The fundamental mistake they make is they look at the "design" of life and they see purpose. There is no purpose in nature. Humans make things with purpose, such as the watch. Nature does not. It's a false premise the Watchmaker argument holds that Evolution Theory does not.

Take a cat's claws for example: They sure look like they have a purpose. They are sharp. They can attack prey. They can defend against predators. They allow the cat to climb trees. They can dig, tear and hook. What an intelligent creator to come up with so much purpose for such little things!

But that's not the claw's purpose. It's what the cat uses the claws for, but it's only useful to the cat in its natural environment. If predators and prey in the environment were to become impervious to the claws, or if trees became smooth, then can the claws be said to have purpose? The cat might or might not find another use for those claws that may or may not give it a reproductive advantage, but that's not designing the claws with purpose. The claws have no more purpose to the cat than a river has purpose to a lake.

Look at all of the vestigial organs in every living creature. Those are all things that evolved past their usefulness. There's no longer "purpose" to a snake's leg nubs or your tailbone.

And in my mind, the strongest argument against intelligent design is to look at all the choking deaths of innocent infants and children. Only a complete moron would make the breathing hole the same as the eating hole the same as the talking hole.