The paper focuses on the concept of technical rules (according to an Aristotelian interpretation, i.e. as propositions that express a necessity: if you want x, you must do y). The thesis argued is that this concept is helpful in coping with some of the problems of both teleological and deontological planning theories. In particular the concept is useful in emphasizing the role of technical knowledge in planning and in ‘solving the relationship’ between planning and politics in a way consistent with the characteristics of liberal and pluralist democracies.