The anthropic principle is a response to the seemingly coincidental characteristics of our universe that allow for life to exist. The anthropic principle states that if the universe were not able to support life, then humans would not exist to inquire about its ability to do so. Therefore, instead of understanding why the universe has formed in this way, we need to simply accept it as fact.
The second part of the anthropic principle states that because humans exist in our universe, and our universe is therefore able to support life, that the only possible universes that can exist are ones that support life. When pressed to elaborate on his anthropic principle, astronomer Brandon Carter explained that it was less about humanity, and more about the ability of a sentient life form to observe its universe. The fact that the life form is able to do so means that the universe is structured in such a way that the life form's existence is possible. For example, from Carter's perspective, questions that attempt to answer why or how the universe formed in just such a way to position Earth at the proper distance from the Sun, with the right elements to facilitate life, are senseless. In short, the universe formed this way, because it is this way.