Day 1 of 28
The Law of Human Nature
Everyone Knows the Rules
Scripture Readings
Today's Reading
Read Romans 2:14-15: "For when Gentiles, who do not have the law, by nature do what the law requires, they are a law to themselves, even though they do not have the law. They show that the work of the law is written on their hearts, while their conscience also bears witness."
Then read Psalm 19:1: "The heavens declare the glory of God, and the sky above proclaims his handiwork."
Reflection
Lewis opens Mere Christianity not with theology but with an observation anyone can verify: people quarrel. Not just fight — quarrel. They appeal to standards. They say "that's not fair" and "you promised" and "how would you like it?" These are not mere expressions of preference. They are appeals to a rule that both parties recognize, even when one of them is breaking it.
"Every one has heard people quarrelling... They say things like this: 'How'd you like it if anyone did the same to you?' — 'That's my seat, I was there first' — 'Come on, you promised.' People say things like that every day."
Lewis's point is deceptively simple: the very act of arguing about right and wrong presupposes that right and wrong exist. If morality were merely personal taste — like preferring chocolate to vanilla — there would be nothing to argue about. But we do argue, passionately, because we believe there is a real standard being violated.
"Quarrelling means trying to show that the other man is in the wrong. And there would be no sense in trying to do that unless you and he had some sort of agreement as to what Right and Wrong are."
This is where Lewis begins his case. Not with the Bible, not with church authority, but with the common human experience of moral awareness. He is asking: what does this universal sense of "ought" tell us about the kind of universe we live in?
Paul makes a strikingly similar argument in Romans 2. Even those who have never heard of Moses or the Ten Commandments demonstrate knowledge of a moral law "written on their hearts." Conscience is not culturally constructed from scratch — it is a response to something real, something planted in us.
Going Deeper
Lewis's starting point matters because it meets people exactly where they are. You do not need to accept the authority of Scripture to recognize that you have a conscience, that you believe in fairness, and that you consistently fail to live up to your own standards. These are the raw materials from which the entire argument of Mere Christianity will be built.
Today, pay attention to how often you (or those around you) appeal to an unwritten standard. Notice how naturally the words "that's not right" come to your lips. Then ask: where does that conviction come from?
Key Quotes
“Every one has heard people quarrelling... They say things like this: 'How'd you like it if anyone did the same to you?' — 'That's my seat, I was there first' — 'Come on, you promised.' People say things like that every day.”
“Quarrelling means trying to show that the other man is in the wrong. And there would be no sense in trying to do that unless you and he had some sort of agreement as to what Right and Wrong are.”
Prayer Focus
Asking God to awaken your awareness of the moral law He has written on every human heart
Meditation
When was the last time you appealed to a standard of fairness in a disagreement? Where did that standard come from?
Question for Discussion
If moral standards are just social conventions, why do we get genuinely angry — not merely annoyed — when someone breaks a promise or cuts in line? Does your group think this universal sense of 'ought' points to something beyond human invention, or can it be fully explained without God?