The author proposes an investigation of contemporary moral naturalism based on the various formulations of the argument known as the naturalistic fallacy, as well as the counterpoint of some non-naturalistic theories such as those of G. E. Moore and John Rawls. Based on the analysis of these formulations of the argument in the formal context of contemporary metaethics, he seeks to assess the validity of the naturalistic fallacy in the current context, as well as its limits in its application against moral naturalism. Moral naturalism is then presented in a Humean version, which suggests a descriptive approach to morality, as opposed to a prescriptive bias. These origins, as well as some specific positions in metaethics, are analyzed in order to better understand the contemporary situation of the moral debate regarding the naturalization of ethics, contrasting theories of action and value on the theme of moral motivation and normativity.