In many scientific researches, whether quantitative or qualitative, the researcher seeks some basic assumptions about achieving a valid research. For this purpose, knowledge of these assumptions is essential to select the appropriate method in research, because the researcher's theoretical views play an important role in choosing the research method. In addition, factors such as the nature of the study environment, the research problem, the limitations of the research and the appropriateness between the subject matter and methodology are among the factors that are very decisive in determining...