John Stuart Mill 
Utilitarianism – The Philosophy of the Greatest Happiness Principle 
What Is Utilitarianism (General Remarks), Proof of the Greatest-happiness Principle, Ethical Principle of the Idea, Common Criticisms of Utilitarianism

In this classic of the Western philosophy John Stuart Mill tried to explain why utilitarianism is the best theory of ethics, and to defend it against a wide range of criticisms. Mill did that by presenting ‘the principle of utility’ or ‘the greatest-happiness principle’ and offering proofs for his theory. He argued various criticism argument by argument doing a great deal to popularize utilitarian ethic. His work is widely recognized today as ‘the most influential philosophical articulation of a liberal humanistic morality that was produced in the nineteenth century.’
Contents:
General Remarks
What Utilitarianism Is
Of the Ultimate Sanction of the Principle of Utility
Of What Sort of Proof the Principle of Utility Is Susceptible
Of the Connexion Between Justice and Utility