I hope that I’ve presented a compelling argument for evolution so far, which would by default also present a compelling argument against young-earth creationism. What I haven’t addressed yet is intelligent design, and for good reason. Intelligent design is a tricky think to pin down; it means different things to different people, from a “dba
” for creationism to what is essentially evolution with a prime mover (which is, I believe, the Catholic stance). Since I’ve already addressed creationism, for the purpose of this essay I’ll treat intelligent design as “intelligent evolution” – that is, evolution with a deific catalyst and guiding hand. I’ll treat the god involved as a stand-in for the Christian God, who has the properties of being all-knowing, all-powerful, and good. The arguments against a demiurge like Gaia, Ptah, or Marduk are more difficult to address, since you need to be able to definitively list the attributes of a god to present counter-evidence.
I’ve also avoided intelligent design so far because I don’t think it’s diametrically opposed to evolution, and evolution was meant to be the scope of the essay. You can be convinced of evolution and still be a good Christian. You can be convinced of evolution and still be a good many things; since the theory of evolution doesn’t speak to abiogenesis or the origin of the universe or ethics, or even body-soul duality. But I think that that once a person has made a study of evolution and accepted the basic tenets, they can make arguments – convincing arguments – against a deistic demiurge. Consider this chapter, if you will, an appendix to the rest of the essay.
I think it’s important first to give attention to what I believe are the primary arguments for intelligent design (and if I’m presenting them unfairly or missing any substantial arguments, as always please let me know!): The fine-tuning of the universe, and the Watchmaker hypothesis.
The fine-tuned universe (http://en.wikipedia.org/wiki/Fine-tuned_Universe) theory suggests that the fundamental physical constants (the speed of light, the size of the electric charge of the electron, the relative mass of electron to proton, etc.) are tuned to a very narrow band, where altering them even by a couple of percentage points would preclude the possibility of life as we know it. Stars would not form, so heavier elements like oxygen and carbon (much less iron) would be incredibly scarce, and there would be no chance of finding protein, much less life.
There are a three significant responses:
First, that the universe isn’t as fine tuned as we’ve been led to believe, at least from a cosmological perspective (http://en.wikipedia.org/wiki/Fine-tuned_Universe#Disputes_on_the_extent_and_existence_of_fine-tuning) The “goldilocks” bands in these constants within which stars could form is quite a bit wider than has been claimed, and once you have stars performing fusion you get heavier elements, and the rest is abiogenesis and evolution. Of course, this response is based on mathematical models and not practical experience (nobody is running around varying universal constants in laboratories and trying to spark stars into existence), but so is the original claim.
Second, if the universe is fine-tuned, it could be the expected result of cosmologically-scaled evolution. Just as species tend to produce viable offspring (or they wouldn’t be species for long!) universes produces viable baby universes. This argument relies on the concept that black holes are spouting baby universes in new dimensions, which is questionable at best. Still, the fine-tuning mentioned is actually tuned to create stars; carbon-based life is only an interesting by-product. Stars beget black holes, and black holes beget universes with the same constants as the parent universe (excepting, perhaps, some cosmologically-scaled genetic mutation). Thus, our universe exists with the constants it has because universes with those constants are most likely to reproduce. Purely in terms of statistics, we’re most likely to find ourselves in a universe that can sustain stars, and thus life.
The third response says, “Of course we find ourselves in a universe that’s able to sustain life, if we didn’t, we wouldn’t be having this conversation, would we?” This is generally referred to as the Anthropic Principle (http://en.wikipedia.org/wiki/Anthropic_principle). This response recalls the statistical discussion in a previous chapter about the likelihood of your parents producing you – the chance you’d come out as you are is astronomically small, but you were going to be like somebody one way or the other, and the you that popped out won the lottery, so it’s too late to argue now. Douglas Adams had an amusing take on how this concept of fine-tuning works (as quoted by Richard Dawkins):
… imagine a puddle waking up one morning and thinking, ‘This is an interesting world I find myself in, an interesting hole I find myself in, fits me rather neatly, doesn’t it? In fact it fits me staggeringly well, must have been made to have me in it!’ This is such a powerful idea that as the sun rises in the sky and the air heats up and as, gradually, the puddle gets smaller and smaller, it’s still frantically hanging on to the notion that everything’s going to be all right, because this world was meant to have him in it, was built to have him in it; so the moment he disappears catches him rather by surprise. I think this may be something we need to be on the watch out for.
