As a wedding present to ourselves, my wife and I bought the DVDs of the original Star Trek, and these past few months, we've been working our way through them. For myself, it was a test: I hadn't seen most of these episodes since my childhood, and I was curious to see if they held up. I'm pleased to say that, for the most part, they more than hold their own. There's plenty to criticize, but after all this time, it hasn't lost its charm.

Despite everything that makes me roll my eyes about Star Trek - the dated special effects, the hammy acting, the hackneyed plots, the ludicrous science - there's a powerful heart of optimism beating beneath the surface of the show. The idea that human beings have conquered our own divisions and become united as a species, that we're setting out to explore the universe purely for the sake of exploration, that we've become members of a galactic civilization of intelligent life - for all these reasons, the world of Trek could be fairly described as a utopian vision of humanist philosophy. And that's why it's no surprise that Star Trek's creator, Gene Roddenberry, was himself a humanist and a nonbeliever.

As Susan Sackett, Roddenberry's longtime personal assistant, put it to a humanist group in Massachusetts:

Ms. Sackett said that Star Trek, like humanism, promoted ethics, social justice and reason, and rejected religious dogma and the supernatural.... She said Mr. Roddenberry, who lectured in Worcester in the 1990s, strived in his Star Trek ventures to affirm the dignity of all people.

"Rationality was the key... There was no recourse to the supernatural," she said.

Ms. Sackett said Roddenberry was so resolute about religion that he refused suggestions to add a chaplain to the crew of the starship Enterprise.

And Roddenberry himself said:

"I have always been reasonably leery of religion because there are so many edicts in religion, 'thou shalt not,' or 'thou shalt.' I wanted my world of the future to be clear of that." (source)

Brannon Braga, one of the original writers and producers, expressed similar thoughts at a 2006 atheist conference in Iceland:

STAR TREK, as conceived by Gene Roddenberry, portrays the epic saga of humanity's exploration of space and, in turn, their own struggles as a species. Every episode and movie of STAR TREK is a morality tale in which human beings find solutions to conflict through enlightenment and reason. Through science. Through wit and intellect. Through a belief in our potential as animals that can supercede our baser instincts. In Gene Roddenberry's imagining of the future (in this case the 23rd century), Earth is a paradise where we have solved all of our problems with technology, ingenuity, and compassion. There is no more hunger, war, or disease. And most importantly to the context of our meeting here today, religion is completely gone. Not a single human being on Earth believes in any of the nonsense that has plagued our civilization for thousands of years. This was an important part of Roddenberry's mythology. He, himself, was a secular humanist and made it well-known to writers of STAR TREK and STAR TREK: THE NEXT GENERATION that religion and superstition and mystical thinking were not to be part of his universe. On Roddenberry's future Earth, everyone is an atheist. And that world is the better for it.

Star Trek's humanist ethic comes through clearly in several classic episodes, including "Who Mourns for Adonais?", in which the crew of the Enterprise is confronted by an alien being who claims to be the god Apollo and demands their worship; or the Next Generation episode "Who Watches the Watchers?", in which the crew's existence accidentally becomes known to a primitive society, and they must convince those people that they are not gods.

With all that said, I'd be remiss if I didn't mention that Star Trek has spawned its own devotees who follow and imitate the show with an almost religious fervor. But even this, I think, is testimony to the hunger for an optimistic, humanist vision of the future, one not based on the supernatural, and that's the kind of thing that all atheists should be doing our utmost to provide.

Other posts in this series:

• The Contributions of Freethinkers

The Problem: Human beings are stubborn creatures, set in our ways, resistant to changing our minds once we've made a decision. Religious groups publish creeds which they believe must be taken on faith and should be maintained against all contrary evidence - and they consider the ability to do that a virtue, rather than a character flaw. Even when dramatic disconfirmation comes, such as the apocalypse failing to occur on a predicted date, a common response is for believers to become even more committed.

