You're sitting at a cafe in one of two armchairs; a coffee table separates you and the stranger in the adjoining seat. A few minutes pass and the stranger leaves, forgetting to take his empty cup from the table.
After some time, another stranger sits down. He's holding several books and a hot cup of coffee. The empty cup on the table is in his way, but with no knowledge of who the cup belongs to, he doesn't want to touch it; he probably assumes it's yours.
Whose responsibility is the empty cup?
It's easy to ignore responsibility when we can pass it off to someone else (especially if that person isn't around), but if we can alleviate suffering or provide assistance -- no matter how little -- we automatically inherit the responsibility to do so.
(This applies even if the suffering is directed at the same person who failed to be responsible: if we see a wallet or purse left behind, we feel responsibile to provide assistance by turning it in.)
The motivation to act comes easily when we witness suffering firsthand: the innate human elements of empathy and compassion allow us to sense when we are, without doubt, responsible to act.
But when things are a little less clear -- when our lack of responsibility can go unnoticed -- it's easy to conclude that "it's not my problem" and move on. This can happen even if we are able to solve the problem or be part of the solution.
We ignore dirty dishes in the sink, trash on the sidewalk, and the shy person at the party. We convince ourselves that we deserve to suffer, that we're incapable of changing, or that we're just not lucky. We push aside thoughts of poverty in India, inequality in Africa, or starvation the world over because “it’s too big; someone else will fix it; it’s not my problem.”
Except it is our problem, because we can do something to change it.