“The history of all hitherto existing society,” wrote Marx in the opening of his 1848 Communist Manifesto, “is the history of class struggle.” In Marx and Engels's interpretation of history, civilized peoples live in a state of tension due to the competing socioeconomic interests between the differing classes. Aristocratic regimes fall to regimes based on property and ownership, which in turn fall based upon people fighting for the value of their own labor. This view that the class struggle provides the impetus for radical change is central to the work of both Marxists and anarchists such as Mikhail Bakunin.

As with everything, there are at least two ways to understand the term “class struggle” – each popular with competing theoretical groups. One approach understands it to mean a political movement where one or the other of contending groups considers itself to be a “class” (hence, having a class consciousness) consciously pursuing its interests. In the other, the class struggle inevitably breaks out wherever there is exploitation of one class by another. Thus, the worker who complains about unfair conditions and the boss who punishes him or her are both engaged in a class struggle, even if neither considers themselves to belong to a class. In the latter, the class struggle is a permanent, daily fixture in any industrial society.

This theory rose out of the idea that people follow their economic interests first and foremost. This, in the wake of the Industrial Revolution, put different classes of people on an inevitable collision course. In the 19th century, Marx saw a ruling class which owned the means of production – the land and its resources, the workshops and factories, the banks and schools. At the other end of the spectrum were the actual producers of wealth, those who own little but their ability to work hard for minimal wages. It was the inequities between the capitalist class and the working class that fueled the great ideological divide of the 20th Century and so shaped modern civilization.