 A rather different objectivist challenge is that the position of the proponent of MMR is inconsistent. The relativist argument is that we should reject moral objectivism because there is little prospect of rationally resolving fundamental moral disagreements. However, it may be pointed out, the relativist should acknowledge that there is no more prospect of rationally resolving disagreements about MMR. By parity of reasoning, he or she should grant that there is no objective truth concerning MMR.