One of the by-products of the Enlightenment was the invention of modern democracy. The critical second-guessing of received authorities and traditional wisdom also involved a critique of the God-given dynastic power of kings. Montesquieu's De l’esprit des lois not only outlined a legal-anthropological idea of the types of law and government that went with various societies in different climates and cultures; it also formulated, famously, the ideal of the trias politica or tripartite separation of powers (the requirement that power in the state should ideally remain in separate institutions, each independent of the other). Montesquieu was, of course, writing against the absolutist monarchy that reigned in France since the rise of Louis XIV; but his ideas have a far wider importance and bring a number of source traditions together into a highly influential and important form. Montesquieu's critique of the authoritarian state can be seen against a contemporary and against a classical background. One is his intellectual debt to Locke, the other his preoccupation with Tacitus.

John Locke (1632-1704) may count as one of the Enlightenment's great early protagonists. What is especially remarkable for our purpose is his characteristic combination of philosophical anthropology and constitutional thought. In his attempts to understand human understanding he pondered the growing mental capacity in the human individual, making him a precursor of Hume and one of the founders of modern psychology (Essay concerning Human Understanding, 1690); at the same time, he analysed political relations in two Treatises of Government (also 1690) – works which, published anonymously, were to prepare the democratic revolutions of 1776 and 1789 by way of the intermediary stages of Montesquieu and Rousseau.

The Treatises of Government were themselves written under the shadow of the parliamentarian coup d’état of 1688, when the English Parliament had foresworn king James II and in his stead had sponsored the rule of his daughter and his son-in-law, Mary and her husband William III. Much as this ‘Glorious Revolution’ had been foreshadowed by the Dutch Act of Abjuration of 1581, so too its political justification could fall back on political philosophers like Grotius, who argued that the relationship between king and people was essentially a contract.