The primary purpose of research conducted in social sciences, in general, is to reach valid and reliable information about social facts and events. As a social science, sociology aims to deal with the form, internal dynamics, and interaction of social phenomena and events using the most scientifically appropriate methods. However, there are various debates about what research method should be followed to reach scientific data in social sciences and sociology. Another discussion in social sciences is about the concepts used in scientific research methods and techniques. So much so that the concepts of research method, research technique, and research design are frequently used interchangeably in the social science literature. Research method can be defined as the path followed to achieve the purpose of the research. In this context, what are the basic epistemological and ontological assumptions, features, and debates on which quantitative and qualitative research is based? On what philosophical basis do these two main approaches differ? What are the main points of discussion on differences? How do these discussions affect the research design and process? Why should the researcher be aware of these discussions when choosing a research model? I would like to write an essay that gives in-depth answers to these fundamental questions at the doctoral level.