The watchmaker analogy is an argument for the existence of a creator god that is at least as old as 1686, but is quoted most commonly in the words of William Paley:
In crossing a heath, suppose I pitched my foot against a stone, and were asked how the stone came to be there; I might possibly answer, that, for anything I knew to the contrary, it had lain there forever: nor would it perhaps be very easy to show the absurdity of this answer. But suppose I had found a watch upon the ground, and it should be inquired how the watch happened to be in that place; I should hardly think of the answer I had before given, that for anything I knew, the watch might have always been there. (…) There must have existed, at some time, and at some place or other, an artificer or artificers, who formed [the watch] for the purpose which we find it actually to answer; who comprehended its construction, and designed its use. (…) Every indication of contrivance, every manifestation of design, which existed in the watch, exists in the works of nature; with the difference, on the side of nature, of being greater or more, and that in a degree which exceeds all computation.
But the watchmaker analogy is not really an argument; it’s a rhetorical device meant to establish the plausibility of the statement that you can tell, simply by looking at something, whether or not it was the product of intelligent design on the basis of its orderliness versus complexity. Ignoring the obvious problem of the teleology of a watch versus that of a human, the problem with this argument arises when it is applied as equally to vestigial structures and other evolutionary quirks as to items of so-called “irreducible complexity” (“so-called because of the previous chapter’s discussion). Consider, for example, the number of vestigial features in humans. Just a starter:
Goose bumps (http://en.wikipedia.org/wiki/Goose_bumps#Anatomy_and_biology) are an involuntary reflex to cold or strong emotion. In other mammals, goose bumps have the useful feature of making the creature appear larger, or of trapping an insulated layer of air against the skin. In humans, there is no benefit. In fact, the feature is uncommon on our head and genitals, where we actually have hair.
Jacobsen’s organ (or the vomeronasal organ; http://en.wikipedia.org/wiki/Jacobsen%27s_organ#In_human_beings) is the chemoreceptor in the nose of many mammals that allows them to detect pheremones. There is still some debate over whether the organ exists in adult humans (though much less over whether it exists in fetuses, then atrophies), but there is agreement that there are no nerve pathways to the brain in humans – that is, even if it remains unatrophied in adults, it can’t be used. The area of the gene that codes for it has become non-functioning in humans.
Darwin’s tubercule (http://en.wikipedia.org/wiki/Darwin’s_tubercle) is that little point on the back of your ear. In humans it has no function; in other mammals it provides necessary structural support for a pointed ear. Meanwhile, it’s worth noting that just as many mammals have muscles that allow them to move and rotate their ears, so do humans. In the case of (most) humans, however, those muscles are atrophied, connect to nothing, and are non-functional.
The plantaris muscle (http://en.wikipedia.org/wiki/Plantaris_muscle) that runs under our foot is a very useful muscle for primates that grasp with all four limbs. In humans the muscle is so atrophied it is frequently mistaken for a nerve by medical students, and so useless that it is generally the first thing to be harvested for tendon reconstruction elsewhere in the body. The palmaris muscle is a similar structure in our hands.
The third eyelid (or nictitating membrane; http://en.wikipedia.org/wiki/Third_eyelid) is the transparent third eyelid common birds and reptiles that provides their eye protection from flailing prey and moisture during long staring sessions, but without cutting off vision. It’s found in some mammals as well (camels, polar bears, and seals, for example); dogs and cats have them, but theirs are not well-muscled, so you usually only see them when the animal is waking up from sleep. Humans also have a vestigial remnant of this third eyelid, but it’s functionless.
The male nipple. I’ll just leave that there.
