This lecture delves into the theory of utilitarianism, discussing how human agents act based on rules and the concept of treating others as ends in themselves. It explores the idea of co-legislators forming rules for living together and the importance of balancing individual will with the common good. The instructor also examines the interplay between different dimensions of well-being and the complex unity of the concept of 'the good'. The lecture concludes by emphasizing the need to consider all aspects of a person's life and talents in achieving a fulfilling existence.