I was walking along the beach one day when I spotted a pair of strange creatures lying on the sand. One was covered in brilliant pink fluff. It had two legs and strange flattened arms without fingers. The other looked similar in shape, but without legs, and it was instead covered in strangely smooth red skin. I first approached the pink fluffy one. It seemed like a normal animal in most ways: It had two eyes, a mouth, nostrils. It hopped around a little, and made a high jump, flapping its arms to push itself up the last few inches. I got closer and even held it in my hands without it protesting beyond a few nips with its pointy mouth, almost as if it didn't know to be afraid of me. The other lay motionless, apparently dead.
I took a closer look over the pink fluffy one, lifting up its flat arm, looking at how it was shaped. It seemed good for meat, so I killed it, cooked it, and ate it. I pieced together the bones and noticed some tiny little bumps at the ends of the arm, almost like little fingers that hadn't fully grown. The bone seemed normal enough, though hollow. The meat tasted good, but not terribly exotic.
After that, I took the smooth red creature and examined it closely. It had an appearance similar to the pink creature, but only on a superficial level: It had a pair of eyes, but they were more like decoration, as if someone carved and painted them out of whatever this material was. There was even a straight line down the length of its body, like two halves joined together imperfectly. There were even strange geometric marks on its belly, lined up in a perfect circle. On its back was a strange white knobby protrusion. I gently pulled at it and ended up twisting it, hearing little clicks underneath the skin. When I let go, the creature sprang to life, flapping its arms a few times. I dropped it and watched as its flapping slowed to a halt. I picked it up again, turned the knob several more times and threw the creature forward. It flew through the air for a while before losing its strength and fell to the ground.
I retrieved the creature and gently cut open its belly with my knife. There was nothing familiar inside. No blood, no entrails, just strange, smooth objects made of the same material as the knob. There were some spiral-shaped pieces of a shiny material, and white wheels with little teeth that would lock together. I winded the knob and watched the wheels turn. The teeth at the end of one wheel would push another into turning. I also noticed the shiny spirals get pressed tighter when I turned the knob and loosen as the wheels turned and the creature flapped. I even pulled out some of these parts and found that the creature could flap its arms once they were put back. It was the strangest experience I ever had.
I thought about these strange creatures for a while and came to some conclusions:
The pink fluffy creature was most likely a natural animal. It had a mouth, real eyes, bones, flesh, and all the internal organs of other animals. All of these parts were made of materials other animals already grow in their bodies. It probably came into being like other animals, when its parents mated, made a home, and raised it. It most likely needed to fly, to eat, to drink, and to find a mate to keep making more of its kind. It also probably needed to think about how to do all of those things and instincts to drive it towards survival and producing young.
The red smooth creature was a toy made to look like an animal similar to the pink one. It had no legs, apparently no mind, no internal organs except those needed to make it fly. This simplicity of its design suggested it had a distinct purpose: To fly and look like a living animal when it did. Such a purpose implies a craftsman. Without a craftsman, a creature that can't eat can't produce a child. Even if it had a child, such a child would be unable to grow without an ability to take in food. Without a way to eat and make replacement material, if something damaged it, it had no apparent means of healing itself, save a person making an identical part and replacing it. The geometry of the parts was also suspiciously precise, with perfect circles, straight lines, and right angles. These things almost never showed up in nature, especially not at that level of precision. Nature and life are complex, messy processes, with all sorts of forces working against or with one another. Simplicity is a sign of design. Simplicity implies an understanding of the forces of nature and the ability to isolate or control them to form such unnatural shapes.
I gathered a few supplies and put them in my boat, rowing in the direction I guessed the animals came from. Eventually, I came across a forested island filled with many animals like the pink fluffy one, only with a dazzling variety of color combinations. I walked around, noticing some smaller varieties of these creatures would fly away when they saw me. Some larger ones, about the size of the pink fluffy one did not. Some even cawed, squawked, and otherwise looked to challenge my presence. I killed a few of those for lunch and dinner.
I found a nest of twigs made by two of these creatures will small, undeveloped babies begging for food. The parents were red and white, but the babies' think fluff was pink. In another nest with two pink parents, the babies were varied: Red, pink, and white. After some thought, it occurred to me that the babies inherited part of their color from either parent. A red and a white would only produce pink offspring, but two pinks could pass down a discrete "red" or the "white" part of themselves and produce any combination from the result. Children often looked like they had some parts of both parents, but this made the heredity for one factor more obvious. If someone were to try to breed only pink creatures, they could never eliminate the tendency for red or white to show up, since, if heredity was discrete like I suspected, you couldn't blend the red and white by mating alone.
