The Design of Design Ch. 3 Summary

The rational model is only an ideal. It is how we thing the design process should work but it is not how it really works. Often the designer has a vague or incomplete desired goal. We also don't usually know the design tree, we make it as we go. Each branch of the tree will influence some other part of the tree. Each node in the tree is a complete design. They only way to tell what is good is to exhaustively go through each outcome from each node, which is not very cost effective. Weighing the trade offs and constraints at each part of the design tree changes the outcome of the design. Even though there are a lot of problems with the rational model, it is still widely used.