A design rationale is an explicit documentation of the reasons behind decisions made when designing a system or artifact. As initially developed by W.R. Kunz and Horst Rittel, design rationale seeks to provide argumentation-based structure to the political, collaborative process of addressing wicked problems.
Overview
A design rationale is the explicit listing of decisions made during a design process, and the reasons why those decisions were made. Its primary goal is to support designers by providing a means to record and communicate the argumentation and reasoning behind the design process. It should therefore include: the reasons behind a design decision, the justification for it, the other alternatives considered, the trade offs evaluated, and the argumentation that led to the decision.
Several science areas are involved in the study of design rationales, such as computer science cognitive science, artificial intelligence, and knowledge management. For supporting design rationale, various frameworks have been proposed, such as QOC, DRCS, IBIS, and DRL.
History
While argumentation formats can be traced back to Stephen Toulmin's work in the 1950s datums, claims, warrants, backings and rebuttals, the origin of design rationale can be traced back to W.R. Kunz and Horst Rittel's development of the Issue-Based Information System (IBIS) notation in 1970. Several variants on IBIS have since been proposed.
The first was Procedural Hierarchy of Issues (PHI), first described in Ray McCall's PhD Dissertation although not named at the time. IBIS was also modified, in this case to support Software Engineering, by Potts & Bruns. The Potts & Bruns approach was then extended by the Decision Representation Language (DRL). which itself was extended by RATSpeak. Questions Options and Criteria (QOC), also known as Design Space Analysis is an alternative representation for argumentation-based rationale, as are Win-Win and the Decision Recommendation and Intent Model (DRIM).
The first Rationale Management System (RMS) was PROTOCOL, which supported PHI, which was followed by other PHI-based systems MIKROPOLIS and PHIDIAS. The first system providing IBIS support was Hans Dehlinger's STIEC. Rittel developed a small system in 1983 (also not published) and the better known gIBIS (graphical IBIS) was developed in 1987.
Not all successful DR approaches involve structured argumentation. For example, Carroll and Rosson's Scenario-Claims Analysis approach captures rationale in scenarios that describe how the system is used and how well the system features support the user goals. Carroll and Rosson's approach to design rationale is intended to help designers of computer software and hardware identify underlying design tradeoffs and make inferences about the impact of potential design interventions.
Key concepts in design rationale
There are a number of ways to characterize DR approaches. Some key distinguishing features are how it is captured, how it is represented, and how it can be used.
Rationale capture
Rationale capture is the process of acquiring rationale information to a rationale management