Suppose you are given some sort of puzzle and told that it is solvable, for example a game such as minesweeper adhering to certain rules. You've played it using logical decisions but have now come to a position where normally it would be impossible to proceed without guessing. However, when you use the fact that it has to be solvable, then you can eliminate one of the options because, were it that option, you would still have to guess somewhere, thus making the puzzle solvable.
I suspect the answer to this is no, and that using the fact that it is solvable would never let you proceed any further, but can someone give an explanation or even proof for it?