In this paper I argue that the dominance of certain paradigms and theories on policies can have an influence on the value added by impact assessments. A link exists between paradigms and theories and policies and consequently the practices humans develop to tackle real world problems. I also argue that different types of thinking (contained in paradigms and theories) need to be integrated, at least at the scientific level, to enhance our understanding of social phenomena. This in turn can have (...) a positive influence on policy processes that follow impact assessment recommendations. I am not arguing for the adoption of theoretical positions by practitioners, Instead, I contend that if impact assessments are informed by a variety of paradigms and theories, the policy practitioner might have a better understanding of the issue and the moral choices he or she needs to make. I will highlight the connection between theory and policies with practical examples from the social impact assessment of the De Hoop Dam, which was constructed on the Steelpoort River. I also argue for an integration of different theories to give a deeper understanding of real world problems. (shrink)