Final answer:
Egoism is the concept that suggests the happiness of the self is of the greatest utility, focusing on individual self-interest as the basis of morality, contrasting with Utilitarianism, which prioritizes the greatest good for the greatest number of people.
Step-by-step explanation:
The idea that suggests the happiness of the self is of the greatest utility is Egoism. Egoism is the ethical stance that treats self-interest as the foundation of morality. Unlike Utilitarianism, which favors the greatest happiness for the greatest number of people, Egoism posits that an action is morally right if it maximizes the agent's own happiness and self-interest.
Utilitarianism offers a contrasting view, prioritizing the collective happiness over the individual's. Altruism, another concept mentioned, refers to selflessly acting to benefit others without regard for one's own interests, which is distinct from both Egoism and Utilitarianism. Consequentialism, a broader category that includes Utilitarianism, suggests that the moral value of an action is solely determined by its outcome or consequence.
Altruism is not the correct answer as it concerns selfless actions that benefit others, not oneself. Consequentialism does not inherently prioritize the self's happiness but looks at the results of actions in terms of overall happiness or outcomes.