Human dogmatism rears its head in politics as well as in religion. The stubborn persistence of conspiracy theories, even in the face of overwhelming evidence and common sense, is an example. Pseudoscientific beliefs such as the fear that vaccination causes autism persist even after failing the tests their own advocates set for them, and as with religion, outside criticism only tends to make the true believers cling to their beliefs all the more tightly. Although some people do change their minds about beliefs that are important to them, the striking thing about these conversions is how rare and noteworthy they are. The obstinate nature of dogmatism slows human progress, fostering division and sectarianism and causing people to hold to wrong ideas long after they've been more than adequately disproven.

The Solution: To illustrate how emotion dominates reason in human behavior, Jonathan Haidt's book The Happiness Hypothesis compares the mind to a person riding an elephant. The rider can usually steer, unless the elephant decides it wants to go somewhere else. In a similar way, the brain's emotional centers have deep projections into the rational parts of our brains, but not vice versa. A person who's feeling angry or frightened can easily be induced to make bad decisions, and it's almost impossible to persuade someone to give up a pleasurable habit that's bad for them, even when they know it's harmful. And the sense of belonging to a group, of being on the side of good or having access to secret truths of which the rest of the world is ignorant, is a feeling that has powerful emotional rewards.

Because the stubbornly emotional, nonrational parts of the mind can override the rational parts, human beings easily fall into the trap of dogmatism. But there's no reason the mind has to be designed this way. Why not shape our brains so that the rational centers instead override the emotional ones, or at least so that the two of them are equally powerful? That way, we'd be more likely to consider the evidence supporting a proposition and not just whether it feels good to believe it. The emotional centers would still operate just as before - we wouldn't be Vulcans, we'd still be human beings who feel happiness, love, anger and fear - but it would be far easier to overrule irrational emotion with objective reason when the situation calls for it.

The Real Explanation: The tendency toward dogmatism is a legacy of our having evolved in a complex and dangerous world. Humans and our direct ancestors lived on the edge of survival, at the mercy of the weather and climate and constantly threatened by natural disasters, by predators, and not least, by invasion and warfare with other humans. Under these circumstances, when a tribe found one way of life that enabled them to survive - fishing, or herding, or hunting and gathering - they'd have a strong incentive not to change it unless forced to by circumstance. It's much safer to go with what you know will work, rather than risk death by striking out into the wilderness and trying something brand-new. And evolution has imprinted that lesson on our brains, steering human behavior with brain areas that reward us with positive feedback when we find something that works, and warn us away from the unknown with negative emotions like fear.

Our ability to reason is a recent adaptation, compared to the older and more primitive emotional drives that shape our behavior. In evolutionary terms, it's like a new branch freshly grafted onto a large, ancient tree. It's little surprise that it hasn't gained the ability to override those older impulses - but an intelligent creator, foreseeing the greater benefits we stand to gain through reason, most certainly could have designed it that way.

Other posts in this series:

• Reengineering Human Nature

If you're an informed observer of media, you may have heard of the so-called Bechdel test, popularized by cartoonist Alison Bechdel, that's used to judge the female-friendliness of movies and other media. For a movie to pass this test, it has to have:

(1) two or more female characters;
(2) who talk to each other;
(3) about something other than a man.

Despite this being such a low hurdle - it doesn't establish that the movie is in any way feminist, merely that it treats women as something more than an appendage or love interest of the male characters - it's amazing how many movies fail it. And once you're aware of this test, it's easy to notice when a movie doesn't pass. This makes it a classic example of consciousness-raising: it highlights Hollywood's tendency to create movies where women exist only in relation to men and not as individuals in their own right.

This is such a useful way of highlighting bias, I think it's worth creating a similar test for religion, to help believers notice sexism in their churches they might not have noticed. My suggestion is as follows. For a religion to pass this test, it has to have:

(1) at least one woman in a position of authority;
(2) who plays a formal, recognized role in shaping doctrine or practice;
(3) that is binding on male members of that religion.

Let me further explain the meaning of these tests. The first asks whether a religion has any roles of authority - any official position within the church that carries power - that are open to women, or whether female members are restricted to being lay members with no power. The second asks whether that authoritative role confers any power to actually define what will be the canonical elements of that religion - to issue decrees, to define the correct interpretation of holy books, to vote on church reforms, to shape official practice - and the like, or whether the only duties of that position are to passively transmit preexisting ideas. If women do have such authoritative roles, the third test asks whether they can set doctrine that applies to men who are members of that religion, or whether their decisions apply only to other women.

