One cold Chicago day last February, I watched a Federal Express delivery man carry an armful of boxes to his truck. In the middle of the icy street, he slipped, scattering the boxes and exposing himself to traffic. Without thinking, I ran into the street, stopped cars, hoisted the man up and helped him recover his load. Pondering this afterward, I realized that my tiny act of altruism had been completely instinctive; there was no time for calculation.

We see the instinctive nature of moral acts and judgments in many ways: in the automatic repugnance we feel when someone such as Bernie Madoff bilks the gullible and trusting, in our disapproval of the person who steals food from the office refrigerator, in our admiration for someone who risks his life to save a drowning child. And although some morality comes from reason and persuasion — we must learn, for example, to share our toys — much of it seems intuitive and inborn.

Many Americans, including Francis Collins, director of the National Institutes of Health and an evangelical Christian, see instinctive morality as both a gift from God and strong evidence for His existence.

As a biologist, I see belief in God-given morality as American's biggest impediment to accepting the fact of evolution. "Evolution," many argue, "could never have given us feelings of kindness, altruism and morality. For if we were merely evolved beasts, we would act like beasts. Surely our good behavior, and the moral sentiments that promote it, reflect impulses that God instilled in our soul."

So while morality supposedly comes from God, immorality is laid at the door of Charles Darwin, who has been blamed for everything from Nazism to the shootings in Columbine.

Why it couldn't be God

But though both moral and immoral behaviors can be promoted by religions, morality itself — either in individual behavior or social codes — simply cannot come from the will or commands of a God. This has been recognized by philosophers since the time of Plato.

Religious people can appreciate this by considering Plato's question: Do actions become moral simply because they're dictated by God, or are they dictated by God because they are moral? It doesn't take much thought to see that the right answer is the second one. Why? Because if God commanded us to do something obviously immoral, such as kill our children or steal, it wouldn't automatically become OK. Of course, you can argue that God would never sanction something like that because he's a completely moral being, but then you're still using some idea of morality that is independent of God. Either way, it's clear that even for the faithful, God cannot be the source of morality but at best a transmitter of some human-generated morality.

This isn't just philosophical rumination, because God — at least the God of Christians and Jews — repeatedly sanctioned or ordered immoral acts in the Old Testament. These include slavery (Leviticus 25:44-46), genocide (Deuteronomy 7:1-2; 20:16-18), the slaying of adulterers and homosexuals, and the stoning of non-virgin brides (Leviticus 20:10, 20:13, Deuteronomy 22:20-21).

Was God being moral when, after some children made fun of the prophet Elisha's bald head, he made bears rip 42 of them to pieces (2 Kings 2:23-24)? Even in the New Testament, Jesus preaches principles of questionable morality, barring heaven to the wealthy (Matthew 19:24), approving the beating of slaves (Luke 12:47-48), and damning sinners to the torments of hell (Mark 9:47-48). Similar sentiments appear in the Quran.

Now, few of us see genocide or stoning as moral, so Christians and Jews pass over those parts of the Bible with judicious silence. But that's just the point. There is something else — some other source of morality — that supersedes biblical commands. When religious people pick and choose their morality from Scripture, they clearly do so based on extrareligious notions of what's moral.

Further, the idea that morality is divinely inspired doesn't jibe with the fact that religiously based ethics have changed profoundly over time. Slavery was once defended by churches on scriptural grounds; now it's seen as grossly immoral. Mormons barred blacks from the priesthood, also on religious grounds, until church leaders had a convenient "revelation" to the contrary in 1978. Catholics once had a list of books considered immoral to read; they did away with that in 1966. Did these adjustments occur because God changed His mind? No, they came from secular improvements in morality that forced religion to clean up its act.

 

Where, then?

So where does morality come from, if not from God? Two places: evolution and secular reasoning. Despite the notion that beasts behave bestially, scientists studying our primate relatives, such as chimpanzees, see evolutionary rudiments of morality: behaviors that look for all the world like altruism, sympathy, moral disapproval, sharing — even notions of fairness. This is exactly what we'd expect if human morality, like many other behaviors, is built partly on the genes of our ancestors.

And the conditions under which humans evolved are precisely those that would favor the evolution of moral codes: small social groups of big-brained animals. When individuals in a group can get to know, recognize and remember each other, this gives an advantage to genes that make you behave nicely towards others in the group, reward those who cooperate and punish those who cheat. That's how natural selection can build morality. Secular reason adds another layer atop these evolved behaviors, helping us extend our moral sentiments far beyond our small group of friends and relatives — even to animals.

Should we be afraid that a morality based on our genes and our brains is somehow inferior to one handed down from above? Not at all. In fact, it's far better, because secular morality has a flexibility and responsiveness to social change that no God-given morality could ever have. Secular morality is what pushes religion to improve its own dogma on issues such as slavery and the treatment of women. Secular morality is what prevents ethically irrelevant matters — what we eat, read or wear, when we work, or whom we have sex with — from being grouped with matters of genuine moral concern, like rape and child abuse. And really, isn't it better to be moral because you've worked out for yourself — in conjunction with your group — the right thing to do, rather than because you want to propitiate a god or avoid punishment in the hereafter?

Nor should we worry that a society based on secular morality will degenerate into lawlessness. That experiment has already been done — in countries such as Sweden and Denmark that are largely filled with non-believers and atheists. I can vouch from experience that secular European nations are full of well-behaved and well-meaning citizens, not criminals and sociopaths running amok. In fact, you can make a good case that those countries, with their liberal social views and extensive aid for the sick, old and disadvantaged, are even more moral than America.

Clearly, you can be good without God.

Jerry A. Coyne is a professor in the Department of Ecology and Evolution at The University of Chicago. His latest book is Why Evolution is True, and his website is www.whyevolutionistrue.com.