In order to strengthen the explanatory ability of urban planning and covering the gap between the theory and practice, various principles are got involved from other disciplines. Since 1960, social, cultural, political and human factors became more important and with the emergence of critical approach, concepts such as power entered into social discussions and consequently influenced the field of planning. In this direction, different approaches of power in space and planning were introduced. According to emphasis of this research on political economy approaches, explaining the role of political factors (power) in the re-definition of urban planning theory is the major object of this article. In this way, the descriptive-explanative analysis and inductive-hypothesis method were used. Results indicate that with the advent of critical approaches, explaining the factor of power (politics) in social fields, the impact of capitalism mechanism on urban planning became apparent and consequently urban planning was redefined
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