Although he was one of the major philosophers of the Scottish Enlightenment, Adam Smith (1723–1790) is today best known for his work in political economy, notably his An Inquiry Into the Nature and Causes of the Wealth of Nations (1776), usually abbreviated as The Wealth of Nations. Other writers had developed the laissez-faire theory that government should leave people alone in the economic marketplace, but Smith provided the most thorough and influential defense of this doctrine.