The thesis of this essay is that our experience of moral obligation makes sense most fully on the supposition that the moral law emanates from a transcendent source. The argument for the thesis goes as follows. The moral law has a cause. If the moral law has a cause, then that cause must be either natural or supernatural . If the cause of the moral law is natural, then it must be either biological instinct or man-made custom. If the cause (...) of the moral law is either biological instinct or man-made custom, then the moral law does not override instinct and custom. But the moral law does override instinct and custom. So, it is not the case that the cause of the moral law is natural. So, the cause of the moral law is supernatural. If the cause of the moral law is supernatural, then that cause must be some sort of morally good mind or person . So, the cause of the moral law must be some sort of morally good mind or person. (shrink)