Mill critiques both intuitive and inductive schools of ethics for failing to clearly define or reduce their moral precepts to a single, authoritative first principle of obligation.

The author refutes the claim that utilitarianism is impractical due to lack of time for calculation, arguing that humanity has used its entire history to learn the consequences of actions through experience.

Mill argues that because human nature is psychologically driven to desire happiness, it serves as the sole end of human action and the ultimate criterion for morality.

The author laments the lack of progress in philosophy regarding the 'summum bonum,' noting that the foundation of morality remains a subject of intense and unresolved debate despite centuries of inquiry.

The author defends utilitarianism by arguing that all moral systems require secondary principles derived from human experience, and that the theory should not be blamed for the inherent complexities of human nature.