According to Karl Marx and Engels, the class struggle involves four stages of organization, namely common conditions, consciousness of awareness, organizing revolution. In modern industrial society the capitalists are a class for themselves that is they are aware of their common interest. The workers are a class in themselves. Though their living conditions are similar, they are not conscious of their common conditions or their common interests. When they develop class-consciousness, they will become a class for themselves. It takes time to develop this consciousness but it is an inevitable development according to Marx and Engels. For the workers are collected in factories and they become aware of their common interests and discuss their common problems. Moreover some members of the bourgeoisie who are aware of the inevitable course of history also join the workers- the proletariat. Thus they also become leaders assisting the workers to develop a sense of awareness and purpose. This is considered the second stage towards revolution when the proletariat develops class-consciousness. The third and final stage is of class solidarity and class-consciousness is reached when member realize that only by collective action can they overthrow the ruling class and when they take positive steps to do so.
Karl Marx believed that following aspects of capitalistic society would eventually lead to proletariat developing into class for itself. Firstly capitalistic society is by very nature unstable .It is based on contradictions and antagonisms that can only be resolved by its transformation. In particular the conflict of interest between the bourgeoisie and proletariat cannot be resolved within the framework of capitalistic economy. The basic conflict of interest involves the exploitation of workers by the capitalists. Marx believed that this contradiction would be highlighting the contraction between social production and individual ownership. As capitalism developed the workforce was increasingly concentrated in large factories where production was a social enterprise. Social production juxtaposed with individual ownership illuminates the exploitation of the proletariat. Social production also makes it easier for workers to organize themselves against the capitalists; it facilitates communication and encourages recognition of common circumstances and interest.