A moral obligation arises out of duty to another. The one who made the promise is not bound by contract or law or any other legal premise. There are two types of moral obligation
The first one that is based on natural right or lay man's term: common human decency.
The second based is made due to an action or consideration that was given to him previously.
In this case Nelson's action falls into the second category of moral obligation. He performed a kind act for Reggie and Nelson is now indebted to him.
