WEIT: The Meaning of Life

At last we've arrived at the final chapter of Why Evolution Is True, and it's a short but sweet one. Coyne devotes these last few pages to a discussion on evolutionary theory's impact on society, and some of the common misconceptions that often arise from it.

We have plenty of evidence for evolution, plenty of fulfilled predictions, and no pieces of evidence (e.g. Precambrian rabbits) that would have disconfirmed it. Scientists disagree on minor points, like the importance of genetic drift or the precise cause of the Cambrian explosion, but there's no controversy on the big ones. So why is it that people find evolution so hard to accept? Most of the opposition comes from religion. Creationists create fear of evolution by claiming that it robs us of purpose, causes us to behave "like animals," and sanctions the killing of those who are weaker than us.

None of this is true. Evolution is a description of how life changes over time; it says nothing about whether such change is good or bad. It tells us how things are, not how they should be. It's not somehow "wrong" to defy natural selection by caring for the weak—that would be like saying that it's wrong to defy gravity by jumping or firing rockets into space.

Burn the heretics of our holy prophet Newton!

The idea that support for evolution would make us behave "like animals" is a non-starter. Animals exhibit an endless variety of behaviors, many of them altruistic. Perhaps creationists think that evolution would cause us to act like rhesus monkeys, who will starve themselves before allowing one of their companions to experience an electric shock?

Of course, it's true that humans have behaviors that are hard-wired as a result of natural selection: that's the realm of evolutionary psychology. Coyne criticizes this field for venturing too far into speculation, but he suggests eating, sleeping, sex, parenting and the favoring of relatives as uncontroversially inherited instincts. Another such instinct, the relative promiscuity of men compared to women, might seem to validate creationist concerns. But this behavior exists whether we accept evolution or not—and humans have higher mental faculties to override these urges and societies that can shame the cheaters.

What about purpose, then? How can we go on living without the notion that we were created by a loving God? Simple: we make our own meaning. We can love our friends and family, enjoy art, food and sport, and revel in the wonders of our universe. While evolution says nothing about meaning, it does grant us a vast appreciation for the extraordinary journey our species has taken to get to this point.

I think it would be appropriate to bring this series to a close with the quote from Richard Dawkins that begins this chapter:

"After sleeping through a hundred million centuries we have finally opened our eyes on a sumptuous planet, sparkling with color, bountiful with life. Within decades we must close our eyes again. Isn't it a noble, an enlightened way of spending our brief time in the sun, to work at understanding the universe and how we have come to wake up in it? This is how I answer when I am asked—as I am surprisingly often—why I bother to get up in the mornings."

JI: How Christianity Evolved (Part 2)

Yesterday I summarized how Jesus came to be viewed as the Messiah, and how early Christians became increasingly anti-Jewish despite Jesus' Jewish heritage and beliefs. Below I'll follow along with Ehrman as he explains the origins of Jesus' divinity, the triune nature of God, and the afterlife.

While it's now one of the cornerstones of the Christian faith, Jesus was not originally considered to be God. As evidenced by verses like Acts 2:22, 2:36 and 13:32-33, the earliest Christians thought he was a mere man whom God granted the status of Messiah at the resurrection. Later Jesus was thought to gain this title at his baptism (Mark 1:9-11), and then at his birth (Luke 1:30-35). Finally in John we see the fully developed view of Jesus' eternal existence as God himself (John 1:1-14).

Ehrman says that this increasingly deified view of Jesus developed independently in different places. Based on details like the "we" in John 21:24-25, John may have been written by a Jewish community, who rationalized the rejection of friends and relatives by assuming they had special access to the truth of Jesus' divinity. Others began believing that Jesus was divine based on his "cosmic judge" position as the Son of Man, while still more drew this conclusion from the fact that both Jesus and the OT God used the title of "Lord." And among former pagans, who were used to demigods born of a god and a human (e.g. Heracles), perceiving Jesus as God would have been easy.

The Trinity doctrine developed to solve the problem of how Christianity could continue as a monotheistic religion. The Ebionites decided that Jesus was not God, the Marcionites concluded that the OT God and the God of Jesus were two distinct entities, and the Gnostics thought Jesus was one of many divine beings. However, the two most popular doctrines were modalism, where God is one being who expresses himself in three roles, and Arianism, where God is one "substance" with three distinct persons. Even after Arianism won out, some insisted that the Son's position must be inferior to the Father's. But in 325, the modern view of Father, Son and Spirit as equal persons of the divine substance (problematic as it may be) was established.

