Abstract: The techniques discussed herein generally relate to a method and system for qualitative modeling of and reasoning about the behavior of spatio-temporal physical systems. In some embodiments, qualitative representations based on Tonti diagrams are used to describe lumped or distributed parameter systems. Using a topological structure of the physical system, some embodiments generate qualitative governing equations as symbolic constraints on qualitative state variables. The qualitative constraints may be used to produce a qualitative simulation of the physical system. The qualitative simulation may be used to guide conceptual design iterations with given design criteria, or for instantiation of quantitative or hybrid (qualitative and quantitative) models and simulations.