gringo: You are correct; if you and your opponent can't agree, you can continue to play it out. Of course, this should generally just clarify what you were disagreeing about, and usually won't change the outcome of the game. You could go on playing like this into impossible circumstances until the board is full of places you can't move, but it's considered bad form not to pass when the game can make no real progress or resign when it's obvious you're going to lose. The general idea is that you pass once you know there's nothing more you or your opponent can do to gain territory (or when you are so far ahead that the game should end now). Your opponent can still keep playing, but if you've calculated things out, it won't do any good.