In the debate between determinists and compatibilists it is often repeated that the side arguing that free will and determinism are compatible are just playing word games, and changing the definition of "free will". However, it's probably the other way around. When the debate is first framed in philosophy 101 classes it causes people enter into a sort of confusion about what they had previously believed. It's hard to get at what people's pre-theoretical notions of freedom are, but we can certainly observe that no audience has ever gasped in shock like Marty does in this comic upon "learning" that people behave deterministically, and only by altering their environment would you alter their decisions. In fact, this is the basic premise of all time travel movies, and people find it so obvious that it never has to be explained. If the director wanted people to find it disconcerting that they supposed have no "free will", a large explanation would have to take place in order to get the audience to understand. Likewise, if the director wanted to depict the so call "libertarian" view of free will, that is that we are "truly" free and our souls or consciousness can make decisions outside of physics, the audience would also demand an explanation. I suspect that most people, upon learning that the mere act of going back in time and observing themselves again, might find themselves making different decisions for no apparent reason, would feel like they were less free. After all, if my decision to get married was based not on the kind of person I am, nor on the environment, but on something else entirely that can oscillate back and forth "freely", I might feel like the fact that I'm currently married wasn't so much my choice, but merely chance.

What concerns people about freedom in movies, it seems, is whether or not the action came from ourselves rather than a foreign object, not whether or not our decisions are somehow able to take place outside of the "laws of physics" (a strange idea to be sure, since the laws of physics merely describe what exists in reality, so whatever occurs in reality must be under them, i.e. it is definitionally true that nothing can break the laws of physics, because if they did we would just revise the laws to accomadate for this new information). While people do not react with horror that we make the same decisions every time, they probably would react with horror if a sci-fi movie shows that our decisions are secretly being made by a computer chip implanted in our brains without our knowledge. No one worries that the computer chip is deterministic, merely that it is not part of our being. The compatibilist account of free will, which seems to be taken for granted in time travel stories, is that freedom simply is having what we are be in control of our decisions.