This talk is going to be literally chapter 20 of Barwise and Seligman's book on information flow. Here's what they say, and exactly this is what I'm gonna explain to you:
When we use representations to reason about some domain, the nature of the representation can greatly affect the form of the reasoning. The choice of a good representation system for the problem at hand can make the reasoning much easier. Conversely, the choice of a poor representation system can make the reasoning more difficult or even impossible. There have been many attempts made to explain the various properties of different kinds of representation systems. One common intuition is that the better a fit there is between the representing domain and the represented domain, the better the representational system is. Atsushi Shimojima has used the basic notion of classification and constraint to give a rigorous formulation of this basic intuition, and has used it to investigate a wide range of representational phenomena.