Nicomachean Ethics

Lecture notes from Aristotle's time teaching at the Lyceum, arguing that the highest human good, eudaimonia, is achieved through virtuous activity in accordance with reason rather than through wealth, honor, or pleasure. Aristotle defines virtue as a mean between excess and deficiency, examines the special case of justice and friendship at length, and closes by arguing that a life of philosophical contemplation is the most complete form of happiness available to humans.

Aristotle opens by surveying and rejecting rival candidates for the highest good, pleasure, honor, and wealth, each pursued as an end in itself but each, on examination, too unstable or too dependent on others' opinion to serve as a final goal; eudaimonia, by contrast, is chosen for its own sake and is self-sufficient, the complete good at which all human action ultimately aims. His doctrine of the mean holds that each moral virtue lies as an intermediate state between two vices, one of excess and one of deficiency, courage between rashness and cowardice, generosity between wastefulness and stinginess, though the mean is relative to the individual and situation, not a mathematical midpoint fixed in advance, and some acts, like murder, admit of no virtuous mean at all.

Roughly a third of the work is devoted to friendship (philia), which Aristotle treats as essential to the good life itself, distinguishing friendships based on utility and pleasure, which dissolve once their basis disappears, from the rarer friendship between genuinely good people who wish each other well for the other's own sake. His treatment of justice examines both the general virtue of lawful conduct and the specific virtue governing distribution and correction, laying groundwork, particularly in his account of distributive justice as proportional rather than strictly equal, that later political and legal theory returned to repeatedly.

The work closes by ranking contemplative activity above the practical, active life of moral virtue as the most complete form of human flourishing, since it most resembles the self-sufficient activity of the divine, though Aristotle immediately qualifies this by acknowledging that a fully human life, embedded in a political community and dependent on external goods like health and friends, cannot dispense with the practical virtues either. Compiled and named after Aristotle's son Nicomachus, the treatise became the single most influential work of virtue ethics in Western philosophy, shaping medieval scholastic moral theology through Aquinas and enjoying a major revival in contemporary philosophy as an alternative to rule-based or consequence-based ethical theories.