 In reply, some ideal utilitarians contend they can agree in this case the promise ought to be kept by adding a value to Ross’s list and say (the act of) promise keeping is non-instrumentally valuable (or at least that promise breaking is evil). The most plausible form of this argument states Ross must accept promise keeping is valuable because he accepts knowledge and justice are valuable and there is no real difference between these values and the value of keeping promises or the disvalue of breaking promises (Shaver 2011, 130ff.).