Our five toes – or, specifically, our fifth toe appears to be a vestigial feature. It’s an extra thing to be broken or at least stubbed (as I reminded myself this morning), yet removing the pinkie toe doesn’t cause any loss of functionality or balance, and quite a few people put almost no weight on that toe when they walk. It’s a liability. Most other walking creatures have only four toes on the ground (consider the near-ubiquitous dewclaw in quadruped mammals – another example of vestigiality), but primates who grasp with their foot find their fifth toe as useful as we do our pinkie finger. And since our ancestors were primates, we get a fifth toe.
Likewise, the coccyx (or tailbone) is vestigial in humans, and a small number of people are borne with atavistic tails in its place. While the coccyx still has nine muscles attached to it, including one necessary for defecation, these can be successfully reattached to the sacrum with no loss of functionality (something, presumably, an intelligent designer could have done easily). What do we get for having a coccyx? Only the very painful possibility of a fracture.
Going back to our watchmaker analogy, what would you say, upon opening a watch, if you found mounting points for a different type of mechanism, gears with unused ratios, or a gap where previous models had used a winding spring instead of a battery? Probably nothing, because we’re used to this kind of re-use – it’s cheaper, it’s easier and it allows the manufacturer to save on the costs of retooling parts and redesign. But what kind of god does this? An all-powerful god, for whom a new design is no more difficult or costly than re-use? A god who sees the future and the end of all things, but fills our anatomy and genome with countless dead ends? Is it fair to call this god “lazy”? Was this god busy with something else, or disinterested? Are this god’s eyes truly on every sparrow? Aside from a brief mention of ERV’s in a previous chapter, we have not even addressed the cases where inclusion of these vestigial features poses us a real danger.
Think of our wisdom teeth, which helped our pre-agricultural ancestors chew cellulose – plant fibers in grass and leaves. When you have a diet like that, the more teeth the better! But our modern jaws aren’t as large as those of our ancestor species, so we run into the problem of impacted wisdom teeth. Estimates on the number of Americans with at least one impacted wisdom tooth run as high as 90%; extraction of wisdom teeth is now a routine procedure. Pain is generally the worst problem a person with an impaction is likely to face these days (with our better dental hygiene), but in the past the combination of partial eruptions and caries could lead to advanced tooth rot (and potentially fatal complications), and that does not count the (smaller) possibility of developing a malignant tumor at the site of the impaction (about 1-2% of all impactions, per wikipedia: http://en.wikipedia.org/wiki/Wisdom_tooth).
Think of your appendix, which also seems to have been useful in the past for digesting cellulose. (There are some claims that the appendix plays a role in our immune system, but this is not born out in decreased immune function among those who have had an appendectomy.) Acute appendicitis has a high mortality rate, and it affects about 7% of Americans over the course of their lifetime.
Were these oversights on a creator god’s part, or was that god worrying more of our plant-eating ancestors than modern humans? These might sound like sarcastic questions, but they are serious. What would you think of a human designer proposing these same features? So, If the watchmaker analogy holds, what do these kinds of designs say about the designer?
Consider the route of the vas deferens (http://upload.wikimedia.org/wikipedia/commons/0/08/Route_of_vas_deferens_from_testis_to_the_penis.png), which rises up from the testes to loop over the ureters, then descend past the bladder to the penis. In our ancestor species, the testes were internal (that’s the case for most mammals and other animals in general); as they descended to their modern external location, the vas deferens was “hooked” on the ureter, like a leash is hooked on a tree when a dog and its owner choose to walk on different sides. Would not a creator god have prevented this complication, and prevented subsequent cases of infertility and ureter obstruction (and subsequent infection?)
