Current approaches to qualitative reasoning are largely based on a fixed framework for modeling the physical world and concentrate on the reasoning methods that support qualitative reasoning. This paper argues that we need several levels of abstraction and different viewpoints on how to model the physical world, in order to create systems that reason about the physical world in a flexible way. We present a framework that integrates the three basic approaches to qualitative reasoning and show how this framework can be used as a basis for a flexible qualitative reasoning system.