ABSTRACT
Uncertainty in design exists in more than one guise. Uncertainty about what the user might do with the product, what foolish moves might be demanded of the artifact, is one form. But uncertainty permeates the whole design process every step of the way. It is what gives life to that process, what makes engineering the challenge that it is. The paradox is that in process continually strive to banish uncertainty, to make it certain, to "freeze the design," as must if it is to be realized. No longer is "caveat emptor" a sufficient response to the challenge of design for safety. The technical literature customarily makes a distinction between uncertainty and risk, i.e., the former qualifies features of the design, imagined scenarios of use, that are recognized as possible but about which one has little if any information about their probabilities of occurrence.
