Marxism makes three essential assumptions. First, Marxists believe that classes are the dominant actors the political economy and ape the appropriate unit of analysis. Marxists identify two economically determined aggregations of individuals, or classes, as central: capital, or the owners of the means of production, and labor, or workers.
Second, Marxists assume that classes act in their material economic interests. Just as Liberals assume that individuals act rationally to maximize their utility, Marxists assume that each class acts to maximize the economic well-being of the class as a whole.