The rise of the Third Estate caused the French Revolution
Pre-Revolution France (Ancien Regime) was divided into three estates: The First Estate (The Clergy, people who worked in the Church), the Second Estate (The Nobility, or Aristocracy who included royals), and the Third estate (included lawyers, doctors, businessmen, merchants, soldiers, craftsmen, shopkeepers, peasants, and others). The Third Estate held the largest majority of the population. The First and Second estates did not pay any taxes, while the Third Estate paid all taxes to the King and the other estates. The First and Second Estates lived lavishly off of the extracted wealth of the Third Estate. When France began to have financial trouble, King Louis XVI called a general assembly of the three estates, known as the Estates-General. Even though the Third Estate represented 98 percent of the population, their vote was worth the same as the First and Second Estates. The outcome of the assembly was that the First and Second Estate wanted to keep their privileges. This infuriated the Third Estate, which is when they decided to break off and form the Assemblée Nationale, or National Assembly and planned to form a new constitution without the other estates' support. The forming of the new assembly overthrew the First and Second Estates. The Third Estate became what would be known as the first revolutionaries.
The over-taxation of the Third Estate did not cause the French Revolution as it is untrue. The Clergy and Nobility paid substantial sums of taxes, and taxes for the peasantry were lower than stated.