Tuesday, November 20, 2007

Intuition and Empirical Evidence

Kepler's Orbits

While recently doing research on astrology, I've come to the conclusion that there's no evidence that astrology can predict future events, or accurately describe someone's personality based on celestial bodies, beyond the vague generalities that can apply to anyone. But this leads me to a bigger question about why astrology is so compelling to so many people. Simply put, it has a common sense appeal, or an intuitive appeal primarily because it seems on its surface to be rather scientific. Moreover, celestial bodies can be observed and mapped and predicted mathematically.

But unfortunately, we can't always trust our intuitions in such matters. This is where empirical testing is necessary to pry apart what works from what doesn't. Consider these examples in scientific history of what seemed intuitively obvious (to some) but turned out to be mistaken.

In the late 1600s, King Charles helped establish the scientific organization, The Royal Society of London. He set the members of the organization with a tough question, asking “Why is it that when a glass is full to the brim, and you put a frog in the glass, the water does not overflow?” Well, the scientific minded members contemplated this question for some days until one experimental fellow filled a glass with water, placed a frog in it, and the water actually did overflow!

Aristotle made a common sense mistake that took until Galileo to remedy. Aristotle thought that a heavier object will fall faster than a lighter object. And of course a rock will fall faster than a feather, but once the objects being dropped are heavy enough that air resistance plays relatively no role, then the two objects will fall at about the same speed.

Aristotle believed that objects tend to seek their "proper place," and thus it is that lighter objects fall slowly because they have more lighter elements (air and fire) which tend to rise. On the other hand, heavier objects fall faster because they contain more heavier elements (earth and water) pulling the object down faster.

But Galileo showed that a heavier object and a lighter object will fall at the same rate by experimenting with rolling balls of different weights down inclined planes, in effect slowing down the effect of gravity and measuring the speed traveled with his primitive but useful water clock.

Johannes Kepler did some mathematical experimentation based on observation, and came to the conclusion that the orbits of the planets are eliptical, not perfect circles, which had seemed intuitively obvious.

This conclusion seemed so strange to Kepler that he was initially reluctant to accept it, since the idea of planetary orbits as perfect spheres goes back at least to the ancient Greeks. But he realized that, as counter-intuitive as it seemed, nothing could predict the movement of planets so simply as elliptical orbits.

In fact, even Galileo refused to accept Kepler's claim about elliptical orbits since it seemed to disagree with what he thought was common sense.

There may be times when it makes sense to trust common sense, and we would be fools to dismiss it completely. But in some cases it is best to test our beliefs against nature by seeking out empirical evidence through experimentation when we can. When intuition has failed some of the greatest thinkers in history, we would be wise not to fall into the same trap.



Thursday, November 15, 2007

Five Bad Evolutionary Designs


Have you ever seen those nature documentaries where the narrator describes how perfectly designed, say, the cheetah, the polar bear, or the chameleon is for its environment? Of course, calling an animal perfectly designed is just shorthand for saying that the slow processes of evolution have led to that animal's well-adapted features. Yet evolution hasn't always generated the best designs, or at least not the best from an engineering perspective. In fact, some features seem downright poorly designed. This should come as no surprise when we understand a little about how evolution works.

When new features evolve in a species, they tend to build on already existing features. They aren't built from scratch. It's just too costly for evolution to go back to the drawing board and start over. This explains why lungs evolved from the swim bladders of ancient fish. This also explains why dolphins don't move their tails from side to side like fish do. The up and down movement of dolphin tails was built upon the galloping motion of their land-dwelling four-legged ancestors.


From an evolutionary standpoint new features don't need to have the best possible design either. They just need to be good enough to allow the organism to live long enough to reproduce. The evolution of the human body is no exception. We have body parts whose design is wanting, but they've been good enough to keep our species from going the way of the dinosaurs. Consider the following suboptimal designs in the human body.

Design One: The Pharynx

The human pharynx is the part of the throat that begins behind the nose and leads down to the voice box. It does double duty as a tube for breathing and for swallowing. But when you're swallowing you can't breathe, and when you're breathing you can't swallow. That's why humans run a serious risk of choking if the pharynx doesn't close at the right time when eating.

Curiously, human infants under six months and chimpanzees don't have this problem. But infants and chimps can't talk, and without our uniquely situated pharynx we wouldn't be able to talk either. The evolutionary advantage of talking must have outweighed the risks of choking in our early human ancestors. All in all, it's not a bad tradeoff, but engineers could certainly come up with a safer design especially if they didn't have to build on preexisting features.

