Social sciences use geographical divisions in order to constitute the phenomena with which they are concerned. Thus, a theory considering these divisions as autonomous objects, and explaining how they come into being, might represent a crucial addition to, or even indeed one of the cornerstones of these sciences. The urban form theory deals precisely with such objects; but can it epistemologically justify its claim to play so fundamental a role? This question leads us to submit this theory to critical scrutiny. We refer to Kant's work in order to understand under what a priori conditions a place in the inhabitable space can be determined by a geographical position. The analysis of the transcendantal foundations of structural geographical objects shows that the urban form theory is remarkably consistent with the architectonic of the three Kantian Critiques and legitimizes its scientific claims.