Social causes and. economic causes
the three estates
...and long term war.... see notes of french revolution in this app

There is significant disagreement among historians of the French Revolution as to its causes. Usually, they acknowledge the presence of several interlinked factors, but vary in the weight they attribute to each one. These factors include cultural change, normally associated with the Enlightenment; social change and financial and economic difficulties; and the political actions of the involved parties. For centuries, the French society was divided into three estates or orders.

The first estate, the highest class, consisted of clergy.
The second estate consisted of the nobility.
The third estate consisted of the commoners. It included businessman, merchants,court officials, lawyers, peasants, landless labourers and servants.
The first two estates together were 10% of the population. The third estate was 90%. All of the many types of taxes were paid by the third estate. The society was based on the old French maxim "The nobles fight; the clergy and the people pay".

Beyond these relatively established facts about the social conditions surrounding the French Revolution, there is significant dissent among historians. Marxist historians, such as Lefebvre and Soboul, see the social tensions described here as the main cause of the revolution, as the Estates-General allowed them to manifest into tangible political action; the bourgeoisie and the lower classes were grouped into the third estate, allowing them to jointly oppose the establishment. Others see the social issues as important, but less so than the Enlightenment or the financial crisis; François Furet is a prominent proponent of the former, Simon Schama of the latter.