 One concept of rationality that supports the exclusion of sexual matters, at least at the basic level, from the norms of morality, is that for an action to count as irrational it must be an act that harms oneself without producing a compensating benefit for someone—perhaps oneself, perhaps someone else. Such an account of rationality might be called “hybrid”, since it gives different roles to self-interest and to altruism. An account of morality based on the hybrid concept of rationality could agree with Hobbes (1660) that morality is concerned with promoting people living together in peace and harmony, which includes obeying the rules prohibiting causing harm to others. Although moral prohibitions against actions that cause harm or significantly increase the risk of harm are not absolute, in order to avoid acting immorally, justification is always needed when violating these prohibitions. Kant (1797) seems to hold that it is never justified to violate some of these prohibitions, e.g., the prohibition against lying. This is largely a result of the fact that Kant’s (1785) concept of rationality is purely formal, in contrast with the hybrid concept of rationality described above.