Ideations of ‘natural law’ have existed in European culture since the Greeks and Romans. Aristotle and Cicero wrote about it, and it was recognized in Christian theology by Thomas Aquinas.
The renaissance idea of natural law encapsulates the common thread that “man is by nature a rational and social animal” who willingly cooperates with others for their mutual benefit, and the recognition that to do so requires some limitations on individual conduct. Certain values are necessary for any civilized society to exist.
Stealing, for example, undermines the trust necessary for any society to survive. Murder defeats the original purpose (individual safety) of being part of a community. So all civilized societies have an “agreement… upon matters considered the law of nature”. These are seen as immutable laws necessary for a civilization to exist, that can not be altered by government.
The prosecution of the Nazi leadership for “crimes against humanity” was based on natural law. The Holocaust was entirely legal under the “Nuremberg Laws” enacted by the German government controlled by the Nazi Party. Stalin’s Gulags, and the Cambodian “killing fields”, were legal under laws enacted by the governments that perpetrated those atrocities. But they were contrary to natural law.
Our American idea of natural law existed in pre-Columbian north America. The Haudenosaunee (Iroquois confederation) of the Hudson Valley region structured their tribal society on the belief that each individual was free of all but minimal control by the community.
Adriaen Van der Donck, the resident lawyer for the Dutch West India Company that founded a colony in New England, described the Haudenosaunee as “[A]ll free by nature, and will not bear any domineering or lording over them.” Thomas Jefferson was aware of the Iroquois Confederation when he wrote about our “inalienable” right to “life, liberty, and pursuit of happiness” in the Declaration of Independence.
Under natural law, we each have the right to life, and to defend ourselves accordingly. Killing in self-defense has been recognized as “excusable homicide” in all civilized societies.
“Liberty” means the freedom to acquire and dispose of the fruits of our labors as we think best (“pursuit of happiness”). The reason humans originally formed communities was to secure mutual protection for themselves (life), their crops, herds, and trade goods (private property). Government evolved to provide both security from external threats, and a formal mechanism to resolve internal conflicts between community members about property. Some of the earliest recorded legal cases involve disputes over ownership of domesticated animals or farm land.
Those early cases became what we know today as the “common law”, which is law made by judges based on natural law. Their rulings became binding (stare decisis) on resolution of future similar disputes, thus providing the stability necessary for members of the community to conduct their affairs. Trade can succeed only if everyone knows, and plays, by the same rules.
The American idea of natural rights is that government exists only to provide security and stability for life and property. In his discourse on Civil Disobedience, natural law adherent Henry David Thoreau wrote, “Government that governs the least, governs best!” Founding philosopher Thomas Paine called government “a necessary evil”.
Jefferson explained “governments are created among men”, with their consent, to secure their natural rights. This is the “social contract” whereby members of a group give up some individual freedom in exchange for collective security and stability.
Under the “contract” government’s authority is limited to those narrow functions. When a government exceeds its limited role under the “contract” those who created it have the natural right to void the contract and change the government. That’s what we did in 1776, and we retain the natural right to do so again. The Second Amendment secures our ability to exercise that right.
That is the essence of limited government based on natural law from Aristotle down through the Iroquois Confederation and our own revolution against England. Natural law, and the rights derived from it, are not a grant from government. They supersede government, which has no legitimate authority to infringe them. Our whole concept of government is based on that idea.
The antithesis of natural law is socialism, which assumes humans must be compelled to cooperate as a community by the government controlling everything. Like the National Socialists (Nazis) did, and advocates of our current cancel culture do. They differ only in degree. At least for now.