ABSTRACT
This chapter considers several other possible sources of human morality. It argues that theories that base human morality in reason, a human conscience, or a social contract are likely to provide elements of human morality but they are incomplete because they do not include moral content that arises more directly from the human psychological capacity for morality. This returns us to a more theoretical discussion of the topic of our last chapter, moral instincts. In arguing that the selfish gene theory is unlikely to explain the evolutionary development of such instincts, we continue our argument that the human psychological capacity for morality is likely to arise as a particular instance of a more general biological pattern of adaptation. This suggests that the natural kinds we argued for the existence of in earlier chapters are likely to be moral kinds.
