The basic cause of the French Revolution was the fact that the common people of France were not given any sort of real voice in their own government. They were relatively oppressed and were very unhappy with that state of affairs. However, their unhappiness could not directly turn into a revolution. Instead, the revolution was only able to happen when the financial problems of the French government opened the door to rebellion.
By the late 1700s, the French government was badly in debt. It had lost a lot of money paying for the Seven Years’ War and also in helping the American colonies rebel against England. The problem was that the government, which was a monarchy, needed cooperation from the aristocrats before it could raise money through new taxes. The aristocracy wanted more power while the monarchy wanted to remain absolute. This led to an impasse.
Eventually, the impasse was broken in 1788 when the king agreed to call a meeting of the Estates General. The aristocrats and the monarchy felt that this would allow them to make some sort of a new deal to share power. The problem was that there was also the Third Estate, the common people. They had had very little power even though they made up the vast majority of the country’s population. The calling of the Estates General gave the Third Estate the opening they needed to push for major change. This eventually caused the revolution.
Thus, the French Revolution came about when government debts forced the monarchy into a situation where the common people could try to take power.