How do I make judgment calls on uncertain liabilities in reserving?

You can set reserves now, and the routine cases no longer rattle you. What unsettles you are the judgment calls, the uncertain liabilities where the numbers only take you so far and then you must decide. That discomfort is not a weakness in your skill. It is honesty. Anyone who feels perfectly sure setting a reserve on true uncertainty is not paying attention. The goal in these calls is not certainty, which does not exist here, but a decision you could defend to a reasonable person looking back. You are not trying to be right in a way only the future can confirm. You are trying to be sound given what could be known at the time. Those are different standards, and the second one is actually within your reach. For your next uncertain call, write down the two or three assumptions your number rests on, and why you chose them. That short record does two things: it forces your reasoning into the open, and it gives you something solid to stand on later. Judgment gets steadier when you can see the thinking behind it.