Duty is the cognate of trust. Duty is how we devise the future. On the basis of duty we transact with each other around the creative invention of what has yet to come into being.
Duty is the ground on which covenantal partnership is erected. Duty governs action where information is scarce or where communication is foreclosed. One of the hallmarks of the otherness of the covenantal partner is that communication with them is difficult to nearly impossible but not entirely impossible. Communication with the covenantal partner is largely by surmise. That inclination to do on my own what I surmise on my own you need me to do because you are doing the same on your own is the essence of duty.
Duty governs action in relationships like covenants where the bond is largely spiritual, where the experience of the other is highly attentuated. Duty is action in relationship in the absence of relationship. Faith is the bond in such occluded relationships as trust is the bond in relationships where the communication channel is robust.
Faith is trust based on grace rather than on experience.