The initial problem to be faced by naturalist investigations into morals is how to conceptualize it in a way that explains what ordinarily occurs in nature. In this sense, a vertical explication where actions are catalogued according to abstract theoretical constructions says little about the world. Therefore, the investigation presented in this article will be guided by an inverse methodology. It will refer to analysis of ordinary social behaviours which I will advance through the understanding of morality according to its (...) functionality. The concept of morals presented by Tugendhat, for whom morality is a combination of reciprocal demands expressed through sentences of duty based on sentiments, is of major importance to the way in which I will address the question. Moreover, I will carry out an accurate study of humean moral thought, with the objective of determining to what extent sentiment and reason influence the motivation to approve or censor socially relevant actions. Once we have investigated the natural aspects of the moral phenomenon, I will conclude the article presenting a possible compatibility between theoretical marks of humean empiricism and Darwin’s evolutionism. (shrink)