People are very good are finding patterns that are not there. For example since the begining of time people have looked at the sky and seen bulls, swans, scorpions etc. Or clouds, it’s a random collection of water vapor, not an elephant.
What if someone you know gave you a jigsaw puzzle in a plastic baggie and told you where it came from but that they did not know what it was. You could take three random pieces out of the bag and then claim that the puzzle is clearly a Parisan street scene. Or you could rearrange the pieces and claim it’s a farm scene. This is the equivalent of accepting a (semi) plausible scenario that does not contradict any known facts. That by itself does not lock it in as other scenarios may be possible that you simple lack the imagination to think of.
Obviously you need more pieces to “make sense” of the scene but at some point as more pieces are added more possibilities will come to mind. This is where it is easy to err as once you’re convinced you know what the scene is you can search for other pieces still in the bag to match your theory. [U][B]Anyone that has had a lot of experience in solving puzzles this way will keep in mind how easy this error is to make[/B][/U]. As more pieces are fit together at some point the number of possibilities willl start become fewer rather then greater as the imagination beocmes constrained.
Another point is the clues supplied by the knowledge of were the puzzle came from. Say I know it was found in my Aunt’s closet and I know she purchased popular puzzles from the local department store. If I have an idea of when it was purchased and what puzzles were popular at the time it will help assign probabilities. This is where the people with expertise in the field come in, they can sometimes judge if the scenario is at all likely or not.
If someone’s guess is that the scene is heretics burning in hell that likely tells us more about that person then about the clues available. Anyone heard the joke about the ink blot test where the punch line is “Me? You’re the one with all the dirty pictures.”?
Point being if you think you “know” the answer when a puzzle is being solved it might be smart to lay low till more pieces come in or at minimum hedge your bets a bit to avoid looking not so sharp.