The theorist who contended that as a society gets bigger and becomes more complex, the society becomes more integrated is Emile Durkheim. Durkheim was a French sociologist and is considered one of the founders of sociology as an academic discipline.
In his book "The Division of Labor in Society," Durkheim argued that as societies grow and become more complex, they become more integrated through the division of labor. He believed that the division of labor leads to interdependence among individuals, which in turn leads to greater social integration and solidarity. He also argued that this division of labor leads to the development of more specialized institutions, such as the economy, the legal system, and education, that play a crucial role in promoting social integration.
Overall, Durkheim's work has been highly influential in the field of sociology and has helped shape our understanding of the relationship between the size and complexity of a society and its degree of integration