The "Long Debate" on the nature of truth, the scale of real values, the life one should aspire to live, the character of justice, the sources of law, and the terms of civic and political life is encompassed by the name philosophy. Three persistent themes--understood as problems--are knowledge, conduct, and governance, on which there is a storehouse of insights, some so utterly persuasive as to have shaped thought itself. Beginning with Plato and Aristotle, the Stoics, Epicureans, and Scholastic philosophers, through the Renaissance to the Enlightenment and Romanticism to Darwin and Freud, these lectures examine the long history of the discipline in which humanity criticizes its own certainties and weighs the worthiness of its most secure beliefs.