Design Two: The Birth Canal

The Bible says that God punished Eve and her female descendants with painful childbirth because she partook of the forbidden fruit. Presumably, childbirth would be a snap if not for that damned curse. And not only has pain long accompanied childbirth, but so has death. The rate of mothers dying during childbirth in the United States in 1900 was about 65% higher than it is today.

You could blame God, or Eve, or the serpent. Or you could point the finger at bipedalism--walking upright on two legs. This evolutionary innovation forced a smaller pelvis on us. But bipedalism isn't the whole story. Humans have evolved big brains, and we needed a big container to hold those brains. This is why human infants are born more premature and helpless than most other mammals. Babies need to get through the birth canal before their heads get too big.

Design Three: The Jaw

The human jaw has too many teeth for its size. Many people have no room for wisdom teeth (third molars) if they get them, and a lot of people's teeth have to fight one another for limited territory, leading to crooked teeth and orthodontists. Impacted wisdom teeth can result in serious infections, and before modern dentistry these late eruptors could be deadly. If you couldn't eat, you died.

There's no consensus on why human jaws got smaller, but the fossilized jawbones of our Homo erectus ancestors show that, compared to us, they had massive jaws with huge molars. Some scientists suggest that our small jaw may have evolved in response to eating smashed and cooked food, so that over time there was little advantage to having a bigger jaw. Other scientists implicate the deactivation of a gene responsible for large jaw muscles, which may have allowed for our skulls to take on a new shape providing more room for those big brains of ours. Either way, we're stuck with small toothy mouths.

Design Four: The Appendix

This is a case of a vestigial organ if ever there was one. The human appendix has no known function, except perhaps to put money in surgeons' pockets. About the size of a finger, this organ is located at the beginning of the large intestine. Undigestible food that enters the appendix is normally forced out by muscular contractions. But when it isn't, the result is a potentially deadly infection.

The appendix is related to a digestive organ found in many other vertebrates. This is the cecum (pronounced SEE-cum), and it's largest in herbivores, where it helps to digest plant matter. Since evolution isn't keen on cleaning up after itself, we're left with a useless and potentially life-threatening organ. In fact, NASA is so concerned about appendixes bursting in outer space that it's considering requiring appendectomies prior to future long-term missions.

Design Five: The Spine

The spines of four-legged mammals work well horizontally. But when the spine stands up vertically, as in humans, it creates a lot of pressure on the vertebral discs. These discs can become compressed and slip, causing herniated discs and all manner of back pain and expensive therapy.

Standing on two legs must have benefited our early hominid ancestors who first adapted the upright position. A brand new spine designed for walking upright would have been an improvement, but instead evolution had to work with what it already had. There's no consensus on what advantages walking upright initially provided, but a widely-held view is that it freed up the hands for carrying food and manipulating objects. That's not a bad tradeoff, considering that it now allows us to rub our aching backs.

Building Upward

While evolution has created some wonderful adaptations that really do seem like optimal designs, it hasn't always done so. This is because novel features aren't designed from the ground up, but built up slowly on already existing features. Where an engineer would start from scratch, natural selection builds on whatever foundations it already has. As Richard Dawkins once put it: "Natural selection is like a robot that can only climb uphill, even if this leaves it stuck on top of a measly hillock. There is no mechanism for going downhill, for crossing the valley to the lower slopes of the high mountain on the other side."

Saturday, November 10, 2007

Morality Comes from God?

Plato

Religions are powerful cultural institutions that provide structure and meaning in many people's lives, often by providing moral rules for how we ought to behave. And many fundamentalist Christians hold that God is the source of morality. But the idea that God is the source of morality, and only those who believe in God can be genuinely moral people is a pervasive, powerful, but ultimately mistaken idea.


On this view, God is the sole author of morality in that he makes actions right or wrong by his commands. Acting morally, then, is simply a matter of following God's commands. Behaviors such as lying, stealing, and killing are morally wrong because God forbids them. Likewise, actions such as telling the truth are morally right because God commands them. This view of the nature of morality is called the Divine Command Theory.


