There is a deep-seated belief among planners that the historical association between urban planning and rationality is an unquestioned presumption which they follow their daily practices based on. It seems that truth of urban planning claims has been shown predominantly by applying the concept of rationality. As a result, reflection on rationality can be taken into consideration as an important subject for a study. This research may help us to find some answers for numerous questions such as below: What does it mean when planners claim that their practices are rational? Is there a grand unified theory of rationality determining the way of planning around the world which all of planners fit their daily practices with? This article makes a qualitative research to explain the two above questions, coming to this conclusion that planners should revise their belief about importance and universal concept of rationality within their practices.
