From Explaining Society: Critical Realism in the Social Sciences, written by Berth Danermark:
As the social sciences deal with open systems, causal conditions in particular must be analysed as tendencies. Consequently the social sciences cannot make predictions in the proper sense of the word. Social science is often concerned with very complex matters, in the sense that a very large number of mechanisms are active. Time and again social science is criticized for not being able to explain what it does. Such criticism reveals a perspective which reduces the complexity of social reality. The view we argue for indicates that the task of social science first and foremost is to look for the causal mechanisms of the events we study. We cannot predict occurrences or anticipate situations; reality is too complex for that. But we can provide insight into the mechanisms and tendencies that make things happen in society. Today there are many social scientific theories drawing attention to social mechanisms; their explanatory power is huge even if they cannot predict concrete events.