Over 2,300 years ago, Plato, in his dialogue The Euthyphro convincingly showed why the divine command theory creates problems. Supporters of the divine command theory claim that an action is morally wrong because God says it's wrong. In other words, behaviors such as killing and stealing are morally wrong because God makes them wrong by his commands. If God did not forbid us to kill and steal, then killing and stealing would not be morally wrong. Likewise, morally right behaviors, such as being honest, are right only because God says they're right. The problem with this view is that whether an action is wrong (or right) becomes completely arbitrary. God could have said that killing and stealing are morally right, and then those actions would be morally right. You might object that God would never say that killing and stealing are morally right. But why not? On the divine command view, killing and stealing were not morally wrong before God made them wrong by his commands. In other words, God did not first recognize the wrongness of killing and stealing, and then command us not to kill and steal. How could God recognize that killing and stealing were wrong if those actions weren't wrong to begin with? There would be nothing to recognize about those actions that make them wrong. Remember, on the divine command theory it is God's commands that make actions wrong, and they were not wrong before God forbade them. So, it seems that there can be no reason for God to decide to make killing and stealing wrong, and thus his decisions are arbitrary.


The way around this problem is to argue that God's commands don't make certain actions morally wrong. Rather, God sees or recognizes that such things as killing and stealing are wrong, and that's why he forbids them. By making this move, we get around the problem of God's commands being arbitrary, but in the process we're forced to reject the divine command theory. We're left with morality being independent of God in the same way that arithmetic is independent of God. God does not make it true that 2 + 2 = 4. Instead, he recognizes that it's true. Similarly, God does not make killing and stealing wrong. Instead, he recognizes the reasons that make killing and stealing wrong, and he forbids us to kill and steal because of these compelling reasons.


But notice that, because morality is independent of God, we can recognize the same reasons for not killing and not stealing that God recognizes, although our thinking is certainly slower. We recognize the irreversible harm caused by killing as a reason not to kill, and we recognize the unfairness of stealing as a reason not to steal. Because morality is independent of God, both the believer and the non-believer are in the same boat when it comes to making moral choices. So we can see that one does not have to believe in God in order to be a genuinely moral person.

Friday, November 9, 2007

New Book--in the works


After co-writing the pro-evolution book The Top 10 Myths about Evolution (Prometheus Books 2007) with Cameron M. Smith, I'm striking out on my own with a new book idea. This book aims to debunk a host of New Age beliefs.

I was quite impressed with all of the atheist books that have come out in the last few years, namely, The God Delusion by Richard Dawkins, God is Not Great by Christopher Hitchens, The End of Faith by Sam Harris, Breaking the Spell by Daniel Dennett, and God: The Failed Hypothesis by Victor Stenger. And once Dawkins' book made it to the top of the New York Times bestseller list, it was great good news for infidels, skeptics, and humanists.

The idea of writing an atheist book did cross my mind . . . for about ten seconds. But it occurred to me that Dawkins' success would spawn a host of philosophers--or those who have taken a philosophy of religion class--to write their own atheist books. Soon the market would be flooded with atheist books, and what once seemed like an impossibility--a successful atheist book--would again be an impossibility because there will be too many damn atheist books. And really, how many times can these same arguments be rehashed without getting old? I have the above five atheist books on my bookshelf, but five seems good enough for me, and I imagine it would be good enough for many others.

So I've decided to stay within the realm of belief, faith, and general credulity, but move outside of organized religion, focusing on so-called New Age spiritual beliefs. I've met a number of New Age believers who reject the traditional Christian idea of God, and are even agnostics or atheists, but who embrace all sorts of hocus pocus with no evidence to support their beliefs. I can admire some New Agers who were raised Christian and found the courage to reject those beliefs. But many just replace those old beliefs with new feel-good ones. It's as if some have traded in the Bible for astrology, or heaven and hell for reincarnation, or faith healing for homeopathy, and the resurrection with alien abductions.

Generally, I don't think that New Agers pose the same kind of threat to America that conservative Christians do. But there is a strong anti-science thread that runs through much of the New Age. Curiously, the distortion of scientific terminology to support New Age thinking does not help promote scientific literacy. We see this in talk of quantum consciousness, and energies in other dimensions, or how those who claim to have ESP can't perform their feats when skeptics are present with their negative vibrations, and so on. I see parallels between this form of scientific distortion and the views of so-called scientific creationists. Even though the targets and explanations are different, they're both attempts to make room for superstition with scientific-sounding terminology.

A few books have been written to debunk New Age beliefs, but not many in the last 10 years or so. But these beliefs are still with, as polls show that 34% of Americans believe in UFOs, 34% believe in ghosts, 29% believe in astrology, 25% believe in reincarnation, and 20% believe in alien abductions.

Right now I'm preparing two chapters and a book proposal which I hope to give to my agent by the end of December. At this point one chapter is finished, and I'm beginning work on the second.

It's my hope that many of the same readers who enjoyed the books debunking religion will also enjoy a book debunking New Age hocus pocus. Maybe I'll ask an astrologer if this idea is a good one or not.