In evolutionary moral psychology–the field that wonders about the biological evoluation of our ability to moralize–there are three general positions. The first is that people have evolved specific moral rules, such as ‘don’t marry your kin,’ or ‘don’t kill members of your clan.’ A good number of scholars think this approach to be false. Sufficient anthropological research will show that the enormous amount of variety in moral systems makes it very hard for this to be correct. The remaining two positions are both plausible, in my mind.
The second position, supported by Marc Hauser in his book Moral Minds, is that people have evolved general moral rules. These moral schema give a framework for prohibited actions, such as ‘don’t harm a memeber of the in-group’, but leaves variable the notions of ‘harm’ and ‘in-group.’ Morality, according to this position, is innate. Hauser argues vigorously that the mechanisms of human development, such as the evolution of emotion and moral intuition, allows us to develop a system of morals within a quite limited range.
The third position is advocated principally by Jesse Prinz, a philosopher at UNC. Prinz believes that morality is in no way innate. In other words, it is not specifically evolved for. Instead, we tend to moralize certain things (read claim that something is moral or immoral) because of certain pragmatic reasons we have for succeeding in the world. Our ability to moralize is evolved but it is not specifically evolved for (this is what evolutionary theorists call a ‘spandrel.’ For another example, Duke philosopher Owen Flanagan thinks that dreams are spandrels.). We can moralize because of capabilities we have that were evolved for other reasons.
There are numerous arguments to be made in favor of Prinz and probably just as many in favor of Hauser. Without staking myself to one position or the other, I want to note briefly a point made implicitly by Hauser that I think is quite interesting. Were Prinz’s theory right, we could reasonably evolve any moral system that we like and have that be a coherent one. What determines a pragmatic reason is by no means restricted. Yet, as Hauser shows in his book, human moral systems, although varied, are quite similar and share a good number of both end-state characteristics (result) and developmental processes. This suggests, on first glance, that Hauser may be on to something. If our actual moral systems are similar, then there may be reason to think that there’s an evolved reason for this.