Neither Jews nor the earliest Christians believed in immortal souls, heaven or hell. The OT prophets simply believed that God would inflict earthly punishment on those who sinned against him. The apocalypticists, such as Daniel, Jesus and Paul, believed God would come to judge the world and set up a new kingdom on earth, in which those who were dead would be physically resurrected. But when Jesus didn't come back as expected, people had to resolve their cognitive dissonance by reinterpreting this view. This is especially evident in 2 Peter, whose author desperately tries to explain that "with the Lord one day is as a thousand years." Eventually the judgment was reworked so that it came, as Ehrman puts it, "not at the end of the age but at the end of one's life," when one is sent to either heaven or hell.

The fact that Christian doctrines changed significantly over time does not in itself mean that they're false. But I agree with Ehrman when he says that their formation process looks distinctly human: it's full of fierce disagreements, political struggles and flimsy rationalizations. I would never expect such chaos and illogic if God, the perfect communicator, were truly in control.

JI: How Christianity Evolved (Part 1)

It would surprise many Christians to learn that the beliefs of the very early church were totally different than those of modern times. If a Baptist preacher could go back in time and interview Christians from around 50 CE, he would find their views on the afterlife or Jesus' relationship to God and Judaism to be not just unusual, but completely heretical. In the seventh chapter of JI, Ehrman covers how Christian doctrines developed to become what they are today.

The first issue is that of how Jesus came to be seen as the Messiah. Ehrman points out that the Jews were expecting the Messiah to be a powerful king that would rise up to destroy their enemies or a cosmic judge of the world, based on the authority of Old Testament prophecy like Psalm 2:1-9 and Daniel 7:11-14. But Jesus could hardly have failed more spectacularly to fit this mold: he was a little-known, harmless itinerant preacher who was effortlessly crushed by the Roman Empire.

Uh, yeah, we're pretty sure you're not our guy.
We're gonna go ahead and wait.

So how did Christians come to view Jesus as the Messiah? After they became convinced that he had risen from the dead, their view that he was the Anointed One was cemented. All that was left was to reinterpret the OT. They explained away the "king" prophecies as spiritual, decided that any OT bits that happened to vaguely fit Jesus' life were prophecies, completely fabricated details of his life to fit other prophecies, and presto! Instant Messiah.

Another trend in the early church was the rise of anti-Semitism. Given that Jesus and his disciples were Jews, and that Jesus preached that people should repent according to Jewish law before the imminent apocalypse, this seems bizarrely inconsistent. However, as time passed, Christians reinterpreted Jesus' message, became frustrated with Jewish refusal to accept him as Messiah, and even began blaming them for his death. John's gospel calls Jews the "children of the Devil" (John 8:37-44), the bishop Melito repeatedly accused them of murdering Jesus, and Justin Martyr wrote that circumcision was meant to set Jews apart as worthy of persecution. This marked the first time that Jews were singled out as a persecuted minority—and it led to many others throughout history.

This chapter is a long and detailed one—not surprising given that this is Ehrman's particular area of expertise—so I'll stop here for now. Tomorrow I'll cover how the views of a divine Jesus, the Trinity, and the afterlife developed.

LY5: Why Creationism Isn't Taught

Like one of my previous posts, this one is inspired by the subreddit r/ExplainLikeImFive, which attempts to give useful explanations to complex issues on a grade-school level. What's surprising is that these explanations are fun to give, and well-written ones are fun to read even if you're already familiar with the topic. Some people might find them condescending, but personally I think they're endearing and often astonishingly accessible.

To most non-creationists it's pretty clear why creationism has no place in public schools, but here are the reasons, explained like you're five.

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There are two basic reasons why creationism isn't taught in public schools.

The first reason is that creationism is a religious belief. It says that the universe and all life on earth was created by God. But in America, one of our guiding concepts is separation of church and state, meaning that the government is not allowed to endorse religion—including in public schools, which are run by the government. Some creationists decided that they wanted to make their ideas look like they weren't religious, so they came up with intelligent design (ID).

ID says that the universe and all life on earth was created by some very powerful being, but doesn't speculate on what that being might be. But here's the problem: most of the major ID supporters are Christians who are trying to use it to promote Christianity. It's basically just religious creationism in disguise, which is exactly what a judge ruled in an important 2005 court case. But what if ID weren't being pushed for that reason? Then it wouldn't necessarily be religious, so could we teach it in schools?

