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Why The U.S. Founders Rooted The Legislative Branch In Natural Law

Our laws are intended to be an expression of our God-given ability to reason.


January 28 marks the Feast Day of St. Thomas Aquinas, a great theologian and poet. He is the patron saint of philosophers, scholars, students, and universities, and his works were heavily relied on by our American founders. Aquinas’ writings on the connection between God, reason, and natural law inspired the Constitution’s design of the law-making powers given to the legislative branch.

The founders were deliberate and cautious in how they distributed power among the three branches of government. When designing the separation of powers, the founders were hyper-aware that when power is centralized, it becomes tyrannical. So they intentionally developed each branch with its own unique purpose built to do a specific task, and ways to prevent the branches from accumulating one another’s power.

So what are the unique powers given to the legislative branch? The power to make laws. This is where Aquinas, as well as other political philosophers, comes in. The founders believed that the power to make laws was unique, compared to judicial and executive branches. It is, after all, a power ultimately given to us by God.

But how do humans have this natural reason, or understanding of what is a just or unjust law? In his Summa Theologiae, Aquinas theorized about natural law and how God “instructs us by means of His Law.” Thomas D. D’Andrea interprets:

Following Aristotle, Thomas teaches that through intellect the human soul is potentially all things: it ranges over the entire universe of what is, and by acts of understanding and inferring, it in a certain way brings the entire universe into the soul. Put another way, in conjunction with the will the intellect expands the soul to become all that is by a cognitive and affective, but not a physical, union.

Or, as Alexander Hamilton wrote, God gave us the rational faculties that allow us to understand law and to develop political systems that are consistent with it. What we really want out of our government are laws consistent with God’s laws and the laws of nature, with the end goal being that we can all enjoy our God-given rights (that life, liberty, and happiness mentioned elsewhere).

So how do we get from these natural laws to the stacks of legalese and penal codes we have today? The legislative body is the vital link between the general, natural laws and the specific laws that we all agree on as a society to enforce or restrict specific behaviors. No one person has the right to impose his interpretation or version of any one law on anyone else. But with a Congress, we can deliberate and reason our way to interpreting what is the best general and just law applicable to everyone. Our laws are intended to be an expression of our God-given ability to reason.

In Hillsdale College’s online course, “Congress: How It Worked And Why It Doesn’t,” which you can take here, Dr. Kevin Portteus explains how the power of lawmaking is rooted in reason, deliberation, and our God-given natural rights.