A variety of scenarios including the IPCC's Emissions Scenarios have been described toward achieving the sustainable society. Describing such scenarios is a hopeful approach for drawing future images of sustainable manufacturing. However, there exist difficulties in understanding these scenarios rationally since their logical structure is ambiguous. This prevents us from relying on these scenarios and describing new scenarios by using existing scenarios. In order to support understanding, analyzing, and describing scenarios, this paper proposes the concept of Sustainable Society Scenario Simulator (3S Simulator). As the first step, this paper proposes a method for describing scenarios structurally for a rational understanding of scenarios. This method expresses a scenario in four levels; i.e., Scenario, Expression, Word, and Data Levels. Particularly, this paper focuses on Scenario and Expression Levels and formulates the “base” of a scenario to clarify rationales that logically support its conclusions. The results of a case study involving World Energy Outlook 2004 showed that the proposed method successfully clarifies the logical structure of the scenario and identifies its base of the rationale. In this scenario, it was revealed that many of conclusions are derived beyond logicality since the scenario inevitably contains future predictions.