Consider, too, the route of the recurrent laryngeal nerve (http://en.wikipedia.org/wiki/File:Gray622.png), which allows us to speak (and allows other animals to vocalize). It leaves the brain, travels all the way down the neck, loops under the aorta, then travels back up to the larynx, taking more than a foot to accomplish what the superior laryngeal nerve does in inches. (Note especially the image here: http://www.icr.org/article/recurrent-laryngeal-nerve-not-evidence/). This is common in all mammals, so as you might imagine, in giraffes this creates a nerve pathway nearly fourteen feet longer than it needs to be! The second link above, as well as http://creation.com/recurrent-laryngeal-nerve and http://www.evolutionnews.org/2010/10/the_recurrent_laryngeal_nerve_039201.html argue that this is not bad design, because this nerve also enervates the heart and trachea along the way (though they do not address why it wouldn’t be a better design for the vagus nerve to enervate those, since it’s going down there anyway, or for the laryngeal nerve to continue on that way after passing the larynx, rather than looping back to make the larynx the final destination), or because redundant pathways provide backups (though they do not address why a simple left-right redundancy would not suffice, or that a looped pathway provides multiple points of failure to a critical organ), or because human circuit design is frequently circuitous (though they do not seem to realize this exposes their god to claims of limited resources or lazy design). From a strictly evolutionary viewpoint, the route makes sense. Our distant ancestors, fish, have no larynx or even a neck, but they use the same nerve to enervate their gills. As the laryngeal function developed in the trachea, it is understandable that nerves which serve the respiratory system would continue to serve new features there; the unfortunate consequence in mammals is the location of the voicebox at the top of the throat and a nerve that couldn’t come untangled from the aorta. Would not a perfectly intelligent designer have foreseen this consequence and disentangled them to begin with?
One could argue that the ways of a designer are mysterious and beyond our comprehension, but what does that tell us? If we were made in the image of the designer even on a metaphorical level, should not the watchmaker analogy hold, and we would recognize both excellent and poor design? Wouldn’t we expect to see upright human posture supported by a spine and bones ready-made for such a position, rather than an unstable adaptation from a quadrupedal posture? (http://www.fireandknowledge.org/archives/2007/12/22/our-imperfect-backbone-miller/) Or does the watchmaker analogy fail, and we cannot differentiate intentional design from evolutionary “mistakes”?
Evolution’s design is an emergent quality of semi-random events, so it makes sense both that we’d see re-use of homologous features like the pentadactyl limb and complete redevelopment of the same feature (like eyes, which have evolved independently at least fifty different times (http://en.wikipedia.org/wiki/Evolution_of_the_eye, and sometimes better than others). Why would a creator god choose to cobble a panda “thumb” (pronounced as “wrist-spike”) from of a sesamoid bone (http://en.wikipedia.org/wiki/Sesamoid_bone#Panda_anatomy) rather than just giving the panda the articulating opposable digit already available in other creatures that need to grasp?
Any of these arguments, taken individually, could be marginalized, but I hope I’ve presented a sufficient number of them to establish a pattern – a pattern whose reasonable conclusion requires increasingly complex logical gymnastics to avoid. These may not constitute an argument against gods in general, but in general it’s impossible to conclusively prove the non-existence of a thing. (That holds for both gods and celestial teapots (http://en.wikipedia.org/wiki/Russell%27s_teapot).) What I hope I’ve done is show that if a creator god is assumed to have the certain characteristics of the Christian God, the evidence that suggests naturalistic evolution overwhelms the evidence that suggests intelligent design by such a god.
In closing, think for a little bit about the size of the universe – really think about it. As many times as I do it, it’s still mind-boggling. http://www.youtube.com/watch?v=17jymDn0W6U. About the biggest number I can deal with in my head is the number of people in a packed stadium – say about 40,000 people. That’s about the population of a moderately-sized city, or more than 250 times the number of people a person can reasonably be expected to interact with and know (http://en.wikipedia.org/wiki/Dunbar’s_number). You need a block of these packed stadiums, five long and five deep, to hold a million people. (Already my mind’s grasp on the scale is beginning to slip.) You need 7,000 such blocks blocks (think 70 wide, 100 deep) to hold the number of people living in the world today. That’s just people. We may be pretty smart, and we may have a massive impact on our planet, but there are probably about 100,000 ants alive for every human alive. And that’s not even counting whales and horses and three-spined sticklebacks and all of the other multi-cellular creatures. There’s lots of those. So that’s a huge number, but just a drop in the bucket compared to the number of bacteria, which is probably around five million trillion trillion (or five with thirty zeroes after it). That’s a huge number, but that’s just Earth, which is just one rock orbiting a pretty unremarkable star. Back of the napkin math suggests that there are one hundred stars in the universe for every grain of sand on every beach on Earth.
How can we even begin to take seriously any theory that suggests we’re the center of things?