In social, physical and behavioral sciences there are two research paradigms that form the foundations of the research. Research paradigms are a very extensive topic and to deal with such topic you need to go in a comprehensive discussion about them. Here in this article, we will only define the two basic research paradigms, their uses, and their characteristics. A paradigm is the complete approach or methodology to find answers of the problems. The paradigm is a methodology, an approach not just a method. It should be noted here that a method is different from a methodology; method can be a series of steps needed to perform a task while methodology is a series of methods that govern
What is a paradigm?
We know the world and understand it from two different perspectives, these perspectives are called as the epistemologies of knowledge. In general, we call them the quantitative epistemology and the qualitative epistemology. Some laws of life can only be understood when you apply quantitative methodologies while other can only be understood or better understood if you apply the qualitative epistemology or approach. For example, what is gravity? this question can be understood using the quantitative approach while if you ask why people behave in a certain way in a certain situation can be better understood using the qualitative approach.
Types of research paradigms
There are basically two types of research paradigms that govern the universe: positivist and constructivist paradigms.
Positivist approach to research
The positivist approach in the research is also called as the systematic and the scientific approach. The positivist approach uses quantitative research techniques and analysis. In physical sciences and medicine the use of the positivist approach is very common. In social and behavioral sciences the use of the positivist approach is less common. Some researcher prefers to combine the qualitative approach with the quantitative approach in social sciences, in this way they improve the credibility of social science research. Bryman states that Up until the 1960s, the ‘scientific method’ was the predominant approach to social inquiry, with little attention given to qualitative approaches such as participant observation.  Until l1960, there was a belief that a research can only be conducted using positivist approach or using quantitative techniques. Several scholars in social sciences started to emphasize the importance of the qualitative approach then, and, as a result, qualitative approach to research emerged.
Constructivist approach to research
The proponents of the constructivist or naturalist approach believe that the answer to several of the social science questions can only be gained by using a qualitative approach. In social science and behavioral science the subjectivity of the researcher cannot be completely eliminated in the research. It should be noted that there is a great difference between subjectivity and bias. In a qualitative approach to research, subjectivity to some extent is allowed as it is a part of the qualitative approach to research. Biases are never allowed in research even if it is any kind of the research.
Pragmatic approach to research
In recent years, several researchers like Morgan argued that there should have to be a pragmatic approach to research in social sciences. This approach neither denies quantitative approach nor it eliminates qualitative approach, rather it says that both approaches can be geared together in research. The pragmatic approach to research gives rise to the mixed methods research and its popularity in the social and behavioral sciences. Morgan and other scientists have worked a great deal in this regard to develop the methodology for a pragmatic approach to research. They have been successful to a greater extent since pragmatism solved several social science problems in a better manner. There are still serious implications in paradigms lost and pragmatism gained as stated by Morgan in his Journal of Paradigms lost and pragmatism gained.
Similarities between the research paradigms
No matter which research paradigms you prefer to use in your research but one thing is common in every paradigm of the research. Whatever paradigm or approach you follow the research should be free of bias and subjectivity. The research process should have to be empirical and scientific in nature. The results should be highly reliable and they should reflect only the truth. As Kumar R. in his book Research Methodology states that no matter what paradigm the researcher works within, s/he should adhere to certain values regarding the control of bias, and the maintenance of objectivity in terms of both the research process itself and the results drawn. 
- Bryman, A. (2004). Quantity and Quality in Social Research, London: Routledge. First published in 1988.
- Kumar, R., Research Methodology: A Step-by-step Guide for Beginners, Sage pub, London, 2000, P-13