1800s: Martineau · Tocqueville · Marx · Spencer · Le Bon · Ward · Pareto · Tönnies · Veblen · Simmel · Durkheim · Addams · Mead · Weber · Du Bois · Mannheim · Elias Comparative sociology involves comparison of the social processes between nation states, or across different types of society (for example capitalist and socialist).
For example, structural Marxists have attempted to use comparative methods to discover the general processes that underlie apparently different social orderings in different societies.
The danger of this approach is that the different social contexts are overlooked in the search for supposed universal structures.
[1] One sociologist who employed comparative methods to understand variance was Max Weber, whose studies attempted to show how differences between cultures explained the different social orderings that had emerged (see for example The Protestant Ethic and the Spirit of Capitalism and Sociology of religion).
Emile Durkheim argued in The Rules of Sociological Method (1895) that all sociological research was in fact comparative since social phenomenon are always held to be typical, representative or unique, all of which imply some sort of comparison.