 Even if it were established that there are deep and widespread moral disagreements that cannot be rationally resolved, and that these disagreements are more significant than whatever agreements there may be, it would not immediately follow that MMR is correct. Other nonobjectivist conclusions might be drawn. In particular, opponents of objectivism might argue for moral skepticism, that we cannot know moral truths, or for a view that moral judgments lack truth-value (understood to imply a rejection of relative truth-value). Hence, proponents of MMR face two very different groups of critics: assorted kinds of moral objectivists and various sorts of moral nonobjectivists. The defender of MMR needs to establish that MMR is superior to all these positions, and this would require a comparative assessment of their respective advantages and disadvantages. It is beyond the scope of this article to consider the alternative positions (see the entries on  moral cognitivism vs. non-cognitivism,  moral anti-realism,  moral epistemology,  moral realism, and  moral skepticism).  What can be considered are the challenges the proponent of MMR faces and what may be said in response to them. Some critics of MMR have raised questions about the coherence of the position (for example, Boghossian 2011 and 2017).