This paper presents a novel argumentation framework to support Issue-Based Information System style debates on design alternatives, by providing an automatic quantitative evaluation of the positions put forward. It also identifies several formal properties of the proposed quantitative argumentation framework and compares it with existing non-numerical abstract argumentation formalisms. Finally, the paper describes the integration of the proposed approach within the design Visual Understanding Environment software tool along with three case studies in engineering design. The case studies show the potential for a competitive advantage of the proposed approach with respect to state-of-the-art engineering design methods.Keywords: argumentation; debate; design rationale; Issue-Based Information System (IBIS); decision support Engineering design is often described as an information-processing activity based on problem-solving within the constraints of bounded rationality (Simon, 1996;Simon & Newell, 1971). It consists of decomposing an initial problem into a range of sub-problems, proposing and assessing partial solutions, and integrating them as to satisfy the overall problem. This process is collaborative and often involves communication between non-co-located engineers. The development and communication of design solutions require engineers to form and share design rationale, that is, the argumentation in favour or against proposed designs.These aspects of the engineering design process have led to the development (Kunz & Rittel, 1970) and subsequent investigation (Buckingham Shum & Hammond, 1994;Fischer, Lemke, McCall, & Morch, 1991) of the issue-based information system (IBIS) method, a graph-based formalisation of the decisions made during a design process along with the reasons why they were made. The IBIS method envisions a decision-making process where problems (or issues) are given solutions (or answers) after a thorough debate involving technical, economical, life, environmental and safety considerations. It also provides means to actively develop, communicate and record the reasons (or arguments) in favour or against the options explored during the design process. Initially, IBIS was conceived purely as a conceptual information system and its first implementations were paper-based and totally operated by hand. However, over time several software tools supporting editing and visualisation of IBIS graphs have been developed, for example, Compendium, DRed and design Visual Understanding Environment (designVUE) (e.g. see Aurisicchio & Bracewell, 2013;Buckingham Shum et al., 2006). These IBIS-based tools,

The mental state in which an individual claims an object as theirs is called psychological ownership. Psychological ownership is associated with motives, routes, affordances, and outcomes directly linked to attachment. This research introduces psychological ownership in the context of designing object attachment and identifies affordance principles that help facilitate it. A framework presenting the motives for and routes to psychological ownership is proposed to provide a holistic understanding of object attachment. In the framework each route to psychological ownership, that is, control, intimate knowledge, and self-investment, has a corresponding class of affordances. Overall a total of 16 affordance principles are identified through contextual inquiry with 4 objects (a car, a mobile phone, a pair of shoes, and a park bench). Previous studies have identified various elements of this framework but have fallen short of clearly defining and relating the motives, routes, and affordances to psychological ownership identified here. These affordance principles are readily mapped to experience design models and provide a practical resource for designers.Together, the framework and the affordances inform design decisions and move towards a prescriptive design method for facilitating object attachment.

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Contamination poses a significant problem to the circular economy, which derives much of its value from maintaining pure material flows. The aim of this paper is to frame contaminated interaction among other forms of contamination and investigate its effects on the circular economy. The research is based on a review of the contamination literature and case studies. We differentiate between three types of contamination influencing circular material flows: technical, which deals with fitness for use; systemic, which deals with efficiency in processing; and interaction, which deals with user-object interaction and decision making.Our focus is on developing a foundational understanding of contaminated interaction and how it influences circular processes. Through multiple examples, contaminated interaction is shown to create three barriers to the circular economy: downcycling, disposal and hindered circulation. Among other proposals to address contaminated interaction, the research calls for the development of experientially transferrable design-products that can move between users and uses without negative consequences.