If a religion categorically excludes women from all positions of authority, it fails. If it gives women positions of authority, but only so that they can teach and pass on doctrine created by men, it fails. If it permits women to create doctrine, but doctrine that's only applicable to other women, it fails.

For instance, Islam, as it's currently practiced throughout most of the world, fails at the first criterion; women aren't permitted to be imams or to issue fatwas, or to do much of anything other than obey the dictates of men. The same is true of Mormonism, which deliberately bars women from its priesthood, of the Southern Baptists, and of Orthodox Judaism.

Roman Catholicism fails at the second criterion; it permits women to be nuns, thus passing the first test (if only barely). But cardinals, bishops and ultimately the Pope, the only church officials who can define what's authoritative in matters of belief and practice for Catholics, can only be men.

The conservative Anglicans currently threatening to break away from the rest of their church, meanwhile, would arguably fail at the third test. They wanted to permit women to be bishops only on the condition that a separate order of male-only bishops be created to minister to their congregations. This would imply that no male Anglican could be subject to a female bishop if he didn't want to be.

As with the Bechdel test, the mere fact that a religion passes this test doesn't mean that it's a feminist or egalitarian religion. It could still be appallingly sexist. It could still have rules that treat women as inferior to men. And it could still be harmful in any number of other ways. But I would argue that this test is the bare minimum - the first necessary, but not sufficient, step for any religion to genuinely treat women as equals.

Evolution is a blind tinkerer, lacking the foresight of human engineers. Rarely, if ever, does it discard established designs and start over fresh, even when that would be more efficient. Instead, it builds on and around past adaptations, using the old as a foundation for the new. This is true throughout the biosphere, and it's especially true of one of the most complex structures ever evolved, the human brain. The physical architecture of the mind shows, through and through, the evolutionary hacks and kludges that went into creating it.

In his book The Dragons of Eden, Carl Sagan points out that the human brain has a threefold division. The most complex and most recently evolved structure is the neocortex, responsible for rational judgment, self-control, long-term planning, and all those other characteristics we think of as most uniquely human. Below it, somewhat older, is the limbic system: shared by all mammals, producing feelings of parental love and pair-bonding. And oldest and most primitive, shared by all vertebrates, is the brainstem, which controls the instinctive drives and behaviors known as the four "F"'s - fight, flight, feeding, and reproduction.

And if you're feeling allegorical, you might notice a correspondence with the world's religions. No organized religion in existence today posits a god of the neocortex. A few of the best offer a god of the mammalian brain, but even they rarely aspire to anything higher. But most - the belligerent, aggrieved, crudely literal fundamentalist faiths that command the allegiance of hundreds of millions - have gods of the reptile brain. These deities well up from the brainstem, the evolutionary remnant that sees the world as a dark palette of anger, fear, hunger and lust. Like the promptings of the brainstem, they're concerned, more than anything else, with the lowest and most primitive animal drives: what we eat, how and with whom we have sex, whether we observe rituals and taboos relating to purity and contamination. Also like the promptings of the brainstem, the religions they preside over tend to include generous amounts of aggression, submission, and xenophobia, and inflexible rules on when these are to be displayed and toward whom.

Of course, I'm not saying that religion originates solely in the brainstem. Were that the case, we'd see distinctly religious behavior throughout the animal kingdom, which we obviously don't. Religion requires other mental capabilities that are largely unique to humans and other intelligent mammals - social dominance hierarchies, pattern-seeking behavior, and an awareness of personal mortality. Still, it's striking how close is the correspondence between the concerns of fundamentalist religion and the instinctive drives mediated by the most evolutionarily primitive part of our brains.

But from the rational perspective - the highest, most uniquely human perspective - it's clear how ridiculous and morally outrageous this is. The fundamentalists believe in a supreme, universe-transcending creator whose single-minded, all-consuming focus is what people do with their genitals - a clownish, laughable notion deserving only ridicule. But even worse is the notion, held by millions of believers, that this being threatens humans: "Obey me or I'll hurt you!" This idea is a moral depravity that could only be born from wicked minds.

