In addition to destabilizing social changes, the ideals of liberty and equality helped fuel revolutions in the Atlantic world. What did these concepts mean to eighteenth-century people, and why were they so radical and revolutionary in their day?

The call for liberty was first of all a call for individual human rights. Before the revolutionary period, even the most enlightened monarchs believed they needed to regulate what people wrote and believed. Opposing this long-standing practice, supporters of the cause of individual liberty (who became known as “liberals” in the early nineteenth century) demanded freedom to worship according to the dictates of their consciences, an end to censorship, and freedom from arbitrary laws and from judges who simply obeyed orders from the government.

The call for liberty was also a call for a new kind of government. Reformers believed that the people had sovereignty — that is, that the people alone had the authority to make laws limiting an individual’s freedom of action. In practice, this system of government meant choosing legislators who represented the people and were accountable to them. Monarchs might retain their thrones, but their rule should be constrained by the will of the people.

Equality was a more ambiguous idea. Eighteenth-century liberals argued that, in theory, all citizens should have identical rights and liberties and that the nobility had no right to special privileges based on birth. However, they accepted a number of distinctions. First, they generally believed that equality between men and women was neither practical nor desirable. Second, few questioned the inequality between blacks and whites.

Finally, liberals never believed that everyone should be equal economically. Great differences in fortune between rich and poor were perfectly acceptable. The essential point was that every free white male should have a legally equal chance at economic gain. However limited they appear to modern eyes, these demands for liberty and equality were revolutionary given that a privileged elite had long existed with little opposition.

The two most important Enlightenment references for late-eighteenth-century liberals were John Locke and the baron de Montesquieu (see Chapter 16). Locke maintained that England’s long political tradition rested on “the rights of Englishmen” and on representative government through Parliament. He argued that if a government oversteps its proper function of protecting the natural rights of life, liberty, and private property, it becomes a tyranny. Montesquieu was also inspired by English constitutional history and the Glorious Revolution, which placed sovereignty in Parliament (see "Constitutional Monarchy and Cabinet Government" in Chapter 15). He, too, believed that powerful “intermediary groups” offered the best defense of liberty against despotism.

Revolutions thus began with aspirations for equality and liberty among the social elite. Soon, however, dissenting voices emerged as some revolutionaries became frustrated with the limitations of liberal notions of equality and liberty and clamored for a more complete realization of these concepts. Depending on location, their demands included political rights for women and free people of color, the emancipation of slaves, and government regulations to reduce economic inequality. The age of revolution was thus marked by sharp conflicts over how far reform should go once it was initiated.