Chapter 9 revisits the logic of cooperation, arguing that intimate relatedness facilitates cooperation. Relatedness is a most significant explanatory variable for cooperation: the more intimately actors are related, the more likely they cooperate. There are three mechanisms: kin selection, Confucian improvement, and Mencius optimality. Kin selection reveals that family members tend to help one another even at the cost of self-interest, most explicitly showing how intimate relatedness promotes cooperation. Confucian improvement stresses the philosophy of "establish iff let established", somewhat resembling "direct reciprocity". Mencius optimality holds that a community of harmonious relations provides the best overall condition for its individual members to realize their self-interests. A serious obstacle to cooperation is kinsperson’s dilemma (KD), which occurs when one cooperates with a related actor, she has to defect from another equally related actor, even though she wants to cooperate with both. In world politics, therefore, how to manage relations constitutes a major problem and requires adept skills for decision-makers.