Any god worthy of the name wouldn't coerce its creatures' obedience through fear or pain, but would set up the world so that they would all freely choose through reason to do the right thing. That would be how a supreme intelligence would create; that would be a god of the neocortex. Instead, the religions of this world are stocked with clumsy, brawling, belligerent gods of the reptile brain - gods who are constantly bewildered and enraged when their plans go astray and who can think of no better tools than violence and destruction.

Religion is supposed to bring out the best in us, we're told by its defenders; it's supposed to encourage the decency and compassion that human beings are capable of. And perhaps, sometimes, it does do this. But more often, it gives vent to the violent, destructive side of our nature, gives us license to express our xenophobia and violence and rage under the illusion that these qualities are endorsed by God.

The Problem: According to Christianity and other monotheistic religions, pride is the deadliest sin. Taking excessive pleasure in yourself and your own talents and accomplishments is the surest way to end up condemned. I personally don't agree with the extreme view that pride is the worst possible character flaw - when properly harnessed, it's an important driver of individual effort and achievement - but I do agree that excessive pride is a problem common to human nature.

Most dictators and other evil rulers partake of an unhealthy amount of pride, believing themselves to be infallible and deserving of unlimited power. The same is true of fundamentalist religious leaders who fantasize that they've been personally chosen to deliver the will of God and force others to conform to it. When it goes unchecked, pride promotes the destructive view that society's elite aren't just more successful but morally superior, and that others are lesser beings whose needs are unworthy of consideration. Excessive pride promotes the dangerous delusion that the wealthy and powerful succeed solely because of their own inherent greatness, when the truth is that luck and circumstance play a much greater role in individual success than most people acknowledge.

The Solution: Christian authors often speak as if pride was a character flaw inherent to free will, one that not even God could get rid of. But the truth is that it's an entirely contingent fact of human nature. There's no reason why we have to have that tendency at all, and a truly omnipotent creator could simply have designed us so that we don't feel it.

Even Christian authors recognize that this is possible. Consider this passage from C.S. Lewis' The Great Divorce:

"It is up there in the mountains," said the Spirit. "Very cold and clear, between two green hills. A little like Lethe. When you have drunk of it you forget forever all proprietorship in your own works. You enjoy them just as if they were someone else's: without pride and without modesty."

The only problem with this scene is that Lewis thought this magical fountain was in Heaven. Why isn't it on Earth? Why doesn't all water in the world have the same effect? Or does God not want to eliminate pride from the world?

If you want a more concrete way of implementing this, here's my suggestion: design the human mind so that we don't feel a sense of ownership toward intangible qualities. The root cause of pride is that people feel possessive toward their own character traits, their own deeds and actions, in the same way that we feel possessive toward physical objects. They want to mark those things as belonging to me, not to the rest of the world, and praise themselves for possessing more of them than other people. But it's completely plausible to imagine a different psychology which would instinctively think it ridiculous that anyone could own something that can't be seen, touched, or held. People with this type of mind would still value intangible qualities like justice, compassion, or happiness, and want to see more of them in the world - they just wouldn't boast about how much of these abstract goods they'd acquired for themselves, and would value the existence of these qualities in others just as much as in their own lives.

The Real Explanation: The evolutionary roots of pride are murkier than more basic instincts like lust or selfishness, but I'd hypothesize that they have to do with sexual selection. Humans, like many species, compete with each other for mates. And when you want to convince a potential mate that you're a better choice than your rivals, the best way to do it is to boast (verbally or non-verbally) about all your positive qualities: how healthy you are, how strong you are, how high your standing is in the tribe, how faithful and true you'll be. The selective advantages to bragging about your virtues go hand-in-hand with the kind of brain that thinks of them as something belonging to me and not to anyone else.

Other posts in this series:

• Reengineering Human Nature

The Problem: Nearly all the world's religions teach that we should be generous to the poor and needy, and warn that greed and selfishness are destructive sins. "For the love of money is the root of all evil" (1 Timothy 6:10).

