The picket fence There was a fence with spaces you could look through if you wanted to. An architect who saw this thing stood there one summer evening. Took out the spaces with great care and built a castle in the air. The fence was utterly dumbfounded, each post stood there with nothing round it. Christian Morgenstern, The Art of Looking Sideways www.andrew.cmu.edu spacearchitectureabsurdity
What's wrong with the rational model We Don’t Really Know the Goal When We Start We Usually Don’t Know the Decision Tree – We Discover It as We Go The Nodes Are Really Not Design Decisions, but Tentative Complete Designs The Goodness Function Cannot be Evaluated Incrementally The Desiderata and Their Weightings Keep Changing The Constraints Keep Changing Frederick P. Brooks, Jr., What's Wrong With This Model? Changing constraintsDeciding what to designThe situation talks back