It is true with a personality shaped enough a person can overcome pure internal stimuli, but read my first post and note that I said that a person isn't ruled by just enviromental and biological factors. The psyche also plays a part.
I also can't seem to convince you on my point that people are 100% predictable, but I can only assure you for now that it is true due to mathematics and science (I would say mostly chemistry, eh?).
Free will does exist. You can have one preference that you always follow every time, so that people would say that you no longer do anything else, and then you have no free will. But the free will is what allows us to break that chain.
whenever we try to do something of free will we get frikken busted for it! like when we try to have s.e.x behind the bushes at school... woops said that out loud >_>
How I answer this question depends on the scope and the arena. It will differ depending on whether I approach philosophically, morally, or neurobiologically.
How about this then: our mind convinces us that free will must exist and is important to us.
From the same assertion- be careful of how you define rationality and consciousness.
Look, the whole reason the world is as screwed up as it is is because God gave us all free will, and unfortunately people choose the wrong choice way too much. Plus, if we had to love God because he made us do so, it wouldn't be true love. The fact that we have the choice to accept ot reject Him is the only way to have true love for Him.
Free will exists in those who are strong enough to show it. Peer pressure is something that kills that. Like, if your in third grade and your bestest friend is getting bullied and you know its wrong. Then what? You can tell on the bully but then your gonna get harrased. So, some people might not do something they want to just to keep themselves safe.
Florgee, Choosing your movie doesn't require will. But if you were gonna chose a movie for your class and half the class liked a movie that you liked, but the other side of the class that was more popular liked a movie you DIDNT like. Then [if you didn't have will] would end up picking the movie the popular kids wanted. [Again, example]
So, It just depends. You can be a follower or a leader in life, I suppose.
We do have a free will, just not completely free. If it weren't for laws to hold people back we would have insane killers on the loose with no police force to stop them. rules are here for a purpose. But we do have freedom of speech we can say what we want to say :|(off topic: bacon!!! =D)