Aristotle used tomorrow's sea battle to fight off total fatalism

Aristotle noticed a trap: if 'there will be a sea battle tomorrow' is already true or false today, then the battle's happening or not seems fixed in advance, making every future event necessary. His way out, in De Interpretatione, was to deny that statements about open future events are yet simply true or false — leaving room for real contingency, not just certainty we haven't discovered yet.

— Aristotle, De Interpretatione — Chapter 9, on future contingents