Intelligent design advocates make the case that the universe is finely tuned, so much so that if you changed some small feature, the gravitational constant, or the mass of the proton, then the universe would be different, and life could not have been formed. They conclude that the intelligent construction of the universe, so finely tuned, creates proof that the universe was created by an intelligent creator. In other words, the intelligent creation is the result of an intelligent creator. The universe is intelligently designed, so there must be an intelligent creator, or God.
Let's look at this arguement. The main thrust of the argument is that because the universe, with it's natural construction of atoms has resulted in an organized table of periodic elements, and one of them, carbon, is the foundation of life, this natural construction could not have occured if the resulting organization weren't put into place to begin with.
Let's talk about Baseball. In baseball, the home plate is 90 feet from first base. Batters have their entire careers built around getting to first base as soon as possible after they hit the ball.
Good batters will get there about 30% of the time. Bad batters will get there about 20% of the time. Most batters will fall in between those two percentages.
Now let's change the dimensions of the ball field. Now say that the distance is not 90 feet but 89 feet. That means that more players will get to first base. Averages my go up so the the best hitters are over 35% and the worst hitters are now batting over 25%. The statistics have changed and the players will have to adjust their game to the new dimensions.
Or suppose the length is not 90 feet but 91 feet. The opposite will occur. More players will be out. Batting averages will drop, so that the best hitters are now batting around 25%; the worst hitters are batting around 15%. Again the statistics change, and the players have to adjust to the new dimensions.
But in both cases the game of baseball is still recognized. The conditions change but the game is still there. So let's take this kind of argument and apply it to the universe.
About 13 to 15 billion years ago, the big bang occurred. And let's say that one of the results of the big bang was that certain rules, and physical laws and constants were created that made the universe the way that it is. Let's call the rules and conditions by a simple term: "C" which the constant for the speed of light.
We also know that element # 6 is carbon. And carbon is the foundation of life.
Now let's suppose that in Universe #2, there was a big bang as well. But this time the constant of the universe is 1.1C. It is just a little bit bigger than C is in our universe. One of the consequences is that there are 134 naturally occurring elements. Carbon is one of them, but in this universe, element #48, our "Cadmium" is responsible for life, not carbon. Again in this universe there was a naturally occuring structure built around how the atoms were arranged. Life was not pre-ordained to start with Carbon, but with a different element.
Universe #3 is like universe #2 and Universe #1. But in universe #3, the constant is .98C, smaller than universe #1. As a result there are only 58 naturally occuring elements, and element #18, "Argon" creates life. And again with this universe, the atoms arranged in such away that the properties of the periodic table result in a very different configuration for what constitutes matter.
In all three universes, we see that it is not necessary to invoke a special design, or even that the design in one is unique. This means that an intelligent design in which there is only one way to create life, doesn't have to be.