That brings us to our second reason: even leaving the issue of religion aside, creationism (including ID) can't be taught because it isn't scientific. A scientific theory needs to be testable. It needs to make specific predictions about what we should expect to see if it were true, and it needs to be capable of being proven wrong if we don't see those things.

But without some details about this intelligent being—its traits and behavior—we have no way of predicting what kind of impact it would make on the world. And let's say we do make up a prediction: maybe a designer would create the best possible life forms. If this is proven wrong (say, by poor design), ID supporters can just say that maybe the designer behaved some other way instead. The "best" solution that supporters have come up with is probably specified complexity, but that's not saying much: it's a vague, deeply flawed attempt at telling apart designed and undesigned objects that has never actually been useful in practice.

So there we have it: creationism isn't taught because it's both religious and unscientific. Many people naively think that we should be "teach both sides" in the interest of "fairness," but that would be no more "fair" to students than teaching astrology in an astronomy class. Of course, the creationist movement could be mentioned as a historical footnote in a course on world religions or American politics, but that's a different matter. As far as the science classroom goes, it's been rejected twice over, and rightly so.

WEIT: The Naked Ape

This is why the "no transitional fossils"
canard just makes me laugh.

Coyne begins WEIT's penultimate chapter by expressing the cultural and religious importance of human evolution. Even many religious people and institutions that otherwise except evolution (the Catholic church, for example) still reject the notion that humans could have evolved from other primates. Incredibly, John Scopes was convicted of the crime of teaching such facts less than a century ago, in 1925. Because of the potential public outcry, Darwin barely mentioned the issue in the Origin, and another scientist reburied the bones of a Homo erectus specimen for 30 years.

Thankfully, though, we have a decent understanding of our lineage today. Our evidence includes things like homology and genetic data, but fossils are the focus of Coyne's chapter. Here's what we should expect if humans evolved:

"Around five to seven million years ago [based on molecular evidence], we expect to find fossil ancestors having traits shared by chimpanzees, orangutans, and gorillas, but with some human features too. As the fossils become more and more recent, we should see brains getting relatively larger, canine teeth becoming smaller, the tooth row becoming less rectangular and more curved, and the posture becoming more erect. And this is exactly what we see."

To summarize (and ignore over a dozen other important finds): First comes the 6 to 7 million year old Sahelanthropus tchadensis, possibly our last common ancestor with chimps, which has a long skull and small brain like apes, but a flat face, small teeth and brow ridges like later species in our lineage. Then there's Australopithecus afarensis, of which Lucy is one. We know they were bipedal because their femurs angle inward from the hips, making upright walking far more efficient. They may even be responsible for the 3.6 million year old Laetoli footprints.

At this point, brain sizes begin growing steadily. Homo habilis, from about 2.5 mya, still have some apelike characteristics, but also have larger (though not human-sized) brains and have been found with carved stone tools that would be used for things like butchering. Homo erectus "still had a flattened, chinless face," but used even more complex tools, along with fire for cooking. Finally, just a couple of hundred thousand years ago, we have Homo neanderthalensis, distinct from but extremely similar to modern Homo sapiens. We most likely wiped out the Neanderthals either by outcompeting them or killing them.

While these fossils finds are more likely to come from close evolutionary cousins than our direct ancestors, they still tell us an enormous amount about our history. Anyone who looks honestly at the fossil evidence (let alone things like DNA and vestigial organs) would conclude, as modern science has, that we have a common ancestor with the other great apes. Coyne drives this home with one particularly amusing yet compelling point. Creationists who look at the evidence must classify all fossils as either apes or humans. If we really are a distinct creation of God, this ought to be a simple matter, but here's what happens when they try:

Via TalkOrigins

They can't even agree amongst themselves.

As a questioning creationist investigating the evidence for evolution, the image above blew my mind. Self-proclaimed creationist experts like the infamous Duane Gish confidently asserted that there are no human transitional fossils. Yet ironically, their classifications of various fossils follow a gradient from "apelike" to "humanlike" that beautifully confirms the evolutionary paradigm. Some individuals can't even decide whether a given fossil is ape or human, while others have changed their minds. Their willful blindness to the obvious conclusion is, frankly, fascinating.

Coyne goes on to address a few other interesting topics, including a thorough debunking of evolutionary racism: we diverged only about 80,000 years ago—not enough time for any major disparities to develop—and most differences between races are physical, the result of differing climates and sexual selection. Most of the rest isn't relevant to this blog, though, so instead I'll sign off with an informative chart of growth in hominid cranial capacity over time:

How anyone can group these into "ape" and "human"
with a straight face is beyond me.

