SF is what paves the way for new ideas, exploring the physical and ethical and cultural implications of change, so we can be ready for the change when it arrives. Instead, they're tools I use to help create realistic events and environments, things which certainly drive the plot and characters but which can't substitute for them. I like that definition. The Church of Transcendent Evolution in Bloom is a nice illustration of the human need to impose a spiritual or mythological dimension on events or forces that are powerful, frightening and obscure. The idea of science as mythology is certainly pervasive in our culture, but it's dead wrong.
Science is a process, a means of testing ideas to see whether they match observed reality.
But if we turn that myth into a hypothesis, we can begin testing it, ruling out possible reactions one by one. We find that none of them work. So maybe now you get the myth that lead can't be turned to gold. So myths are what you have before science is applied. Some stories are relevant to a particular time or place, some are timeless and universal, and some aren't relevant at all.