What is the fun in reading something about an author that is sure about everything?
What makes creative nonfiction writing interesting is the unknown and the working through of thoughts and ideas. The author is usually situated in some type of scene, whether it is past or present, and writing about that allows the author to reflect on this scene and make a new discovery about it. If the discovery has already been made, the unknown is diminished. This (self) discovery often comes in the form of self-critique, a cultural critique or a mild epiphany. By looking at the situation from different perspectives and analyzing it, we come to a conclusion, which is usually the theme of our writing.
Writing gives us a chance to explore and reflect on our own experiences, and part of the journey is turning that experience into some type of finding. If we go into the experience with our end goal already determined, we may lose some of that curiosity that makes it exciting.
Ambivalence is uncertainty, and in writing, that is okay. It is okay to be unsure of the theme of your writing; working through these uncertainties allows the reader and writer to understand the magic of writing- discovery. As we look at our experiences we come to realize something that was not there at first glance.
As writers we need to be less focused on the cut and dry truth of the matter, but more on the reflection of what got us there.