human law.
Is human law infinitely elastic? No: some positive law determinations might conflict with the unchanging core of rational human nature. If a positive law clashes with those few, socially foundational obligations stemming from this fixed core, that law is unjust. Natural law trumps human law when push comes to shove. Natural law is the measure of the rationality of human law.
