When I awoke I thought hazily about this quality of empathy that was missing from the people in the dream. Empathy is something all humans - and perhaps many animals - share. We would try to help someone in danger without thinking, even if there were no direct gain. A psychopath, a person without empathy, has a mental disorder. Although psychopaths seem to make excellent business leaders, the idea of a world full of them is what makes zombie movies so scary.
The concept that people are connected is not a theory. It is not just a part of our humanity, it is our humanity. If you are not sure, imagine a world without empathy.