To appear in Heams et al. (eds.), Handbook of Evolutionary Biology (provis. Title), Springer.

Please do not quote without permission. This is not the final version

Premise 1: In a group of social beings, an individual possessing the capacity to act in an altruistic manner improves the life expectancy of all the members of society. This is the reason why this capacity can be selected for. Premise 2: Human beings have evolved inclinations to think in terms of mutual advantage and to act in an altruistic manner. These tendencies are inscribed into their biological nature. Conclusion: It is morally required that human beings develop and make use of their capacity to act in an altruistic manner.

As Hume had already noted a very long time ago (1991: vol. 3: 585-86), deducing moral conclusions from purely descriptive premises is an elementary logical error. To make the reasoning proposed above valid, we would need to add a supplementary premise that contained a normative element. In this case, we would have to add a premise saying that required29. altruism is morally The question we must now address concerns the real contribution of Hume’s point. Despite what one might think at first glance, his point only makes sense in the strict domain of logical reasoning; within this framework, all that it claims is that a term (in this case, the moral component) cannot appear in the conclusion if it does not figure in the premises of the argument. But one cannot conclude from the fact that no moral conclusion can be logically deduced from descriptive premises that there is no possible relation between the descriptive moral30. and the To claim that would be to accept a strict dichotomy between facts and values at the ontological level. Yet that thesis is not only highly subject to controversy, moreover it cannot rest in any way on a purely formal argument such as Hume’s; it is perfectly possible to accept Hume’s point without, however, defending a dichotomy between fact and value (see Putnam 2002). Taking this line, James Rachels (1990) has correctly commented that it is not necessary to claim that some facts logically imply a moral judgement in order to ground that moral judgement; rather, one must produce the best possible reasons for accepting the judgement. This demand is clearly weaker, but it remains significant. I will return to this point in the next section.

## 7. The futile search for the ultimate foundations of morality

It is tempting to imagine that the difficulty concerning the shift from the factual to the normative is a sufficient reason to categorise EE as irrelevant to our normative reflections. But such a conclusion only follows if one demands an ultimate foundation for our moral norms. Moreover, if we take a look at the moral philosophy literature, it is evident that no current moral system manages to escape the problem of ultimate justification. Some moral systems rest entirely on universal principles (such as the utilitarian principle or the Kantian categorical imperative), while others are based on a certain number of fundamental rights (e.g. human rights); yet others are based on fundamental moral values. But none of them is able to furnish an ultimate justification for their base elements on which the theoretical edifice is built. The difficulty is only exacerbated in the case of conflict between different rights or values advocated by one and the same system; the problem of ordering produces infinite theoretical complications (on this, see Appiah 2008: 73-82). In the final analysis, to maintain their position, philosophers often claim that the base elements they

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