But this principle is rarely honored, even by the religious leaders who supposedly believe it. Catholic popes and bishops, as well as many Protestant preachers and televangelists, live in opulence and luxury and possess vast amounts of wealth: ornate mansions, private jets, multiple homes filled with art and treasure. Preachers of the "prosperity gospel" teach that God wants to make all their followers rich. Meanwhile, on the secular side, there are libertarians and acolytes of Ayn Rand who teach that selfishness is an unmitigated good and that all taxation and social programs are equivalent to theft and slavery. These influential apostles of greed have attracted huge followings and have contributed to a vast and growing gap between the world's rich and the world's poor.

The Solution: Clearly, the majority of human beings prefer getting to giving. But this isn't an ironclad law of human nature: Native American cultures of the Pacific Northwest had the custom of potlatch, where a person's standing in the tribe was set by how much wealth they could give away, not by how much they had for themselves. There are also modern philosophers like Peter Singer, who's argued that everyone should give away a quarter of their income or more to charity and who follows through on this principle in his own life; and businessmen like Warren Buffett, who's pledged to donate nearly all his multibillion-dollar fortune to charity. Examples like this are rare, but they do exist.

The traits of selfishness and greed are part of human nature, but the degree to which they're expressed is affected by the surrounding culture (the same is true, of course, for altruism and generosity). But there's no reason why the set point has to be where it is. Just as David Hume imagined the possibility of all human beings naturally being as diligent and industrious as the most devoted among us are now, we can imagine a world where human beings are naturally as generous as the most generous among us are now; a world where altruism is the norm, and cultures that value selfishness and greed are as rare as potlatch is in our world. Our brains could be wired so that giving away, rather than acquiring, is what gives us the most pleasure.

The Real Explanation: Human nature is forged by evolution, and in evolutionary terms, the success of the individual is all; more specifically, the success of the individual's genes. In a world of scarce resources, which describes the environment of our ancestors, there's little evolutionary benefit to extreme generosity, and potentially a strong benefit for selfishness. If my genes motivate me to give away resources I could have used for my own survival and reproduction, then I'll be less likely to survive and less likely to reproduce, and those genes thus will bring about their own disappearance from the gene pool. On the other hand, if my genes motivate me to be selfish and acquisitive and to get as much as possible for myself and my descendants, I'll be more likely to survive and to have healthy children, who will inherit my selfish genes and propagate them into the next generation.

Granted, this isn't the whole story. In a social species, it may benefit me to give away valuable resources to other members of my tribe from time to time. If I have more than I need and give away some of my extra (food, clothes, tools, shelter, mates), the recipient of my gift will owe me a favor, which I may be able to cash in some day when I'm in need. The potential benefits of this reciprocal altruism laid the evolutionary foundations for humans' sense of generosity. But all else being equal, evolution will always reward the individuals who keep as much as possible for themselves, which explains the dominance of our selfish side.

Other posts in this series:

• Reengineering Human Nature

I don't know if it's the warm weather here in New York that's bringing out the crazies, but these past two weeks, I've encountered more than the usual number of street preachers handing out loony religious literature. Because I know you wicked, godless atheists need to hear the word of the Lord, I thought I'd share some of the best examples with you.

This first one is my favorite. Last week, I was out on my lunch break when I saw a teenager standing on the street corner handing out fliers. He looked like an average high-schooler - baseball cap, T-shirt, baggy jean shorts, and a perpetual surly scowl - but when I took one of his pamphlets and glanced at the first page, I realized he was far more of a fanatic than I'd guessed:

You may remember that I wrote about Tony Alamo and his bizarre, greedy cult in 2009. When we last checked in with Mr. Alamo, he had just been sentenced to 175 years in prison for taking underage girls across state lines for sex. But apparently, being incarcerated hasn't dampened his high spirits. His ministry is still spewing its ultra-right-wing, frankly racist screeds, mixed in with a generous helping of loony Jack Chick-esque conspiracy theories (read the last column carefully and you'll notice it claims that the Vatican is behind Muslim suicide bombers).

But as you might expect of a man in Alamo's position, it's his current living arrangements that concern him the most. That's why the majority of this pamphlet - eight single-spaced pages - is a rant about how Mr. Alamo is a holy, selfless man whose only thought is of serving the poor, how he's been viciously persecuted by the government for no good reason, and how all his accusers are hateful, wicked people on a vendetta against him. Because, of course, Christians are such an oppressed and powerless minority in the U.S.A. The irony of titling his newsletter "The Alamo Christian Nation" while simultaneously claiming that the government unjustly persecutes Christians clearly hasn't occurred to him. (The awkward subject of Alamo's teaching that God approves of polygamous marriage to preteen girls, which is what he's actually in jail for, is politely ignored.)