Also noteworthy was a nest with a violet baby. I could only speculate at this point, but it seems reasonable to suspect something went wrong when the parent's color was copied into the baby, producing a new color that might just stand out a little more in their mating dances. Or repel the opposite sex. Or it could do nothing. Such changes, even if they are random could, with the right circumstances, provide an advantage. Little 'mistakes' now and then could do something better in an unexpected way. If the mistake ended up being a disadvantage, no long term harm would be done to the creatures, since the unfortunate creature would be more likely to die before passing on that disadvantage. Even if it did pass it on once or twice, the struggle for survival would still make it difficult for those offspring.
There were many other possibilities for how that baby was born with violet fluff, but for now, I moved on.
My thoughts turned towards the larger territorial variety. Until I arrived, they were the largest creatures on the island. It's possible that being alone on this island, there was no benefit to keeping an instinct for running away from much larger creatures. But if circumstances changed and my tribe moved over here for hunting, the fearless ones would likely die out. Those who retained the instinct to fear large creatures would be more likely to escape a hunt and live to produce children. Not long after such a move, nearly all of them would have the instinctive fear. For the smaller ones, that would be less of a change, since they already deal with creatures larger than themselves. In fact, they could come to dominate, since smaller, more nimble targets would be harder to catch.
I felt my conclusion about the pink fluffy creature was quite secure: I saw others similar to it finding mates, raising young, and otherwise engaged in the struggle to raise the next generation. They were just like other animals, even if they had some odd features. I still needed to find out more about the smooth red creature, though.
I traveled further in my boat, eventually seeing a sandbar with a large wooden box on it. I broke off a side and found a number of smaller boxes made with a stiff sort of hemp-like material. They were painted with pictures similar to the smooth red creature, though in five different colors. Inside each one was a copy of mine, aside from the color. I examined each closely and found the similarity among the members disturbing. The only difference between the creatures were signs of tool working: They all had a seam down their length, joined quite precisely, though not perfectly. There was almost no variety in color, all of them entrenched in the five base colors with the exact same highlights and contrasts.
This convinced me further that these smooth creatures were crafted by intelligent beings like myself. They were simple. They did one task very well and little else, suggesting they were created for that specific purpose and nothing else. They showed signs of the tools used to create them. Other people craft images of living beings, and if my people had the knowledge of this one's inner workings, would create similar moving contraptions for our children as toys.
In short, these artifacts were the opposite of living things. When an animal creates its young, there is no sign of a guiding intelligence shaping or planning the offspring, only the parents being together and letting nature take its course. For unintelligent life, the struggle to perform this act is, unfortunately, quite merciless. To survive and sire young, a living thing needs to perform countless tasks. Those creatures that can perform all those tasks produce more like them, while those who can't die off. There is no purpose or intent behind this, just a simple, logical truth. We, as intelligent beings, create purpose and use what we can to accomplish our goals. This ability exists primarily because it has the effect of making us able to devise and pass on new ways to survive and prosper. The feeling of empowerment that comes from creating art, culture, and seeking new forms of understanding is a side effect we can enjoy.
An artifact created for a specific purpose is not restricted by the demands of life: It can be created, used, and discarded. It only needs to perform its specific purpose. If another is needed, the craftsman can just make a new one. For this reason, a tool can afford to 'die.' It has no inherent need to survive or reproduce itself.
Anyway, pretty well moved off the story and into an author tract. I can afford to, since it's my blog.
Of course, a lot of Creationists are going to miss the major points and speak as if I intended this one thing to be the end-all argument. This is just specifically addressing Paley's watch, replacing it with a mechanical bird alongside a real one. The problem that should have been glaring Paley and friends in the face: It's not complexity that defines design. Simplicity is often a better guide.
Another huge problem is that a watch and a living thing are very, very different. We already know about natural processes that can make new living things: Reproduction. This is a feature that watches and other human creations lack. Watches do not assemble new watches. The parts of a watch do not have any sort of self-organizing affinity. The chemicals that make up living beings do, however.
If you change this, and simulate watches that can reproduce with variation and are made of parts that have affinities, it's much easy to produce an accurate watch using evolution and a natural selection criteria that favors accurate timekeeping.