Moral disagreement is often thought to be of great metaethical significance for moral realists. I explore what remains of that significance when we look at moral disagreement through the lens of a combination of two influential and independently plausible hypotheses about moral language. The Morality-As-Cooperation (MAC) hypothesis says that our capacity for and use of moral language is an adaptation to increase mutualistic cooperation. The Concepts-As-Tools (CAT) hypothesis says that we often engage in disputes about language use and that many (...) apparent moral disagreements are linguistic disagreements in disguise. The combined MAC-CAT view that I explore suggests that we frequently engage in linguistic disputes to find optimal means for mutualistic cooperation. I show that this perspective weakens sceptical claims based on moral disagreements, that is offers a novel way for moral realists to explain the apparent genuineness of moral disagreements without the need to accept theses borrowed from non-cognitivism. (shrink)