Do you need more proof of Tony Alamo's pure and noble spirit? Just look at how the last page of the pamphlet describes him:

So, when I was handed this flier by Alamo's surly teenage follower, I couldn't help myself; I burst into laughter. "Isn't this guy in jail?" I said.

I'm guessing this was a sore point for him. "Yeah, on false charges!" he snapped.

Still laughing, I walked away. "Look into it!" he shouted after me. "I will," I called back jauntily.

And there's your update on Tony Alamo. My next encounter was even more amusing.

I was passing through Penn Station when I saw a stout black gentleman wearing glasses and headphones, leaning against a pillar with two handfuls of pamphlets which he was offering to every passerby. I took one, and noticed that the first page was familiar - it was a pamphlet I'd already gotten and written about once before - but there were others tucked inside of it which were new to me, though they all concerned the same general theme:

This is the handiwork of Family Radio, a network of Christian radio stations run by the evangelist Harold Camping, who's slowly been getting crazier over the decades and who's best known for his certainty that the Rapture will come in May 2011 (after his previous certainty that it would come in 1994). In case you're curious how he arrived at that conclusion, I've scanned one page of the interior. I recommend not operating heavy machinery after reading this brilliant work of exegesis.

The mindset of people who believe this sort of thing genuinely intrigues me, so I stopped for a brief chat with the fellow.

"May 2011," I observed. "That's soon."

"Uh-huh," he said noncommittally, clearly not sure whether I was making fun of him.

"What happens on that day?" I asked.

"The universe will cease to exist," he explained. He said it as calmly as if it was a weather forecast. (I have to admit, I was hoping for something a little more dramatic: boiling oceans, gouts of fire, that sort of thing.)

"What happens if that date comes and you're still here?" I persisted.

"I'll be in big trouble," he said calmly.

I wanted to correspond with him, if for no other reason than to see his reaction on May 22 (and maybe to give him some gentle guidance toward atheism, if he was reconsidering his faith at that point). I asked him for his e-mail address, but he claimed he didn't have one. "This is just the way I live now," he said. I don't know whether that meant he's divested himself of worldly possessions like computers to prepare for the Rapture, or if he just spends 24 hours a day handing out literature in the subways and so doesn't have time for e-mail.

I'm still looking for a devotee of Camping who's willing to speak with me. I think it'd make for an interesting conversation. If I can find one who's willing to go on the record, I'll be sure to let you all know!

The Problem: Many religions, including Christianity, teach that unjustified anger and violence are sins that risk the offender's eternal soul. The Ten Commandments order people not to murder - usually a crime committed in the throes of anger - while Jesus says that even a momentary outburst of anger can lead to damnation: "But I say unto you, That whosoever is angry with his brother without a cause shall be in danger of the judgment: and whosoever shall say to his brother, Raca [an Aramaic insult —Ebonmuse], shall be in danger of the council: but whosoever shall say, Thou fool, shall be in danger of hell fire" (Matthew 5:22).

But humans are violent creatures. Nations and peoples have been pitted against each other since the time of our oldest written records, and countless millions have died in the wars, invasions and rebellions that fill our history. Hunter-gatherer societies, often caricatured as peaceful savages, actually have even higher rates of murder and warfare than modern industrialized states. On the individual level, as well, there are millions of short-tempered people who think little of responding to any provocation with fury and violence. For most of human history, for example, and in many places still today, beatings were considered an acceptable method of keeping wives in line.

The Solution: Some human beings are natural pacifists, shunning war and violence. The question is, why aren't we all like that? Instead of giving us an impulse to violence and then commanding us never to use it, why wouldn't God simply create humans such that violence is unthinkable to us?

There are several plausible ways to implement this in human neural wiring, and the easiest one that I can think of is through the sense of disgust. Human beings have an intrinsic sense of disgust: we instinctively recoil from things like rotting food, diseased animals or excrement. This is an adaptation to protect us from disease and pathogens by making us physically nauseated at the thought of coming in contact with things that are likely to transmit them.

