By Peter Kreeft, The Catholic Thing, Nov. 19, 2019
We don’t need religious faith or supernatural divine revelation to know that we’re morally obligated to choose good and avoid evil or to know what “good” and “evil” mean. Every culture in history has had some version of the Ten Commandments. No culture in history has thought that love, kindness, justice, honesty, courage, wisdom, or self-control was evil — or that hate, cruelty, injustice, dishonesty, cowardice, folly, or uncontrolled addiction was good. Speaking of pagans, St. Paul says that “they show that what the law requires is written on their hearts, while their conscience also bears witness” (Rom 2:15).
The term “natural law” is sometimes misunderstood. “This law is called ‘natural,’ not in reference to the nature of irrational beings [that is, animals — it is not a law of biology], “but because reason, which decrees it, properly belongs to human nature” (CCC #1955). For example, the Church teaches that artificial contraception is against the natural law, not because it’s a rational human intervention rather than an irrational biological process, but because it’s contrary to right reason. It violates the integrity of human nature by divorcing the two naturally united aspects of the essence of the sexual act — the unitive and the procreative — that is, personal intimacy and reproduction.