Bava Kamma 51: Two Owners?

The rabbis consider some of the limitations to the ten handbreadth requirement for liability when an animal falls into a pit and is injured or dies.  What if the pit is altered in some way?  What if there rare reasons that it is dug within a home?  What if an animal falls from higher up than the ground?  And so on.

A new Mishna teaches about a pit that is co-owned by two people.  If the pit is uncovered and the first owner just walks by and then the second owner passes by, neither of them covering the pit, the second owner is liable if a person falls into the pit.

The Gemara has difficulty with the notion of a pit having two owners.  The original verse (Exodus 21:33) refers to a man who opens or digs a pit, not two men who dig a pit.  How can liability be assigned to anyone but the person who digs the pit?  The rabbis consider different situations.  For example, if one man digs the pit and another man plasters and cements the pit.  Or if one man digs the pit but another man adds whichever characteristics create the fumes in the pit that cause the pit to be lethal for animals that fall into it.  Or if a pit is eight handbreadths deep but two handbreadths of water are added to it.  

Our daf ends with a discussion about designation and taking ownership or acquiring something through the action of using that thing.  If one person hands his bucket to another person, he might be stating through this action that he is finished constructing the pit.  By acquiring the bucket, the second person might be taking responsibility both for finishing the pit and for ownership of the bit.  The transfer of the bucket might represent a transfer of ownership - and thus liability.