The causes of the French Revolution, the uprising which brought the regime of King Louis XVI to an end, were manifold. France in 1789 was one of the richest and most powerful nations in Europe; only in Great Britain and the Netherlands did the common people have more freedom and less chance of arbitrary punishment. Nevertheless, the ancien regime was brought down, partly by its own rigidity in the face of a changing world, partly by the ambitions of a rising bourgeoisie, allied with aggrieved peasants and wage-earners and with individuals of all classes who were influenced by the ideas of the Enlightenment. As the revolution proceeded and as power devolved from the monarchy to legislative bodies, the conflicting interests of these initially allied groups would become the source of conflict and bloodshed.
Absolutism and privilege
France in 1789 was, at least in theory, an absolute monarchy, an increasingly unpopular form of government at the time. In practice, the king’s ability to act on his theoretically absolute power was hemmed in by the (equally resented) power and prerogatives of the nobility and the clergy, the remnants of feudalism. Similarly, the peasants covetously eyed the relatively greater prerogatives of the townspeople.
The large and growing middle class and some of the nobility and of the working class had absorbed the ideology of equality and freedom of the individual, brought about by such philosophers as Voltaire, Denis Diderot, Turgot, and other theorists of the Enlightenment. The example of the American Revolution showed them that it was plausible that Enlightenment ideals about governmental organization might be put into practice. Some of the American revolutionaries, such as Benjamin Franklin, had stayed in Paris, where they were in frequent contact with the French intellectuals; furthermore, contact between the American revolutionaries and the French troops who had assisted them resulted in the spread of revolutionary ideals to the French. Many in France attacked the undemocratic nature of the government, pushed for freedom of speech, and challenged the Catholic Church and the prerogatives of the nobles.
There is controversy over exactly how deeply Enlightenment ideals penetrated the various classes, and over the degree to which these ideals were simply cover for bourgeois self-interest. For example, Karl Marx writing in the Neue Rheinische Zeitung shortly after the Revolutions of 1848 wrote that in both the English Revolution of 1648 and in the French Revolution “the bourgeoisie was the class that really headed the movement. The proletariat and the non-bourgeois strata of the middle class had either not yet evolved interests which were different from those of the bourgeoisie or they did not yet constitute independent classes or class divisions. Therefore, where they opposed the bourgeoisie, as they did in France in 1793 and 1794, [that is to say, during the Reign of Terror] they fought only for the attainment of the aims of the bourgeoisie, albeit in a non-bourgeois manner. The entire French terrorism was just a plebeian way of dealing with the enemies of the bourgeoisie: absolutism, feudalism and philistinism.”  (http://www.marxists.org/archive/marx/works/1848/12/15.htm)
Since 1614, the French monarchy had operated without resort to a legislature. Kings had managed their fiscal affairs by increasing the burden of the ancient and unequal system of taxes, by borrowing money, and sometimes by selling noble titles and other privileges; however, because noble titles exempted the holder from future taxes, the purchasers of titles were effectively buying an annuity.
This led to the long-running fiscal crisis of the French government. On the eve of the revolution, France was deeply indebted, so deeply as to be effectively bankrupt. Extravagant expenditures by Louis XIV on luxuries such as Versailles were compounded by heavy expenditures on the Seven Years War and the American War of Independence.
Britain too had a great debt from these conflicts, but Britain had a far more advanced fiscal structure to deal with it. There was no counterpart to the Bank of England in France in 1789 and there was also far less ready capital in France, as it was not nearly as much a trading nation as was Britain.
Edmund Burke, no friend of the revolution, was to write in 1790, “…the public, whether represented by a monarch or by a senate, can pledge nothing but the public estate; and it can have no public estate except in what it derives from a just and proportioned imposition upon the citizens at large.” Because of the successful defence by the nobles of their privileges, the king of France lacked the means to impose a “just and proportioned” tax. The desire to do so led directly to the decision in 1788 to call the Estates-General into session.
