Design by argumentation is a natural character of design process with social participation. Issue-Based Information System (IBIS) is an information representation system based on a structured database. It provides a hierarchically linked database structure to manage design information and facilitate design by argumentation. In this paper, we explore the enhancement of IBIS with FRS (Fuzzy Reasoning System) technology. The FRS adds computationally implemented dynamic links to the database of IBIS. Such dynamic links can represent logic relations and reasoning operations among related issues which allows further clarification of relations among issues in IBS. The enhanced system provides a general framework to manage design information and to assist design reasoning, which in turn will contribute to machine assisted design. The final goal is to formulate a system that can represent design knowledge and assist reasoning in design analysis. The system can help designers in clarifying and understanding design related issues, requirements and evaluating potential design alternatives. To demonstrate the system and its potential use, we reexamine a design experiment presented by Schon and represent the design knowledge and reasoning rules of the architects with our system, FRS-IBIS.