Philosophy
The sun has risen every day of your life. That's not proof it will tomorrow.
David Hume pointed out we have no logical guarantee the future will resemble the past — every argument for trusting induction, because it's worked before, is itself an inductive argument, so it can't prove its own reliability without circularity. Science runs on induction constantly, yet philosophers still haven't fully closed the gap Hume identified in 1739.