Who's Responsible?

In class yesterday we discussed responsibility and what our specific responsibilities are as rational autonomous agents in this world.  We got hung up on this point for a while because it is hard to view something as your responsibility unless you were an acting agent upon the situation.  This seemed fairly logical to me because I have mostly used the policy that if I wasn’t there then it was not my responsibility.  For example, if I was over at a friend’s house and my sister was home then it was obviously her responsibility to walk our dog.  This has always made sense to me and I have never really questioned otherwise until now.  This is due to Sartre’s idea of responsibility that one is responsible for everything in the world.  It is hard to fathom this idea that I have a responsible hand in everything that happens in the world, and in class at first we all struggled with this notion.  Personally, I think this might have been a result of a fear of having to be responsible for everything because then we would in a way feel at fault for all of the bad things that happen in the world.  Not to confuse fault with responsibility or anything, so maybe instead of fault we would in some way feel that we had more of a hand in everything and had some sort of influence.  I still am not sure how it is possible to have such a universal sense of responsibility, but maybe what Sartre is trying to get at can be explained through the example used in class about the Virginia Tech shooter.  I do not think Sartre is saying one is responsible for not seeing the signs of the shooter’s insanity and were not responsible enough to notice or report the behavior of the shooter.  But perhaps it is that we are a part of the community that in the end produced his actions.  All humans are interconnected and we all influence the world we are in.  So, maybe it’s this influence and the environment it has created that we are responsible for.  Thus, we created the community the shooter was in and we all had the influence on him directly or indirectly and therefore we are in a way responsible for his actions.  But keep in mind this new sense of responsibility is not only bad because if it is universal then we all also have a hand in all of the good things the happen in the world.