In the free will debate, there is a distinction to be made between the metaphysical views of determinism and fatalism. Determinism is a view about the nature of causation, that every event was necessarily caused by some prior events evolving in accord with the laws of nature. This thesis has direct implications for human agency, in that, if we are determined to act based on the past, we could not have done otherwise. Fatalism states that the unfolding of all events happens necessarily, neutral on questions of causation. On fatalism, the world—at any point in time— could not have been otherwise.
Most philosophers probably reject fatalism, but, as far as I know, there isn’t a name for the position. So, from here on out, I will refer to the negation of fatalism as anti-fatalism. To accept anti-fatalism, one would just have to demonstrate a possible difference in the evolution of the universe. I will argue that the only way to refute fatalism would be to demonstrate that the universe had an absolute beginning that was indeterministic. If the eternal universe model, or any alternative model of the universe is correct, then the world is, was, and always will be, necessarily the way that things are.
We can imagine that the past could have been different. Someone other than Benjamin Franklin could have invented the bifocals, Hillary Clinton could have won the 2016 election, and I could have majored in neuroscience rather than philosophy. Nothing (logically) impossible when it comes to the past being different. However, when we ask whether these things are metaphysically possible, it is going to depend upon on whether fatalism is correct. If fatalism is true, then all of these imagined events would be metaphysically impossible (though, still logically possible). Determinists regularly claim that it is possible that the past could have been different, and in those hypothetical alternative worlds, that we could have done otherwise. What sense of possibility does the determinist have in mind: logical or metaphysical? If logical possibility, then the claim is uncontroversial. There are no contradictions involved in supposing Benjamin Franklin’s cousin could have invented the bifocals or that Hillary Clinton could have won the 2016 election. If metaphysical possibility, the truth of the claim is not as obvious.
For the sake of argument, suppose that both 1) determinism is true, and 2) it was metaphysically possible for Hillary Clinton to have won the 2016 election (HC). For HC to be true, there must be a metaphysically possible world where either the past (e.g. No Russians) and/or laws of nature were different. But how could we explain the possibility of a difference if our universe is deterministic? On determinism, the possibility of a different present requires the possibility of a different past. But any change in the past requires either a subsequent change in the past, ad infinitum. Given that changing the past seems hopeless, one might be tempted to go back to the Big Bang to posit a change in the laws of nature. If the initial conditions of the universe were different, then Hillary could have won. But notice that we wind up in the same exact position as before. How could we explain the possibility of a difference in the initial state, if the universe is deterministic?
To make room for alternative possibilities, one has to introduce some randomness or indeterminacy for the laws of nature or initial conditions of the universe.* Assuming that the laws of nature arose at the moment of the Big Bang, and that there was no such thing as a past that preceded the singularity, one could hold that you can have indeterminism at the very beginning but that everything else afterwards was determined. Here, we have a possible world where determinism is true, but fatalism is not. However, one must assume that the universe had an absolute beginning and that it could have been otherwise. In making these assumptions, one must also rule out two other theses. Namely, 1) that the universe is eternal, and 2) That the initial state of the universe was necessary (fatalism). Given that ruling out 2 is the very thesis is question, it would be question-begging for the anti-fatalist to assume it is false (without argument).
Thus, for both anti-fatalism and determinism to be true, the universe must have had a beginning. On an eternal universe model, there is no beginning or point in which indeterministic elements could enter, for this would falsify determinism.