It is difficult to suggest that there was any one cause of the French Revolution. The purpose, however, was clear: overthrow of the monarchy. The gradual growth of a revolutionary movement was the result of multiple factors, with the financial crises stemming from French involvement in North American conflicts certainly contributing. It would be an injustice to the study of history, however, to conclude that a revolution years in the making was attributable primarily to those financial burdens, considerable though they were. Rather, an argument can be made that the ideals associated with the Age of Enlightenment were the principle causes of the revolution of 1788. Those ideals, including equality, liberty, constitutionalism, and other hallmarks of a liberal society stood in stark contrast to the reigning monarchy, personified by King Louis XVI and his spouse, Queen Antoinette, the latter historically synonymous with autocratic disregard for the welfare of one's subjects.
The ideals of the Age of Enlightenment, or Reason, were certainly not unique to France. They were, however, central to the revolutionary fervor that swept the salons and saloons of Paris and the rural farm lands of a peasantry no longer interested in feudalism. The financial burden that resulted from excessive expenditures on overseas commitments contributed mightily, but if one were to point to a single major factor or purpose in the French Revolution, the ideals of the era constituted the greatest contributor to the revolt that overthrew the monarchy.