The question about why we act morally, has been answered by philosophy as well as by psychology. Philosophy offers explanations that could be grouped in three types of positions: a) internalism or rationalism, derived from Kant; b) externalism or emotivism, derived from Hume; c) combination of positions. These positions are also present in psychology, although c) predominates. A critical analysis of the suppositions underlying the different positions, as well as the empirical evidence in morality and related fields of psychology, allows us to reject the first two positions in favor of the third