A creator with the freedom to design human psychology as he sees fit could have discouraged us from doing violence by connecting those circuits to the sense of disgust. With this change, the idea of doing physical harm to another person, whether up close and in person or at a distance, would fill us with revulsion and nausea and would make it all but impossible to actually carry out that impulse. (We could specify that this deterrent triggers based only on the intent of an action, not its effect, so it wouldn't interfere with doctors giving shots or performing surgery so long as they genuinely want their patient to get well.) Humans would then quickly find that diplomacy and negotiation, rather than bloodshed, would be the only feasible way to solve our disagreements.

The Real Explanation: The problem with this possibility, in evolutionary terms, is that it's an unsustainable equilibrium. If all people were peaceful and non-violent, and then one mutant appeared who could use force to get his way, the rest of us would be helpless against him and he and his descendants would rapidly outcompete us. There's no evolutionary advantage to the individual in being a pacifist. The benefits are only to the species as a whole, and natural selection doesn't work at that level. Thus we expect that evolution would make us violent animals, to defend ourselves from all the other violent animals who stand to benefit from doing the same.

Other posts in this series:

• Reengineering Human Nature

The Problem: According to the commandments of the major religions, God expects humans to have only a single lifelong romantic partner and to remain sexually faithful to them: "Thou shalt not commit adultery" (Exodus 20:14).

Yet, as any given week of tabloid headlines will tell you, humans aren't naturally wired for monogamy. Even after we're married or in a monogamous relationship, the sex drive continues functioning, often producing strong feelings of attraction and lust for people other than one's chosen partner. Even celebrities and politicians in high-profile relationships, people who have by far the most to lose from being caught cheating, seem unable to resist the urgings of adulterous desire. (John Edwards and Tiger Woods are the two most famous examples in recent headlines - by the time you read this, there will probably be others.) Religion also seems ineffective at restraining lust: consider the many high-profile preachers, from Jimmy Swaggart to Ted Haggard to Jim Bakker (and many, many more), who've been caught in heterosexual or homosexual relationships outside their marriage.

The Solution: It's utterly bizarre and inexplicable, on the theistic worldview, that God would create humans with overwhelmingly strong inclinations to commit an act he doesn't want them to commit, and then punish them harshly if they fail to resist the temptations he himself implanted in them. This view makes God out to be some kind of Kafkaesque sadist who doesn't want humans to be saved and delights in placing stumbling blocks in their path.

But it didn't have to be this way. If God is an omnipotent architect with the power to create any kind of beings he pleases, and if God's preferred model of sexual and romantic relations is lifelong monogamy and fidelity, it would have been easy for him to make that happen. Rather than creating human beings as we are now, God could have created a world of human beings with a different psychological makeup.

In this possible world, if entered into willingly, the ritual of marriage produces psychological and physiological change in the brain such that from that day onward, a married person experiences feelings of love and sexual attraction for only their chosen partner and no one else. The ability to feel platonic love, to form friendships and meaningful relationships based in mutual respect and admiration, would be unaffected, but the idea of falling in love or feeling lust for someone other than your partner would be as inconceivable as the idea of falling in love with a lamp or a table. In this world, adultery simply wouldn't exist, as there would be no desire to engage in it.

The Real Explanation: Human nature was not created by God, but shaped and instilled in us by evolution. And evolution, above all else, rewards reproductive success: the drive to have as many descendants as possible, to maximize the contribution of your genes to the next generation. This is not because evolution has some sort of moral preference for this behavior, but simply because living beings that act in this way will proliferate at the expense of those that don't, and therefore we're more likely to be descendants of the former rather than the latter.

That being the case, it's to be expected that many human beings become attracted to more than one person over the course of their lives. There's no evolutionary advantage to shutting down your sex drive, while there is an evolutionary advantage to mating with anyone who might be willing. (Natural monogamy does evolve, but only on rare occasions - usually when children need the full attention and nurturing of both parents to survive.) For this very reason, if human beings were wired as I've described above, this would be strong evidence against evolution and in favor of God's existence. But this isn't what we actually find to be true.

