What are the main features strengths and weaknesses of Realist theory of International Relations?

One the greatest strengths of Classical Realism is that it recognizes the similarities between the domestic political sphere and the global political sphere. In both, community and a sense of common values are preconditions for stability. Thus, Classical Realism gives us insight as to why violence has decreased dramatically since the beginning of the 20th century. Classical Realists contend that the decreased violence is the result of identity shifts through liberal democracies' forceful integration of states into the liberal democratic "world community." In contrast to Liberalism, Classical Realism asserts that the deterring of conflict is not correlated to the material effects of economic integration. Instead, it has to do with the shared feeling of community within the liberal democratic states. Democracies and advocates of liberal economies tend to expand and sustain this community through exercising their power in the name of justice and differentiating themselves from outsiders.