Final answer:
Karl Marx is the individual who argued that society was divided into two primary social classes, the bourgeoisie and the proletariat, leading to class struggle and hierarchical stratification.
Step-by-step explanation:
The individual who argued that there were two social classes, the bourgeoisie (owners of the means of production), and the proletariat (the workers), creating a hierarchical stratification system was Karl Marx. Marx believed that society was fundamentally divided between these two classes, leading to class struggles and societal conflict. The bourgeoisie profited from owning the production means and exploiting the labor of the proletariat, who sold their labor for wages. Marx's theories indicated that the proletariat's oppression by the bourgeoisie was the root cause of social and economic inequalities and predicted an eventual collapse of the capitalist system, leading to socialism.