Synthesis is a common activity in engineering design. It is widely recognized to be important to the whole engineering design process in general, and to the early design stages in particular. In the past, however, there remains lack of a set of rigorous metrics to evaluate the effectiveness of performing design synthesis in conceptual design. Based on relevant studies of abductive reasoning in logic, this paper introduces a set of domain-independent design synthesis metric: clarity, feasibility, testability, simplicity, and analogy. For each metrics, the rationale of including it is explained, and a systemic evaluation procedure is prescribed. Individually, each metrics addresses a particular aspect of design synthesis in conceptual design. Collectively, the combined consideration of all metrics as a single vector helps the designer to identify the most promising synthesis outcome, the best design concept, which both satisfies upstream objectives and meets downstream constraints.
