John Stuart Mill (1806–1873), the most influential utilitarian of the nineteenth century, refined an ethical tradition inherited from Bentham by adding qualitative distinctions to its quantitative framework. In Utilitarianism, Mill holds that actions are right in proportion as they promote happiness — understood as pleasure and the absence of pain — for the greatest number. Yet he insists that intellectual and moral pleasures are superior in quality to bodily ones: it is better to be Socrates dissatisfied than a fool satisfied. In On Liberty, Mill articulates the Harm Principle, holding that the only justification for restricting individual liberty is to prevent harm to others, a defense of freedom of thought, speech, and action against both governmental overreach and the tyranny of the majority. His The Subjection of Women (1869) extends these commitments by arguing that the legal subordination of women is wrong and a barrier to human progress.
Friedrich Nietzsche (1844–1900) launched an even more radical assault on the moral and religious foundations of Western civilization. His announcement that "God is dead" diagnosed the collapse of the Christian God as the foundation of Western morality and meaning, leaving behind a crisis of values. In response, Nietzsche proposed the Übermensch, or Overman — an ideal of a person who creates their own values and meaning in a world without inherent purpose. Underlying this ideal is the Will to Power, Nietzsche's claim that the fundamental drive of all living beings is not survival but the expansion and expression of power and creative force. The thought experiment of eternal recurrence asks whether one could affirm one's life if forced to live it identically forever, becoming a test of genuine life-affirmation. Nietzsche's critique distinguishes master morality, valuing strength, pride, and nobility, from slave morality, valuing humility, pity, and resentment, which he saw embodied in Christianity. His philosophical novel Thus Spoke Zarathustra weaves these themes — the Übermensch, eternal recurrence, and the death of God — into a poetic teaching that has shaped modern thought.