Research traditions stem from people’s beliefs about truth and knowledge. Creswell (2003) identifies four research traditions that evolve from different knowledge claims: postpositivism, constructivism, advocacy, and pragmatism.
Postpositivism evolved from the older positivist view, which held strong beliefs about reality and truth being “out there in the world” waiting to be discovered through rigorous, objective testing. At the time when scientific research methods were emerging and people were learning more and more about the physical world, there was a great deal of confidence that the truth could be fully known and understood by careful, controlled observation. These positivist beliefs moderated over time, especially with respect to the social sciences, and led to an acknowledgment that human behavior does not follow laws equivalent to the laws of physics. (In fact, even our understanding of reality in the physical world has changed over the years.) Postpositivism, then, follows from the positivist tradition but in a moderated and, perhaps, more humble form. It retains the belief that there is objective truth in the world, and that if we make an effort to protect our research projects from our personal biases we can uncover a tentative approximation of truth, recognizing that our understanding will always be incomplete and imperfect.
Constructivism holds that reality, at least as it applies to the social sciences, is constructed by humans. That is, constructivists do not believe in an objective truth waiting to be discovered. Rather, meaning is constructed in human minds and through human interaction. This relatively more subjective view leads to very different beliefs about what we can know and understand. To understand the world, in the constructivist view, we need to seek understanding of human experience.
The advocacy (sometimes called critical) tradition is much more purposeful in its goals for research. While beliefs about reality and knowledge are probably similar to the constructivist tradition, those questions are not the focus of attention. The primary concern in this tradition is the power structures in society, which can oppress some groups of people. In the advocacy tradition the purpose of research is to find a way to facilitate change. The desired end goal is to emancipate people who are oppressed by a power structure, and to support them in implementing a desired change.
The pragmatic perspective focuses on practicality and expediency. Questions about truth and reality are almost “off the radar screen” in this tradition as researchers focus on the most effective way to answer a specific question in a given situation.