  Taking the first tack, one might suggest that if the fact that one has promised is in some cases not a reason for doing what one promised to do, there will be some explanation of this. Suppose that the explanation is that what one promised to do was immoral. All one needs to do is to suck this feature into one’s account of the supposedly general reason. So now the reason in ordinary cases will be that one promised to do it and it is not immoral. We might object that not even this is always a reason. What if one’s promise has been extracted by duress? The response will be to suck that into the reason as well. This reason is growing all the time; now it is that one promised to do it, that it is not itself immoral, and one’s promise was not made under duress. This battle can continue; it has no obvious stopping point.  Still, we might say, eventually ingenuity will give out, and we will reach a (now very complex) specification of a reason to which we can think of no appropriate counter-example.