A number of European monarchs also adopted certain of the ideas or at least the vocabulary of the Enlightenment. Voltaire and other philosophes, who relished the concept of a philosopher-king enlightening the people from above, eagerly welcomed the emergence of the so-called enlightened despots, of whom Frederick II of Prussia, Catherine II of Russia, and Joseph II of Austria were the most celebrated examples. The philosophes, in turn, were welcomed at their courts. Many ideas of the Enlightenment were useful to rulers, including educational and judicial reform, a trained bureaucracy, tolerance of (often talented and industrious) religious dissidents, and the abolition or improvement of serfdom, enabling peasants to pay more taxes. In retrospect, however, it appears that most of these monarchs used the movement in large part for propaganda purposes and were more despotic than enlightened.
The philosophes were united in support of tolerance, the rule of law, social welfare, and secular education, and in their hostility to privilege. They were not, however, opposed to the state as such: They viewed it as a crucial instrument for the realization of their ideals, as long as the ruler respected reason and natural law. Especially in central Europe and Italy, Enlightenment thinkers were more interested in strengthening the state so that it could do its job properly than in limiting its power. The main targets of their hatred were the church and the nobility.
The philosophes welcomed the American Revolution and the Declaration of Independence, seeing them as putting enlightened ideas into action. The Marquis de Condorcet, a moderate revolutionary who died in prison in 1794, argued in his Sketch of the Intellectual Progress of Mankind (1795) that the purpose of knowledge of human society can only be to guarantee the basic rights of men and, in his view, women. These rights are personal security, free enjoyment of property, equality before the law, and the participation of every citizen in government. The American states, he believed, were the first to convert these ideas into action.