Other posts in this series:

• Reengineering Human Nature

"For the flesh lusteth against the Spirit, and the Spirit against the flesh: and these are contrary the one to the other: so that ye cannot do the things that ye would."

—Galatians 5:17

"In order to cure most of the ills of human life, I require not that man should have the wings of the eagle, the swiftness of the stag, the force of the ox, the arms of the lion, the scales of the crocodile or rhinoceros; much less do I demand the sagacity of an angel or cherubim. I am contented to take an increase in one single power or faculty of his soul. Let him be endowed with a greater propensity to industry and labour; a more vigorous spring and activity of mind; a more constant bent to business and application. Let the whole species possess naturally an equal diligence with that which many individuals are able to attain by habit and reflection; and the most beneficial consequences, without any alloy of ill, is the immediate and necessary result of this endowment."

—David Hume, Dialogues Concerning Natural Religion, 1779

In 2006, I said the following in "Putting Humanity on a Pedestal":

...in the modern era, the findings of psychology and neuroscience have revealed that our minds and personalities operate due to comprehensible, material causes, not due to divine influence or demonic possession. For the most part the forces of religion have not even felt this blow yet, though glimmerings of an emerging understanding can be seen in, for example, the furious denials among the religious right that homosexuality could have any kind of genetic basis. However, when the full import of these facts becomes clear, I believe it will cause an upheaval in the religious worldview even greater than that caused by the theory of evolution.

Since I first wrote that, I've been thinking some more about it, and I've come to the conclusion that this was, if anything, an understatement. With a little work, this could be one of the most important arguments in the atheist's rhetorical quiver, one that would give us a virtually unanswerable talking point against nearly every form of theism.

If you've spent any time reading apologetic literature, you've probably come across the theologians who conceive of human free will as a blank slate, a mathematical point lacking any internal structure, such that not even God could influence our decisions without canceling our free will altogether. Curiously, many of these same theologians also insist on a doctrine called original sin, which claims that our decisions are biased toward evil - a contradiction that usually seems to pass them by without notice.

That contradiction aside, it's easy to see why theologians insist that free will is a blank slate. They want to claim that God is good, yet there's a huge amount of evil in the world that needs to be accounted for. The easiest way out is to put the blame on humans: insisting that God endowed human beings with free will so that we could achieve genuine fellowship with him, but that we went astray and brought sin into the world (and some go so far as to blame all natural evil on human sin). This serves to justify continued belief in God as the creator of all things while still holding him guiltless for evil and suffering.

But this claim, as vehemently maintained as it is, is obviously wrong. As any observer of human nature knows, free will is not a blank slate. Human beings come into the world with an innate set of psychological predispositions, desires, and tendencies to act in certain ways. In short, there is such a thing as human nature. And this leads to the obvious followup question: If there is a god who created humans, and if he created us with a particular nature, why did he make the choice he did rather than creating us with a different nature?

This question takes on special importance when you consider that, according to the moral rules traditionally handed down by religion, God has created human beings with strong inclinations to do things that he doesn't want us to do (the original-sin idea again). For instance, he cautions us against gluttony, yet creates us with an appetite for rich, sweet, fattening foods. He enjoins us not to commit adultery, but gives us sex drives that are unpredictable and uncontrollable. He warns us against wrath, but creates short-tempered people who get irrationally angry. He threatens doom for homosexuality, yet creates people who have homosexual desires.

I've tried this argument on a few occasions, and what I've found is that most theists react with bewilderment. They fail to comprehend the question, or insist that humans are the only kind of creature God could possibly have created, or claim that God could not have improved us without making tradeoffs that would have resulted in an even worse outcome (the absurdity of applying the concept of "tradeoff" to an omnipotent being is something else that never occurs to them).

Well, I think we can help them out. In an upcoming series of posts, I'll propose a series of imagination-stretching exercises - thought experiments which show how human nature could have been different, in ways that would improve it without any negative tradeoffs. These changes, while not depriving us of free will, would lead to a world with a greater sense of morality and smaller amounts of sin - and after all, isn't that what we're told God wants?

Other posts in this series:

• Reengineering Human Nature