Hm. Since everyone's basically saying the same thing on the subject thus far, and decent non-solipsistic philosophical/literary threads come up so very rarely, I'll take this on a tangent by pointing out that technically it's very hard to provide a rational basis for free will in the first place.
I mean, how, exactly, do you define it? Is something free because you can't see the restraints that made a particular action or result necessary? Can it merely be a set reaction to an action? Well, rocks aren't free, they fall down if you drop 'em, because of the unseen force of gravity. So right there, no materialist model of the mind if you wanna believe it- quite rigid parameters in anything controlled by physical laws, it has to be a direct result of specific causes.
So theorize a soul, some metaphysical entity, as the Greeks most certainly would have (as most people do today). Just because it's not regulated by any laws we know of does that make it free from causation? Don't you typically take your hand off a burner because it's hot, pick your favorite flavor of ice cream because you prefer it, choose a different one when you want to try and contest determinism? All of these are direct results of tangible causes- thoughts, preferences, instinctual reactions to outside forces. Under the circumstances, no other result is possible unless you add in another variable of causation (i.e. they're out of chocolate so you go for one of those nasty fruit ice creams, you're so massively stoned you don't notice the burning, you're stuck in a philsophical quandary and can't make a choice either way). The only actions entirely free, entirely independent of causation, would have to be completely random. And it's pretty plain that not only are we not random entities, there is no way we would want to be, such would more or less negate the existence of a person as we know it, and in fact there's little or nothing that can be considered random in our Universe at all.
So, free will as it is termed here is a logical fallacy. You're always going to react to the stimuli around you in an ultimately predictable fashion (whether anyone can actually predict it is another issue- it'd be a rare case where one would know all the variables involved), and since those causes have their own causes, and so on ad infinitum, one who knew all the facts of the matter could claim there was a fate of some sort- since every action has a specific reaction, if you go down the line you could predict anything perfectly accurately.
But then, that's not going to help you on your paper in the slightest.
Steak: What you want is probably a school of philosophy called "weak determinism", which says basically everything I just had above but adds that "free will" is instead defined as actions with at least some direct causes being internal to the mind- i.e. ignoring indirect causation and claiming that so long as you aren't physically forced into something by, say, a psychopath with a gun to your head, you have free will. Events are still 100% predictable if one knows all the factors in a given situation, but free will still exists after a fashion. Seems like rather a cop-out to me, but it's a popular out from the dilemma above and has the whole free will/fate thing resolved.