One of the central questions in metaethics is whether morality is a fundamentally subjective or fundamentally objective domain. Are we, when we are discussing moral claims or making moral judgments, engaging in an activity where there are standards of correctness that are independent of our own subjective beliefs, wishes and desires? In this thesis, I will attempt to answer this question using an argumentative strategy borrowed from G. E. Moore: his famous proof of an external world by the waving of his hands. While Moore s argument might seem simplistic, the philosophical strategy behind it is deeply interesting. Moore took a claim from within the domain that was being doubted, and used it in an argument against a metatheory about the domain. This what I will do in the case of the moral domain. I will take premises from within morality itself, and use them in arguments against the metaethical theory of subjectivism. The specific arguments that result will be very simple. The discussion of what the use of such arguments can show will be quite complex. In the end the strategy of employing Moorean arguments against subjectivism will result in two distinct reasons to reject the theory, one from the independent force of the arguments themselves, and one from what the possibility of formulating such arguments against subjectivism says about the theory. Together, these reasons give us a relatively strong reason to reject subjectivism, and to embrace objectivism about morality.