One of the basic strategies to achieve a more accurate understanding of human sciences is to recognize the research philosophy in such sciences. The research philosophy enables us to identify the ontological, epistemological, and methodological foundations of each research method. Consequently, understanding these fundamental foundations leads us toward some areas of knowledge so that we can be more transparent in using appropriate research methods in different fields of science and knowledge. Considering the presence of the three dominant paradigms (namely positive, interpretive, and critical) in various fields of human sciences, this book is to evaluate the foundations of research philosophy in these three paradigms. In such an evaluation, not only the ontological and epistemological principles, but also the methodological principles regarding how to enter the experimental reality of the research are also introduced. The last chapter critically evaluates the philosophy of research in Islam and presents a proposed model in this regard.