Marxism
Marxists believe that society is shaped by class conflict, and that society is divided into two social classes; the bourgeoisie and the proletariat. The bourgeoisie are the rich, capitalist minority who exploit the proletariat; the poor, working class majority who have to work for the bourgeoisie in order to survive.
The bourgeoisie own the means of production; eg) the land, factories and machinery, in order to make money. But the proletariat only have their own labour to sell, and so have no other means of survival than to allow themselves to be exploited by the bourgeoisie. The bourgeoisie want to extract maximum labour for minimum cost, so that they can ensure the profit margin is as high as possible.
Capitalism - the social structure in which the rich minority exploit the poor majority for economic gain - arose in the Industrial Revolution (1750-1900). Rich factory owners had complete control of the means of production, such as the factories themselves, the machinery inside them, and the economic capital to start a business in the first place. The working class simply cannot earn enough money working for the bourgeoisie to set up their own businesses. The proletariat are also alienated from each other and the products they are making.
The infrastructure (economic base of society) largely shapes the rest of society via the superstructure (social institutions which comprise society). Karl Marx (1818-1883) believed that the proletariat are controlled by ideology - powerful sets of ideas and beliefs that influence the way in which people think. Ruling-class ideology legitimates the bourgeoisie's position in society and reproduces inequality in the next generation, as the working class grow up believing that their social status is deserved and that they can earn a higher status with their own effort. In particular, the media, the family, the education system and religion are prominent institutions which transmit this ideology. Marx described religion as the 'opium of the people,' which eases the pain of exploitation in the capitalist regime. Most world religions advocate tolerance of suffering, and offer a promise of a reward in the afterlife if suffering is endured willingly, which Marx argues is a prime example of ruling class ideology, as it convinces the poor that their suffering is righteous.
Another crucial part of ruling class ideology is meritocracy, which is the belief that you can achieve a higher social status and economic reward with your own merit; talent and effort. This encourages the proletariat to believe that their place in society is deserved and their state of relative poverty is because of their own lack of talent and effort. It also increases faith in the capitalist structure of society, as people believe they can succeed in this way within it.
The mass media also helps to fuel capitalism with ideology. The media constantly advertises various goods and services, and encourages us to buy more and more material goods. We all want to be considered normal by having the latest products, which the ideology within the media makes us think we need. This then makes people believe they need a lot more money in order to have these products, so they are more inclined to work overtime for the bourgeoisie, ultimately producing more products and giving the bourgeoisie more profit.
Marx believed this would eventually lead to the overthrowing of the bourgeoisie, creating an equal, classless, communist society. The communist revolution is the only way in which society can be equal, as everyone will collectively own the means of production and share the profits of production fairly.