I am confused about the usages of "duty" and "obligation"
It seems that I could write:
He failed in his duty to lead the team.
as standard English. Could I then write this also:
He failed in his obligation to lead the team.
Good question. I think "duty" usually implies a sort of moral imperative A duty is something that affects you inwardly. Although the team looked up to him as a leader, he failed in his duty to lead the team.
"Obligation" usually implies a legal or rule-based imperative. It is the result of some kind of external constraint. Although his contract stated that he was the team leader, he failed in his obligation to lead the team.