>>82836880
That's still circular, you're just defining moral truths as "things we're obligated to follow." The question is why they obligate anyone.
Your analogy to epistemic norms doesn't solve it, because even those depend on a goal we choose (being rational). if someone rejects that goal, the "ought" loses authority.

Facts can describe order, but they don't command obedience without a conscious source or purpose behind them.