Unlike the trading nations, France could not rely almost solely on tariffs to generate income. While average tax rates were higher in Britain, the burden on the common people was greater in France. Taxation relied on a system of internal tariffs separating the regions of France, which prevented a unified market from developing in the country. Taxes such as the extremely unpopular gabelle were contracted out to private collectors (“tax farmers”) who were permitted to raise far more than the government requested. These systems led to an arbitrary and unequal collection of many of France’s consumption taxes. Further royal and seigneurial taxes were collected in the form of compulsory labor (the corvee).
Many public officials had to buy their positions from the king, as well as the right to keep this position hereditary; they of course tried to have these expenses repaid by making a profit out of their appointment. For instance, in a civil lawsuit, judges had to be paid some fees by the parties (the epices); this put justice out of reach of everybody but the wealthy classes.
The system also excluded the nobles and the clergy from having to pay taxes (with the exception of a modest quit rent). The tax burden was thus paid by the peasants, wage earners, and the professional and business classes. These groups were also cut off from most positions of power in the regime, causing unrest.
Attempts at reforms
During the regimes of Louis XV (reigned 1715-1774) and Louis XVI (reigned 1774-1792) several different ministers, most notably Turgot, unsuccessfully proposed to revise the French tax system to tax the nobles. Such measures encountered consistent resistance from the parlements (law courts). Members of these courts bought their positions from the king, as well as the right to transmit this position hereditarily (the so-called Paulette tax). Membership in such courts, or appointment to other similar public positions, often led to the elevation into the nobility (the so-called noblesse de robe – “gown nobility”, as opposed to the nobility of ancestral military origin, the noblesse d’epee). While these two categories of nobles were often at odds, they both sought to keep in place their privileges.
Because the need to raise taxes placed the king at odds with the nobles and the high bourgeoisie, he typically appointed as his finance ministers, (to use Francois Mignet’s term) “rising men”  (http://www.outfo.org/literature/pg/etext06/8hfrr10.txt), usually of non-noble origin. Turgot, Chretien de Malesherbes, and Jacques Necker successively attempted to revise the system of taxation and to make other reforms, such as Necker’s attempts to reduce the lavishness of the king’s court. Each failed in turn.
In contrast, Charles Alexandre de Calonne, appointed finance minister in 1783, restored lavish spending more reminiscent of the age of Louis XIV. By the time Calonne brought together an assembly of notables on February 22, 1787 to address the financial situation, France had reached a state of virtual bankruptcy: no one would lend the king funds sufficient to meet the expenses of government and court. According to Mignet, the loans amounted to “one thousand six hundred and forty-six millions… and… there was an annual deficit… of a hundred and forty millions [presumably of livres].”  (http://www.outfo.org/literature/pg/etext06/8hfrr10.txt) Calonne was succeeded by his chief critic Etienne Charles de Lomenie de Brienne, archbishop of Sens, but the fundamental situation was unchanged: the government had no credit. To try to address this, the assembly “sanctioned the establishment of provincial assemblies, a regulation of the corn trade, the abolition of corvees, and a new stamp tax; it broke up on the 25th of May, 1787.”  (http://www.outfo.org/literature/pg/etext06/8hfrr10.txt)
The nobility’s reaction
The subsequent struggle with the parlements in an unsuccessful attempt to enact these measures displayed the first overt signs of the disintegration of the ancien regime. In the ensuing struggle, Protestants regained their rights and Louis XVI promised an annual publication of the state of finances, and a convocation of the Estates-General within five years.
The parlements objected to this as “ministerial tyranny”. In response, several nobles including Louis Philippe II, Duke of Orleans suffered banishment, resulting in a further series of conflicting decrees by the king and the parlements. The conflict spilled out of the courts (and beyond the nobility) with disturbances in Dauphine, Brittany, Provence, Flanders, Languedoc, and Bearn.
Despite ancien regime France being, in theory, an absolute monarchy, it became clear that the royal government could not successfully effect the changes it desired without the consent of the nobility. The financial crisis had become a political crisis as well.
These problems were all compounded by a great scarcity of food in the 1780s. Different crop failures in the 1780s caused these shortages, which of course led to high prices for bread. Perhaps no cause more motivated the Paris mob that was the engine of the revolution more than the shortage of bread. The poor conditions in the countryside had forced rural residents to move into Paris, and the city was overcrowded and filled with the hungry and disaffected. The peasants suffered doubly from the economic and agricultural problems.