The three social classes (upper, middle, and lower) represent a pressure cooker. Each of the three classes has different goals and aspirations in the social pyramid. If there is friction among the classes, a fire may ignite under the pressure cooker. If this occurs, change comes in one of two ways. Change from the top of the pyramid results in a period of "evolution" toward the establishment of democracy or socialism. Change from the bottom results in a "revolution" toward the establishment of a new government. It is the middle and upper classes job to "keep the lid on". They are responsible for opening the safety valve in order to allow some of the steam to escape. An example is passing laws to eliminate grievances of the lower class. If this is done, a long period of evolutionary change will lead the state toward democracy or socialism. If they do not open the safety valve, the lid may be blown off and result in a revolution or class war. The flammable material under the pressure cooker consists of the grievances of the lower classes. The middle or upper classes ignite the material because they are the only ones that have the education necessary to carry out a program of revolution. The leaders lead revolutions to gain power for themselves. .
The French Revolution is a great example of the Pressure Cooker Theory of Revolution. In the socio-economic pyramid, there are three estates. The first estate is the clergy of the Catholic Church. The second estate is the nobility. The third estate was compromised of everyone who was not a clergyman or noble. There were three groups within the third estate. They were the bourgeoisie (middle class), proletariat (city workers), and peasants (farm workers). A movement known as the Enlightenment swept through Europe in the 18th Century. The ones who came up with the ideas of the Enlightenment were called Philosophes. Most of them were French and bourgeois.
