The Existence of Time Travel Would Invalidate Free Will

A good response, I must say! For this debate, I was focusing more on time travel as a concept rather than as a scientific means. However, I will still take this into consideration in my arguments. First, let me offer some clarification. My R2 arguments were a bit bare-bone, but I did that on purpose, meaning for it to be the basic idea behind my propositions. I intend to offer a more complex argument here. By the law of the excluded middle, we can conclude that either the future is definite or indefinite. In order for free will to exist, the future must be indefinite, since if the future were definite, then everything would be predestined, thus negating free will. An indefinite future is a bit of an abstract idea. One way of conceptualizing it would be the multiverse theory, specifically speaking the theory that every universe and timeline that could exist does exist. For every possible decision that could be made, a world exists where it has been made. Free will could exist in such a world as decisions are not predestined. One could argue that this is really just an infinite amount of linear timelines, therefore not exactly free will. However, as I said, the multiverse is simply one way of envisioning an indefinite future. I'm just using it as an example for my argument. So, imagine you are in your time machine again, and you travel to the future. If you successfully do so, you close off opportunities and possible routes time could have taken. You might say that the decision to time travel is what caused you to end up in the timeline you do. However, unless you only travel an extremely small time, there are bound to be more decisions that would split into different timelines along the way that you traveled. Of course, as I have said earlier, the multiverse theory is not the only possible form of an indefinite future. I simply used it as an example for my illustration above. Now onto rebuttals. As per your discussion of how my concept of time travel would violate natural laws... This is where discussions of time travel get really confusing. What exactly happens the instant something travels? I didn't really say, as I was approaching time travel as a concept without any real scientific details. The very existence of time travel seems to disobey natural laws, such as the law of conservation of matter (as you pointed out). This very law seems to make time travel impossible. Therefore, I believe this can be passed off simply to allow for a reasonable discussion. What I was going for was an idea that objects disappear from the timeline when traveling. They spontaneously reappear at the desired time. Therefore, if a being was able to reappear in the future, and the future was indefinite, it would have to duplicate infinitely for every possible version of that future, which doesn't seem to be a sensible definition of time travel. "And lastly, why must we even assume that to see our future means that it is immutable.... Can it not be the case of the ghost of Christmas future, i.e., that it is just the trajectory based on current actions? ::shrugs shoulders::" The Ghost of Christmas Future was more of "This is what your future will be IF you continue like this." It was a warning. Looking into the future scientifically would show a certainty. I look forward to your response!