Chapter 7 - Qualitative Physics: Past, Present, and Future

Abstract

Qualitative physics is concerned with representing and reasoning about the physical world. The goal of qualitative physics is to capture both the commonsense knowledge of the person on the street and the tacit knowledge underlying the quantitative knowledge used by engineers and scientists. The key to qualitative physics is to find ways to represent continuous properties of the world by discrete systems of symbols. One can always quantize something continuous, but not all quantizations are equally useful. One way to state the idea is the relevance principle: The distinctions made by a quantization must be relevant to the kind of reasoning performed. This chapter describes what qualitative physics is, why one should be doing it, and where it came from. It discusses some open problems in qualitative physics.