Parsimony, Explained Like You're Five

Reddit.com has a great new community called r/ExplainLikeImFive, where you can ask questions and get informative yet simple answers. This is useful not only for people who want to learn tough concepts without fear of judgment, but also for the explainers themselves: nothing tests the depth of your understanding on a topic like having to break it down so thoroughly that a 5-year-old gets it.

Recently someone asked for an explanation of Occam's razor. Below is my answer (and if it's not obvious how it pertains to this blog, just replace "monsters" with any instance of the supernatural).

*      *      *

You know those bumps you hear sometimes when you go to sleep at night? Let's try out a few ways of explaining them.

Maybe your parents are making those noises when they close a door or bump into a wall. Or maybe those noises are from the house settling. When the air gets cooler at night, the wooden beams in the ceiling contract, which causes them to make little bumping sounds.

Or maybe there are monsters lurking in your closet, rapping on the walls, letting you know they're waiting for the right time to strike.

Bump. Bump. Bump.

Sorry, didn't mean to scare you.

Anyway, the point is that the "parents" and "wooden beams" explanations are better than the "monsters" explanation because they're more parsimonious, which you can think of as a fancy word for simple. Really, though, it's more than that: parsimonious explanations need less assumptions, less complicated extra stuff added on to have everything make sense.

True, the wooden beam explanation is more "complicated" in the normal sense, and it's "simpler" in the normal sense to just say "monsters did it" and leave it at that. But it turns out the opposite is true when you really look closely.

You can do experiments to find out that wood really does expand when it gets colder. But what about those monsters? Your parents checked the closet for you before they turned out the lights, so how exactly did they get in there, anyway? Hmm. Maybe they're invisible, and your parents just didn't see them. But then the next night you can have them feel around in there, too. Well, maybe the monsters can make themselves solid or unsolid at will. Now you've finally made everything in your explanation fit. But look at what you've had to do: you've had to assume not just monsters, but two pretty unlikely things about those monsters. It turns out that this explanation was more complicated after all.

Occam's razor says that all else being equal—that is, if all the other conditions (e.g. whether your parents are home) stay the same, and if the explanations are equally good in all other ways—more parsimonious explanations are more likely to be right. And this makes perfect sense: every bit you add onto your explanation can only make the odds of it being true go down, not up—just like the odds of rolling three 6s in a row on a die is lower than the odds of rolling two 6s in a row.

This idea is useful in pretty much any case where you need to choose between explanations: science, history, and even everyday life. It's a cornerstone of rational thinking. You've probably used it many times without even realizing it, but now that you understand it, you can apply it even more often and more carefully, and get results that are more likely to lead you to the right answer.

The Bolted Door

Don't let your mind be a prison.

My first few whispers of doubt about Christianity began during my later years of high school, but what I haven't yet mentioned was my peculiar reaction to these feelings. I could have been curious about my doubts, or even frustrated with them, but instead I was afraid of them.

Why would doubts inspire fear? Because if they led me astray I would suffer an agonizing eternity in hell. So, I figured, why risk such a horrible fate at all? The easy solution was to suppress these doubts for the sake of securing salvation. This is why hell is surely the most powerful tool that Christianity has at its disposal: not only does it cause people to convert in desperation, it makes questioning dogma the most dangerous thing one can do. It produces vast quantities of intellectual dishonesty by causing people to value the adoption and preservation of certain beliefs over truth itself. (If it's not obvious why truth is a valuable goal, this post from Eliezer Yudkowsky may be of help.)

Perhaps I implicitly sensed the direction in which I was heading, because at times I imagined some future version of myself who no longer believed: a hazy figure, grinning, wreathed in shadow. Not evil, necessarily, but somehow turned over to the dark side, hopelessly misguided, a heathen and proud of it. I was determined not to become this person. At that time, of course, my perception of nonbelief was seriously warped. As far as I can tell, my life isn't enveloped in some kind of spiritual darkness, and if I'm misguided, I can at least take solace in the fact that I've honestly and carefully sought the truth.

For over a decade, it never even occurred to me to take a skeptical approach to my faith. But for a few years after that, I stuffed the skeptical outlook away behind a bolted door in my mind, guarded fiercely by images of fire and brimstone. It's both surreal and sad to think that I once consciously feared becoming the person I am today. And in response, I have resolved not to fear the possibility of being religious again in the future. I'll use logic and critical thinking to examine the information that comes my way, and I will accept whatever conclusion follows. It's a mentally demanding way of approaching the world, but when you follow this principle, truth prevails.