Why Intelligent Design?
From what we know about the way the universe works, humans appear to inhabit a cosmic environment with variables that are remarkably well-suited for life as we know it (above, the famous "pillars of creation" as seen by the Hubble Space Telescope).
For example, the value of the gravitational constant--an equation that defines the amount of attraction between objects with mass--is just right for creating planets orbiting sunlike stars with lifetimes long enough for life to evolve. That must mean, intelligent design proponents say, the universe was designed by a supernatural being with life in mind.
Evolutionists Argue ...
The idea of a single finely-tuned universe shows a limited imagination, Prothero said. "There're lots of ways you can imagine a universe that is not finely tuned for us, but might be tuned for something else."
For example, some physicists have theorized that our universe is just one of many possible universes in an unimaginably large "multiverse." It should be no surprise then that, even without a higher plan, humans live in the universe that is hospitable to them.
(Explore some of Darwin's inspirations for evolution
Image courtesy NASA