Premise 1: Living things are too well designed to have originated by chance
Premise 2: Therefore, life must have been created by an intelligent creator
Conclusion: The creator is god.

Watchmaker Argument
If you found a watch lying on the ground would you think it occurred naturally or would you believe it was made by an intelligent designer?

This was the proposal posited by the English apologist William Paley in the 18th century.
Because a watch is complicated and well structured it must have had a designer then by extension if you look at the world, you see it is complex and well structured, it is safe to conclude it too had a designer.
You can assume that if a watch was made by a watchmaker then a world was made by a world-maker.

This, however, is a false analogy; let’s use the complexity premise. If you said, for example, that the watch was complex and made in 1922, could you also infer that because the world is complex so it too was made in 1922?

This analogy also suffers a false cause fallacy in that complexity can only be caused by a designer. We know a watch was made by a designer because we have countless examples of watches made by designers and have no examples of watches that came into being naturally.

If we accepted that the complexity of something meant there had to be a designer, then god, an infinitely complex being, using the same logic must have had a designer too. It doesn’t end there either; the designer of god would have to be more complex than its design then it too must have had a designer, and so on ad finitum.

If you found a watch on the ground with a bottle beside it, you wouldn’t assume the watch and the bottle were made by the same designer. The watch would have a designer and the bottle would have a different designer. Is it then logical to look at the natural world and assume everything was made by one designer? Wouldn’t plants have a plant-designer and stars have a star-designer?

Also, a watchmaker wouldn’t be able to conjure a watch out of nothing, he would make use of raw materials and rearrange them to make his watch, so too would a world-maker have to rearrange pre-existing parts to make the world, not conjure it out of nothing.
Even if the world had a designer it is a giant leap to ‘god done it’, all other possibilities would have to be eliminated. Could it have been created by an all-powerful alien race? Could it have been created by completely naturalistic means? God can only be posited as the only possible means once all other possibilities have been excluded.

If god gets the credit for creating this beautiful, complex world at whose feet do we lay faults within this design? What about birth defects like a cleft palate or conjoined Siamese twins?
This is the foundation for the Dysteleological Argument or the Argument from Poor Design, and goes as follows:

Dysteleological Argument
Premise 1: An omnipotent creator would create organisms with optimal design
Premise 2: Organisms often have features which are sub-optimal
Conclusion: Either the organisms were not created by an omnipotent creator or that creator was not omnipotent.

Imagine I came to install a cable from the street to your house and instead of laying the cable directly from the front wall to the front of the house, I zigzagged it across the front lawn up the driveway around the garage and swimming pool and all the way back to the front wall - you would think I was insane.

Yet, this is what happens with the laryngeal nerve.
The recurrent laryngeal nerve is a nerve that connects the larynx to the brain. In the case of humans this nerve need be no longer than 150mm or 6 inches, yet it descends from the brain loops around the heart ascending to the larynx, covering a distance of about a meter (40 inches).

In the case of a giraffe the laryngeal nerve makes a detour of about 5m as it travels all the way down the long neck, loops around the heart before ascending all the way back to the larynx. So, why does it make this unnecessary detour? The answer is evolution – not design.

In the case of a fish, one of our very distant ancestors, the nerve would pass naturally from the brain past the heart to the gills, but as bodies evolved and the heart separated in distance from the brain and breathing mechanism it snagged the nerve, dragging it along.

Poor Design examples
Then there are the errors that simply defy comprehension.
Both breathing and feeding happen through one hole in the head – the mouth. This gives rise to the opportunity of food becoming lodged in the windpipe, the trachea, causing a person to choke, often leading to death.
Would a better design not have been to place a blow-hole, similar to that of a whale, on top of the head through which breathing would occur – freeing up the mouth to eat?
And right there I designed a better food/air intake mechanism than god did!

The brain, the most sensitive of organs, the one that can least afford to be damaged is placed the furthest away from the ground when someone is standing. The act of tripping or stumbling causes the brain to travel the furthest distance of any organ of the body all the while gathering the greatest momentum. This increases the chance of injury to the brain when it does strike the floor. Wouldn't it have been a better design to place the brain lower down and offer it some form of cushioning, like in the buttocks?
And right there I designed a safer brain housing than god did!

Designing humans with just two arms seems a little short sighted.
How often haven't you needed to ask someone to help you fold a sheet or hold a large piece of material so that you could cut it simply because you just didn't have enough hands available to do the job?

So, why do we have two arms instead of the more sensible four?
The answer is simple - evolution, not creation. We evolved from ancestors who originally ran on four limbs before eventually walking erect, morphing the front legs into arms.
Wouldn't four arms have been a much better design? Now I understand why my mother so frequently said “I only have two hands”

And lastly, but by no means least, in my very short list of examples. As a man I can fully understand how any god that created man must have been a woman. There is no way a male god would create a man and put the testicles outside of the body and in possible harm's way, where they are susceptible to being struck by a cricket ball, a frisbee or a mischievous friend in school.
Wouldn't a better design have been to put them inside the body cavity where they are safe and secure for reproductive purposes?

If I, as a mere fallible mortal, can see the faults in the design of man, how much more so would an omnipotent creator of the universe have been able to foresee these issues and address them at the design stage?

Surely a flawed design would suggest an incompetent designer.