free will is a figment of our imaginations, we're all secretly being controlled by the gray matter inside our heads, these decisions being based upon past experiences (as iglak I believe has already said)
why is this in general science?
I think that people thinking there's a point to their lives makes them feel better, to not want to kill themselves off and the such like (as, once again, iglak has stated,) and therefore keeps the human race going. Personally, I believe that life has no real purpose, and that we're all just here. I'm not sure whether or not I believe in a "God" yet, but if there is, maybe we're just here? something to amuse him/her/them/it/me?
anyone around here read "The Swords Trilogy"? In that book, there were Gods who found the races of the world to be merely an object of amusement. They would start conflict, evolution, etc. purely for something to see. Maybe that's us? we're a GREAT BIG video game!