Excused by the unwillingness of others?

No one is excused from doing what he ought to do merely because he is unwilling to do it. But what if others are unwilling to play their necessary role in some joint venture that you all ought to undertake: might that excuse you from doing what you yourself ought to do as part of that? It would, if you were genuinely willing to play your necessary part if they were. But the unwillingness of everyone involved cannot reciprocally serve to excuse one another from doing what they ought to do