Concept design is the most critical step in product development. Support for concept generation is mainly intuitive. In this paper, we present amethod - SOS (subjective objective system) - that is simple yet powerful, for generating optimal concepts in diverse disciplines. The method rests on four mathematical metaphors: it is composed of an objective and subjective components, it allows varying degrees of precision in modeling, it works by decomposing a complex problem into smaller sub-problems, and it uses highly simplified evaluations. SOS also reminds aspects of QFD but is quite different from it. It not only structures the decision process but also outputs the optimal concept given the customer objectives, the company context, and the available constraints. This solution is obtained by linear programming that allows the method to handle very large problems and solve them in negligible time. SOS has been evolved and refined over years of practical experience and research. The present version has been used in numerous successful real projects. We illustrate the use of the method in a realistic project.