The Edge Foundation asked this question of 163 scientists, innovators, and other thinkers.
I haven't read all of their answers, but as a writer of fiction I loved the one by a psychologist at U.C. Berkeley, Alison Gopnik. Titled "Imagination is Real," here is how it ends:
In fact, I think now that the two abilities - finding the truth about the world and creating new worlds-are two sides of the same coins. Theories, in science or childhood, don't just tell us what's true - they tell us what's possible, and they tell us how to get to those possibilities from where we are now. When children learn and when they pretend they use their knowledge of the world to create new possibilities. So do we whether we are doing science or writing novels. I don't think anymore that Science and Fiction are just both Good Things that complement each other. I think they are, quite literally, the same thing.I encourage you to click here to read the entire thing. And if you've changed your mind about something, post it in the comments. I'd love to hear your thoughts!